US20190309399A1 - Stainless steel powder for producing duplex sintered stainless steel - Google Patents
Stainless steel powder for producing duplex sintered stainless steel Download PDFInfo
- Publication number
- US20190309399A1 US20190309399A1 US16/467,267 US201716467267A US2019309399A1 US 20190309399 A1 US20190309399 A1 US 20190309399A1 US 201716467267 A US201716467267 A US 201716467267A US 2019309399 A1 US2019309399 A1 US 2019309399A1
- Authority
- US
- United States
- Prior art keywords
- stainless steel
- powder
- sintered
- microns
- steel powder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000843 powder Substances 0.000 title claims abstract description 133
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 93
- 239000010935 stainless steel Substances 0.000 title claims abstract description 69
- 238000004519 manufacturing process Methods 0.000 claims abstract description 23
- 239000002245 particle Substances 0.000 claims description 35
- 239000000203 mixture Substances 0.000 claims description 33
- 229910001039 duplex stainless steel Inorganic materials 0.000 claims description 30
- 229910001566 austenite Inorganic materials 0.000 claims description 27
- 229910052757 nitrogen Inorganic materials 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 22
- 229910000859 α-Fe Inorganic materials 0.000 claims description 22
- 238000005245 sintering Methods 0.000 claims description 21
- 229910045601 alloy Inorganic materials 0.000 claims description 16
- 239000000956 alloy Substances 0.000 claims description 16
- 229910052804 chromium Inorganic materials 0.000 claims description 16
- 239000012535 impurity Substances 0.000 claims description 15
- 239000000126 substance Substances 0.000 claims description 14
- 229910052750 molybdenum Inorganic materials 0.000 claims description 12
- 238000005056 compaction Methods 0.000 claims description 11
- 229910052758 niobium Inorganic materials 0.000 claims description 10
- 229910052735 hafnium Inorganic materials 0.000 claims description 9
- 229910052759 nickel Inorganic materials 0.000 claims description 9
- 229910052719 titanium Inorganic materials 0.000 claims description 9
- 229910052796 boron Inorganic materials 0.000 claims description 8
- 150000004767 nitrides Chemical class 0.000 claims description 8
- 238000009692 water atomization Methods 0.000 claims description 8
- 239000000654 additive Substances 0.000 claims description 7
- 238000007596 consolidation process Methods 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 238000009689 gas atomisation Methods 0.000 claims description 5
- 239000000314 lubricant Substances 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 3
- 238000011084 recovery Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 24
- 239000012071 phase Substances 0.000 description 51
- 230000007797 corrosion Effects 0.000 description 38
- 238000005260 corrosion Methods 0.000 description 38
- 239000011651 chromium Substances 0.000 description 29
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 238000004663 powder metallurgy Methods 0.000 description 16
- 229910000831 Steel Inorganic materials 0.000 description 15
- 239000010949 copper Substances 0.000 description 15
- 239000010959 steel Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 239000011572 manganese Substances 0.000 description 10
- 230000002939 deleterious effect Effects 0.000 description 9
- 239000011159 matrix material Substances 0.000 description 9
- 239000010955 niobium Substances 0.000 description 9
- 229910052721 tungsten Inorganic materials 0.000 description 9
- 239000010936 titanium Substances 0.000 description 8
- TVZRAEYQIKYCPH-UHFFFAOYSA-N 3-(trimethylsilyl)propane-1-sulfonic acid Chemical compound C[Si](C)(C)CCCS(O)(=O)=O TVZRAEYQIKYCPH-UHFFFAOYSA-N 0.000 description 7
- 229910052802 copper Inorganic materials 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
- 238000003466 welding Methods 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- 238000000137 annealing Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000010791 quenching Methods 0.000 description 4
- 230000000171 quenching effect Effects 0.000 description 4
- 239000003381 stabilizer Substances 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- -1 e.g. Substances 0.000 description 3
- 238000001125 extrusion Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000001465 metallisation Methods 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000000149 argon plasma sintering Methods 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 238000001513 hot isostatic pressing Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000012805 post-processing Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910000593 SAF 2205 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 239000000112 cooling gas Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- YGANSGVIUGARFR-UHFFFAOYSA-N dipotassium dioxosilane oxo(oxoalumanyloxy)alumane oxygen(2-) Chemical compound [O--].[K+].[K+].O=[Si]=O.O=[Al]O[Al]=O YGANSGVIUGARFR-UHFFFAOYSA-N 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- HGPXWXLYXNVULB-UHFFFAOYSA-M lithium stearate Chemical compound [Li+].CCCCCCCCCCCCCCCCCC([O-])=O HGPXWXLYXNVULB-UHFFFAOYSA-M 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 229910052627 muscovite Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000011236 particulate material Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
- C22C33/0264—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5%
- C22C33/0271—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5% with only C, Mn, Si, P, S, As as alloying elements, e.g. carbon steel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
- C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
- C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
- B22F2009/0824—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with a specific atomising fluid
- B22F2009/0828—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with a specific atomising fluid with water
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/05—Light metals
- B22F2301/058—Magnesium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/10—Copper
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/15—Nickel or cobalt
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2304/00—Physical aspects of the powder
- B22F2304/10—Micron size particles, i.e. above 1 micrometer up to 500 micrometer
Definitions
- Embodiments of the present invention may provide a new stainless steel powder suitable for manufacturing of duplex sintered stainless steels.
- Embodiments of the present invention may also relate to a method for producing the stainless steel powder, the duplex sintered stainless steel as well as methods for producing the duplex sintered stainless steel.
- Duplex stainless steels have been known to the industry for more than 60 years. They are widely used in heat-treated cast, wrought and gas atomized powder forms, in many applications that require a combination of high strength and high corrosion resistance. However, they are unavailable today, in the water atomized powder form for use in press and sinter applications.
- duplex stainless steels Common uses for duplex stainless steels include chemical process plants pipeline, petrochemical industry, power plants and automobiles. They are also used in food processing industry, pharmaceutical process components, paper and pulp industry, in desalination plants and in the mining industry. Duplex stainless steels are known for their high resistance to inter granular corrosion (IGC) and stress corrosion cracking (SCC) in chloride media. Chloride is severe challenge that leads to rapid corrosion media for iron-based alloys.
- ITC inter granular corrosion
- SCC stress corrosion cracking
- austenite stabilizers e.g., nickel (Ni), manganese (Mn), carbon (C), nitrogen (N), copper (Cu) and cobalt (Co)
- ferrite stabilizers e.g., chromium (Cr), silicon (Si), molybdenum (Mo), tungsten (W), titanium (Ti) and niobium (Nb).
- duplex stainless steel As mentioned previously, the high strength and high corrosion resistance of duplex stainless steel is believed to come from a balance of ferrite and austenite in the microstructure.
- the microstructure depends not only on the chemistry but also on the heat treatment carried out on the material.
- All duplex steel compositions today make use of N in the chemistry, as N is a strong austenite stabilizer. N, when present in the alloy along with Cr, poses problem of forming nitrides which are deleterious to the properties such as strength and corrosion resistance.
- an intermetallic phase known as “Sigma” is formed in a heat affected zone (HAZ) due to slower cooling rates.
- HZ heat affected zone
- This Sigma phase is a hard, supersaturated, intermetallic phase containing Cr and Mo. The area around the Sigma phase is depleted of Cr and Mo and becomes weak and less resistant to corrosion. Often duplex stainless steels need annealing and quenching process to reduce or eliminate this Sigma phase.
- the steel In wrought or cast duplex stainless steels, the steel is solidified as ferritic steel and the austenite phase is precipitated out from ferrite during cooling of the alloy.
- the cooling rate is critical after casting or at any heat treatment, as the cooling rate determines the percentage of austenite and any intermetallic phases, precipitated within the structure.
- Typical composition of wrought duplex stainless steel is Fe with 21-23 wt % Cr, 4.5-6.5 wt % Ni, 2.5-3.5 wt % Mo, and 0.08-0.2 wt % N, such as for SAF 2205.
- the main obstacle in using low cost water atomized powders for conventional PM use is increased N and possibility of intermetallic and carbide precipitation due to cooling rate during the sintering.
- conventional sintering needs some wetting agents or low temperature melting constituents to increase free energy and accelerate the kinetics of austenite phase precipitation within ferritic matrix.
- SE538577C2 discloses a sintered duplex stainless steel made from gas atomized powder and having a chemical composition with a max 0.030 wt % C, 4.5-6.5 wt % Ni, 0.21-0.29 wt % N, 3.0-3.5 wt % Mo, 21-24 wt % Cr, and optionally one or more of 0-1.0 wt % Cu, 0-1.0 wt % W, 0-2.0 wt % Mn, 0-1.0 wt % Si wherein N is equal or greater than 0.01*wt % Cr and the remaining elements are Fe and unavoidable impurities.
- EP0167822A1 discloses a sintered stainless steel comprising a matrix phase and a dispersed phase and a process for manufacturing.
- the dispersed phase is an austenite metallurgical structure and is dispersed throughout the matrix phase, which is comprised of an austenitic metallurgical structure having a steel composition different from that of the dispersed phase or a ferritic-austenitic duplex stainless steel.
- JP5263199A discloses production of a sintered stainless steel comprising a matrix phase and a dispersing phase.
- the method includes mixing a ferritic stainless steel powder with a powder selected from an austenitic stainless steel powder, an austenitic-ferritic duplex stainless steel powder, an austenitic-martensitic duplex stainless steel powder and austenitic-ferritic-martensitic stainless triple phase stainless steel powder.
- the powder mixture being compacted and sintered.
- EP0534864B1 (Sumitomo) discloses a sintered stainless steel having a content of N of 0.10-0.35 wt % and made from gas atomized steel powder having the same chemical composition as the sintered stainless steel.
- N content helps the above properties, it can pose hurdles in post processing, such as heat treatment and welding operations, by forming chromium nitrides, which limits the use of duplex stainless steels in many applications.
- N increases the powder hardness making it less suitable for press and sinter applications.
- Embodiments of the invention overcome the problem with nitrides by avoiding the use of N in the chemistry, for example, having less than 0.10 wt % N or less than 0.07 wt % N, or less than 0.06 wt % N, or less than 0.05 wt % N, or less 0.04 wt % N, or less than 0.03 wt % N, and achieving phase balance and strength by alternative elements.
- Embodiments of the invention may enable production of water atomized powder with moderate compressibility for use in conventional press and sinter applications.
- Embodiments of this composition may also reduce precipitation of a deleterious ‘Sigma’ phase; irrespective of rate of cooling during sintering or annealing, mainly due to lower Mo content. Thus, minimizing post sintering heat treatments necessary to eliminate “Sigma” phase and minimizing sigma phase precipitation during welding.
- Embodiments of the composition may offer similar advantages when formed by gas atomization.
- compositions yield similar properties when processed with casting, direct metal deposition and additive manufacturing techniques.
- One object of certain embodiments of the invention is to provide an alloy powder for conventional PM that will produce a duplex structure during a sintering cycle.
- Another object of certain embodiments of the present invention is to provide a duplex sintered stainless steel.
- Another object of certain embodiments of the present invention is to obtain at least 35% higher tensile strength than ferritic steels such as 430L and double the corrosion resistance compared to austenitic steels such as 316L.
- Still another object of certain embodiments of the present invention is to provide a method for producing a duplex sintered stainless steel without the need of post sintering heat treatment.
- a stainless steel powder comprising, or consisting of, in weight percent:
- the unavoidable impurities do not include the listed elements of C, Si, Mn, Cr, Ni, Mo, W, N, Cu, P, S, B, Nb, Hf, Ti, or Co.
- Unavoidable impurities may include impurities that cannot be controlled, or controlled with difficulty, during manufacture of steels. These can come from the raw materials used and also from the process. These include, Al, O, Mg, Ca, Ta, V, Te, or Sn.
- the unavoidable impurities may be up to 0.8%, up to 0.6%, up to 0.3%.
- An unavoidable impurity may be O. O may be present up to 0.6%, up to 0.4%, or up to 0.3%.
- Another unavoidable impurity may be Sn present up to 0.2%, content of Sn above 0.2% is in this context not regarded as an unavoidable impurity and thus will be regarded as intentionally added.
- a stainless steel powder consisting of, in weight percent:
- the powder is ferritic.
- ferritic For example, 99.5% ferritic. Slight amounts of austenite, e.g., up to 0.5% may be tolerated.
- the powder is produced by water atomization.
- the powder is produced by gas atomization.
- the particle size of the powder is between 53 microns and 18 microns such that at least 80 wt % of the particles are less than 53 microns and at most 20 wt % of the particles are less than 18 microns.
- the particle size of the powder is between 26 microns and 5 microns such that at least 80 wt % of the particles are less than 26 microns and at most 20 wt % of the particles are less than 5 microns.
- the particle size of the powder is between 150 microns and 26 microns such that at least 80 wt % of the particles are less than 150 microns and at most 20 wt % of the particles are less than 26 microns.
- a sintered duplex stainless steel having a chemical composition according to the first aspect and embodiments thereof.
- Ni equivalent (Ni eq) is such that 5 ⁇ Ni eq ⁇ 11 and the Cr equivalent (Cr eq ) is such that 27 ⁇ Cr eq ⁇ 38.
- the pitting resistance equivalent number (PREN) is 28 ⁇ PREN ⁇ 33.
- the microstructure of the sintered duplex stainless steel is characterized by austenite phase precipitated within ferrite phase.
- the microstructure of the sintered duplex stainless steel contains 30-70% austenite and 30-70% ferrite. In embodiments of the third aspect, the microstructure of the sintered duplex stainless steel contains at least 99.5% austenite and ferrite, for example, at least 99.8% austenite and ferrite. The percentage of austenite and ferrite may be determined by ASTM E 562-11 and ASTM E 1245-03.
- the microstructure of the sintered duplex stainless steel is characterized by being free from sigma phases and nitrides, for example, having less than 1% of sigma phases and nitrides.
- Examples of an inert atmosphere include nitrogen, argon, and vacuum with argon backfill.
- An example of a reducing atmosphere is a hydrogen atmosphere, an atmosphere of a mixture of hydrogen and nitrogen, or an atmosphere of dissociated ammonia.
- a hydrogen atmosphere an atmosphere of a mixture of hydrogen and nitrogen, or an atmosphere of dissociated ammonia.
- carbon dioxide or carbon monoxide atmospheres may be used.
- said consolidation process includes one of: Metal Injection Molding (MIM), Hot Isostatic Pressing (HIP) or Additive Manufacturing techniques such as Binder Jetting.
- MIM Metal Injection Molding
- HIP Hot Isostatic Pressing
- Additive Manufacturing techniques such as Binder Jetting.
- Methods according to the fourth aspect may include one of Laser Powder Bed Fusion (L-PBF), Direct Metal Laser Sintering (DMLS) or Direct Metal Deposition (DMD).
- L-PBF Laser Powder Bed Fusion
- DMLS Direct Metal Laser Sintering
- DMD Direct Metal Deposition
- forced cooling or quenching is excluded from the cooling step.
- Cr is a major element in stainless steels which forms a Cr 2 O 3 layer on the surface which then prevents further oxygen passing the layer, therefore providing an increased corrosion resistance.
- Ni is another major element which affects the properties of stainless steel. Ni increases the strength and toughness of the steel and also when present with Cr, enhances the corrosion resistance. Mo and W both impart the strength and toughness when present along with Ni. Mo also enhances the corrosion resistance along with Cr and Ni.
- Si acts as deoxidizer preventing O combining in the steel during melting, Si is also a strong ferrite former.
- Cu is austenite stabilizer. Cu also increases the corrosion resistance of stainless steel. Especially in conventional PM, Cu helps sintering by promoting liquid phase sintering.
- Embodiments of the invention provide a powder suitable for producing sintered duplex stainless steel, as well as the sintered stainless steel.
- the powder and the sintered stainless steel having a low or neglectable content of N. This eliminates the problem of formation of deleterious nitrides during fabrication of the sintered stainless steel.
- the sintered stainless steel is preferably produced from a compacted and sintered water-atomized powder since the low N content makes it possible to produce water-atomized powder with reasonable compressibility.
- Mo is normally present in stainless steel as it strongly promotes the resistance to both uniform and localized corrosion. Mo strongly stabilizes ferritic microstructure. At the same time Mo is prone to precipitate Mo rich “Sigma” and “Chi” phases at ferrite-austenite grain boundary. These are deleterious phases and affect strength and corrosion resistance adversely. However, due to lower Mo content in embodiments of the powder of the present invention, the possibility of forming sigma phase at any cooling rate is reduced, eliminating or reducing the need for the post processing heat treatment of annealing. This also means that the sigma phase will not likely form during welding operation, which is a common fabrication process for duplex stainless steels.
- Ni promotes an austenitic microstructure and generally increases ductility and toughness. Ni has also a positive effect as it reduces the corrosion rate of stainless steels.
- Cu promotes an austenitic microstructure.
- the presence of Cu in the powder of the present invention facilitates the sintering process by enabling liquid phase sintering.
- W is expected to improve the resistance against pitting corrosion.
- Si increases strength and promotes a ferritic microstructure. It also increases oxidation resistance at high temperatures and in strongly oxidizing solutions at lower temperatures.
- B, Nb, Hf, Ti, Co may enhance the properties.
- B when added in small % may help in liquid phase sintering.
- excess B, if present, may form borides, which are deleterious to both mechanical, and corrosion properties.
- Nb and Hf when present may stabilize the microstructure by preferentially combining with carbon forming fine carbides freeing Cr for the corrosion resistance.
- Ti in stainless steels may increase the tensile strength and toughness.
- Co increases the high temperature mechanical properties.
- Elements such as C, Mn, S and P should be kept at a level as low as possible in the powder of embodiments of the present invention as they may have a negative effect to various extent on compressibility of the powder and/or mechanical and corrosion preventive properties of the sintered component.
- unavoidable impurities may be tolerated up to a content of 0.8% by weight of the powder according to the present invention.
- composition of the powder according to embodiments of the present invention is designed such that the produced powder will have fully (e.g., at least 99.5%) ferritic structure in the powder form and austenitic phase is precipitated out during sintering cycle. This will allow controlling the ratio of ferrite and austenite by adjusting the sintering parameters.
- Ni and Cr equivalents are calculated based on following empirical formulae:
- Ni eq Ni+0.5Mn+0.3Cu+25N+30C
- the composition is targeted such that 5 ⁇ Ni eq ⁇ 11 and 27 ⁇ Cr eq ⁇ 38. This places the alloy in at the border of Ferritic—Duplex region on Schaeffler Diagram. At this point the alloy is almost entirely ferritic (e.g., at least 99.5%). Elements like Mo, W and Si are supersaturated in the ferritic matrix.
- the powder of embodiments of the present invention may be produced by conventional powder manufacturing processes. Such processes may encompass melting of the raw materials followed by water or gas atomization, forming a so called prealloyed powder wherein all elements are homogeneously distributed within the iron matrix.
- prealloyed powder in contrast to a premixed powder, wherein two or more powders are mixed together, is that segregation is avoided. Such segregation may cause variation in mechanical properties, corrosion resistance etc.
- the powder of embodiments of the present invention may be compacted in a conventional uniaxial compaction equipment at a compaction pressure up to 900 MPa.
- Suitable particle size distribution of the stainless steel powder to be used at conventional uniaxial compaction is such that the particle size of the powder is between 53 microns and 18 microns such that at least 80 wt % of the particles are less than 53 microns and at most 20 wt % of the particles are less than 18 microns.
- the powder of embodiments of the present invention may be mixed with conventional lubricants, such as, but not limited to, Acrawax, Lithium Stearate, Intralube at a content up to 1 wt %.
- Other additives mixed in, up to 0.5 wt % may be machinability enhancing agents such as CaF 2 , muscovite, bentonite or MnS.
- MIM Metal Injection Molding
- HIP Hot Isostatic Pressing
- extrusion additive Manufacturing techniques
- Binder Jetting Laser Powder Bed Fusion
- DMLS Direct Metal Laser Sintering
- DMD Direct Metal Deposition
- suitable particle size distribution of the stainless steel powder to be used is such that the particle size of the powder is between 26 microns and 5 microns such that at least 80 wt % of the particles are less than 26 microns and at most 20 wt % of the particles are less than 5 microns.
- suitable particle size distribution of the stainless steel powder to be used is such that the particle size of the powder is between 150 microns and 26 microns such that at least 80 wt % of the particles are less than 150 microns and at most 20 wt % of the particles are less than 26 microns.
- the particle size distribution may be measured by a conventional sieving operation according to ISO 4497:1983 or by laser diffraction (Sympatec) according to ISO 13320:1999.
- the compacted or consolidated body is subjected to a sintering process at sufficiently high temperatures in the range of 1150° C. to 1450° C., preferably at sufficiently high temperatures in the range of 1275° C. to 1400° C. for a period of time of 5 minutes to 120 minutes.
- a sintering process at sufficiently high temperatures in the range of 1150° C. to 1450° C., preferably at sufficiently high temperatures in the range of 1275° C. to 1400° C.
- other period of sintering time such as 10 minutes to 90 minutes or 15 minutes to 60 minutes may be applied.
- the sintering atmosphere may be vacuum, inert or reducing such as a hydrogen atmosphere, an atmosphere of a mixture of hydrogen and nitrogen or dissociated ammonia.
- the supersaturated elements in ferrite matrix precipitate out as an austenitic phase. Austenite will start precipitating out at the grain boundaries, will grow with further sintering and will precipitate within the grain itself.
- the composition of embodiments of the present invention should not form sigma phases or other hard and deleterious phases, e.g., Chi phase and nitrides, during cooling from an elevated temperature, irrespective of the cooling rate.
- the amount of sigma phase or other hard and deleterious phases is less than 0.5%.
- Forced cooling or quenching is thus not necessary to apply.
- forced cooling means that the sintered parts are subjected to a cooling gas at a pressure above atmospheric pressure. Quenching means that the sintered parts are submerged into a liquid cooling media.
- a microstructure as shown in FIG. 1 will typically be formed containing ferrite and austenite. Presence of both phases is responsible for elevated mechanical and corrosion properties. No, or significantly limited amounts of, deleterious phases such as sigma and chi are formed during cooling which are normal for current known duplex stainless steels. As another consequence, this property will reduce or eliminate the formation of such phases during welding where the heat affected zone (HAZ) experience varying cooling rates. In another consequence, this composition will limit the precipitation of such phases during processes such as casting, extrusion, MIM, HIP and additive manufacturing. Embodiments of the invented alloy has shown mechanical and corrosion properties that are comparable to or exceeding the wrought and PM products manufactured with known duplex stainless steel alloys.
- certain advantages of embodiments of this invention may include fewer tendencies to precipitate deleterious sigma and chi phases that affect the mechanical and corrosion properties. This is particularly of interest in welding. Most of the duplex stainless steel components are welded after they are formed. Welding imparts different cooling rates in different parts of HAZ. These cooling rates tend to precipitate sigma and chi phases along with nitrides due to nitrogen present in the current known alloys. Absence of these phases may eliminate the post heat treatments, which normally involve annealing at temperatures above 1200° C. followed by rapid cooling. This will in most cases becomes difficult when parts are welded to a bigger structure, limiting use of duplex stainless steel.
- FIG. 1 shows the microstructure of invented sintered stainless steel, austenite and ferrite phases are present in equal proportions in as sintered condition, black spots are porosity.
- FIG. 2 discloses a comparison of ultimate tensile strength (UTS) and corrosion properties of the invented sintered stainless steel compared to 300 and 400 alloys, (SAE grades).
- FIG. 3 shows a comparison of mechanical properties of the invented sintered stainless steel at different sintering conditions
- a stainless steel powder having a particle size below 325 mesh, i.e. 95 wt % of the particles passed 45 ⁇ m sieve, was mixed with 0.75 wt % of Acrawax as a lubricant.
- the chemical analysis of the stainless steel powder was 0.01 wt % C, 1.52 wt % Si, 0.2 wt % Mn, 0.013 wt % P, 0.008 wt % S, 24.9 wt % Cr, 2.0 wt % Cu, 1.3 wt % Mo, 1.0 wt % W, 0.05 wt % N, balance Fe.
- the obtained powder mixture was pressed in a uniaxial press and compacted into transverse rapture strength (TRS) bars, according to ASTM B528-16 at a compaction pressure of 750 MPa.
- TRS transverse rapture strength
- the pressed TRS bars were then sintered in 100% hydrogen atmosphere at 1343° C. with ramp rate of 7° C./minute for 45 minutes. This was followed by furnace cooling at rate 5° C./minute.
- the samples were then mounted and polished for microstructure examination.
- the polished samples were then electro-etched with 33% NaOH at 3V for 15 sec. Electro-etch with NaOH reveals the ferrite phase as tan, austenite as white (unaffected) and sigma phases in dark orange at grain boundaries within ferrite matrix.
- the microstructure observed is as shown in FIG. 1 .
- the microstructure shows approximately 50/50 mixture of ferrite (tan) and austenite (white). There is no sign of any sigma phase (dark orange) in the microstructure.
- the chemical composition of the stainless steel powders are shown in table 1.
- Stainless steel melts having various chemical compositions were melted in an induction furnace, the molten metal was subjected to water stream to obtain steel powder.
- the obtained powders was then dried and screened to ⁇ 325 mesh.
- the screened powder was ⁇ 45 microns i.e. 95 wt % of the powder particles were less than 45 microns.
- the powders were then mixed with 0.75 wt % of the lubricant Acrawax.
- Table 2 shows that the stainless steel powders according to the present invention can be used for producing sintered duplex stainless steel having desired mechanical properties.
- An embodiment of the invented powder with composition as in Example 1 was also sintered at various temperatures and atmospheres below, to show the effect on mechanical properties. Such data is plotted in FIG. 3 .
- TRS bars as in Example 1 were produced along with bars for 316L and 434L as representatives from austenitic and ferritic grades.
- the samples were then tested for corrosion in 5% NaCl solution at room temperature per ASTM B895-16.
- the corrosion was compared by the hours takes for onset of corrosion on the samples.
- the comparative data is plotted in FIG. 2 along with the UTS and YS for these samples.
- the diameter of the bubbles in the FIG. 3 represents the number of hours taken for the start of the corrosion on the samples.
- the corrosion test for the invented powder was discontinued after 3700 hours as there was no sign of corrosion and it already exceeded 3 times that of 316L samples.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Powder Metallurgy (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
Abstract
Description
- Embodiments of the present invention may provide a new stainless steel powder suitable for manufacturing of duplex sintered stainless steels. Embodiments of the present invention may also relate to a method for producing the stainless steel powder, the duplex sintered stainless steel as well as methods for producing the duplex sintered stainless steel.
- Duplex stainless steels have been known to the industry for more than 60 years. They are widely used in heat-treated cast, wrought and gas atomized powder forms, in many applications that require a combination of high strength and high corrosion resistance. However, they are unavailable today, in the water atomized powder form for use in press and sinter applications.
- Common uses for duplex stainless steels include chemical process plants pipeline, petrochemical industry, power plants and automobiles. They are also used in food processing industry, pharmaceutical process components, paper and pulp industry, in desalination plants and in the mining industry. Duplex stainless steels are known for their high resistance to inter granular corrosion (IGC) and stress corrosion cracking (SCC) in chloride media. Chloride is severe challenge that leads to rapid corrosion media for iron-based alloys.
- High strength and high corrosion resisting properties in duplex stainless steel are believed to be acquired due to a presence of ferrite and austenite phases in equal amounts. Such structure is generally achieved by using a balance of austenite stabilizers, e.g., nickel (Ni), manganese (Mn), carbon (C), nitrogen (N), copper (Cu) and cobalt (Co), and ferrite stabilizers, e.g., chromium (Cr), silicon (Si), molybdenum (Mo), tungsten (W), titanium (Ti) and niobium (Nb).
- As mentioned previously, the high strength and high corrosion resistance of duplex stainless steel is believed to come from a balance of ferrite and austenite in the microstructure. The microstructure depends not only on the chemistry but also on the heat treatment carried out on the material. All duplex steel compositions today make use of N in the chemistry, as N is a strong austenite stabilizer. N, when present in the alloy along with Cr, poses problem of forming nitrides which are deleterious to the properties such as strength and corrosion resistance. Further, during welding duplex stainless steels, an intermetallic phase known as “Sigma” is formed in a heat affected zone (HAZ) due to slower cooling rates. This Sigma phase is a hard, supersaturated, intermetallic phase containing Cr and Mo. The area around the Sigma phase is depleted of Cr and Mo and becomes weak and less resistant to corrosion. Often duplex stainless steels need annealing and quenching process to reduce or eliminate this Sigma phase.
- In wrought or cast duplex stainless steels, the steel is solidified as ferritic steel and the austenite phase is precipitated out from ferrite during cooling of the alloy. The cooling rate is critical after casting or at any heat treatment, as the cooling rate determines the percentage of austenite and any intermetallic phases, precipitated within the structure.
- Although wrought duplex stainless steels, in particular ‘hot rolled’ duplex stainless steels, have been common in industrial use since 1930s, they were hardly used in the Powder Metallurgy (PM) industry. There are a few applications where gas atomized duplex stainless steel powders are used in hot isostatic pressed (HIP) condition. Powders produced by gas atomizing have spherical morphology. Such powders are less suitable for conventional press and sinter applications. Due to the spherical shape, they have insufficient green strength, which is required to handle green press and sinter parts. Irregular shaped powders, such as those produced with water atomization, have much higher green strength as the irregular shape of the powders tends to bind together the powder particles. Currently there is no water atomized stainless steel powder available for producing sintered duplex stainless steel components. The current chemical compositions used in gas atomized powders, and also in wrought steels, use N as a major alloying element to achieve austenite-ferrite balance and achieve required mechanical strength. Inclusion of N in the powder increases the hardness of the powder reducing the compressibility in conventional press and sinter applications. This may result in reduced green density and subsequently reduced sinter density.
- There have been several attempts to develop sintered duplex stainless steels made from water atomized powders. Lawley et al1 attempted to develop equivalent grades of AISI 329 and AISI 2205 with maximum tensile strength of 578 MPa. Dobrzanski et al2 mixed ferritic and austenitic powders to produce duplex structure with tensile strength 650 MPa. The same group also studied the corrosion properties of duplex stainless steel with electrochemical method and concluded that the duplex stainless steels show better corrosion resistance than their austenitic counterpart3. Due to their high alloy content, these steels are sensitive to the composition and also the processing parameters. These alloys form intermetallic phases known as sigma, chi and gamma prime which are rich in Mo, W, N, Ni and Cr and reduce both mechanical properties and corrosion properties. Sigma phase forms in a temperature range 700° C. to 1000° C. whereas Chi phase forms within
range 300° C. to 450° C. The Gamma (austenite) phase may start forming at around 600° C. 1A. Lawley, E. Wagner, C. T. Schade, Advances in Powder Metallurgy and Particulate Materials 2005Part 7 pp 78-892L. A. Dobrzanski, Z. Brytan, M. Actis Grande, M. Rosso, Archives of Materials Science and Engineering, Vol 28Iss 4, April 2007 PP 217-2233L. A. Dobrzanski, Z. Brytan, M. Actis Grande, M. Rosso, Journal of Achievements in Materials and Manufacturing Engineering, Vol 17 Iss 1-2 pp 317-320 - Typical composition of wrought duplex stainless steel is Fe with 21-23 wt % Cr, 4.5-6.5 wt % Ni, 2.5-3.5 wt % Mo, and 0.08-0.2 wt % N, such as for SAF 2205. There are numerous patents for duplex stainless steel composition close to this composition. Almost all of the duplex stainless steels rely on the N content for increased corrosion resistance and increased strength. So far the commercial uses of sintered powder metallurgy (PM) duplex stainless steels are limited to the use of gas atomized fine powders that can be used for mainly HIP process. The main obstacle in using low cost water atomized powders for conventional PM use is increased N and possibility of intermetallic and carbide precipitation due to cooling rate during the sintering. Also conventional sintering needs some wetting agents or low temperature melting constituents to increase free energy and accelerate the kinetics of austenite phase precipitation within ferritic matrix.
- In the patent literature there are some documents disclosing sintered duplex stainless steel structures.
- SE538577C2 (Erasteel) discloses a sintered duplex stainless steel made from gas atomized powder and having a chemical composition with a max 0.030 wt % C, 4.5-6.5 wt % Ni, 0.21-0.29 wt % N, 3.0-3.5 wt % Mo, 21-24 wt % Cr, and optionally one or more of 0-1.0 wt % Cu, 0-1.0 wt % W, 0-2.0 wt % Mn, 0-1.0 wt % Si wherein N is equal or greater than 0.01*wt % Cr and the remaining elements are Fe and unavoidable impurities.
- EP0167822A1 (Sumitomo) discloses a sintered stainless steel comprising a matrix phase and a dispersed phase and a process for manufacturing. The dispersed phase is an austenite metallurgical structure and is dispersed throughout the matrix phase, which is comprised of an austenitic metallurgical structure having a steel composition different from that of the dispersed phase or a ferritic-austenitic duplex stainless steel.
- JP5263199A (Sumitomo) discloses production of a sintered stainless steel comprising a matrix phase and a dispersing phase. The method includes mixing a ferritic stainless steel powder with a powder selected from an austenitic stainless steel powder, an austenitic-ferritic duplex stainless steel powder, an austenitic-martensitic duplex stainless steel powder and austenitic-ferritic-martensitic stainless triple phase stainless steel powder. The powder mixture being compacted and sintered.
- EP0534864B1 (Sumitomo) discloses a sintered stainless steel having a content of N of 0.10-0.35 wt % and made from gas atomized steel powder having the same chemical composition as the sintered stainless steel.
- Almost all duplex grades available have N content between 0.18-0.40 wt % in order to balance austenite-ferrite balance in the structure and increase the strength. Although N content helps the above properties, it can pose hurdles in post processing, such as heat treatment and welding operations, by forming chromium nitrides, which limits the use of duplex stainless steels in many applications. In powder form, N increases the powder hardness making it less suitable for press and sinter applications.
- Embodiments of the invention overcome the problem with nitrides by avoiding the use of N in the chemistry, for example, having less than 0.10 wt % N or less than 0.07 wt % N, or less than 0.06 wt % N, or less than 0.05 wt % N, or less 0.04 wt % N, or less than 0.03 wt % N, and achieving phase balance and strength by alternative elements. Embodiments of the invention may enable production of water atomized powder with moderate compressibility for use in conventional press and sinter applications. Embodiments of this composition may also reduce precipitation of a deleterious ‘Sigma’ phase; irrespective of rate of cooling during sintering or annealing, mainly due to lower Mo content. Thus, minimizing post sintering heat treatments necessary to eliminate “Sigma” phase and minimizing sigma phase precipitation during welding.
- Embodiments of the composition may offer similar advantages when formed by gas atomization.
- Other than conventional PM, embodiments of the composition yield similar properties when processed with casting, direct metal deposition and additive manufacturing techniques.
- One object of certain embodiments of the invention is to provide an alloy powder for conventional PM that will produce a duplex structure during a sintering cycle.
- Another object of certain embodiments of the present invention is to provide a duplex sintered stainless steel.
- Another object of certain embodiments of the present invention is to obtain at least 35% higher tensile strength than ferritic steels such as 430L and double the corrosion resistance compared to austenitic steels such as 316L.
- Still another object of certain embodiments of the present invention is to provide a method for producing a duplex sintered stainless steel without the need of post sintering heat treatment.
- The above objectives may be accomplished by the following aspects and embodiments.
- In a first aspect of the present invention there is provided a stainless steel powder comprising, or consisting of, in weight percent:
-
- up to 0.1% of C,
- 0.5-3% of Si,
- up to 0.5% of Mn,
- 20-27% of Cr,
- 3-8% of Ni,
- 1-6% of Mo,
- up to 3% of W,
- up to 0.1% N,
- up to 4% of Cu,
- up to 0.04% of P,
- up to 0.04% of S,
- unavoidable impurities up to 0.8%,
- optionally one or more of up to 0.004% B, up to 1% Nb, up to 0.5% Hf, up to 1% Ti, up to 1% Co,
- rest Fe.
- The unavoidable impurities do not include the listed elements of C, Si, Mn, Cr, Ni, Mo, W, N, Cu, P, S, B, Nb, Hf, Ti, or Co. Unavoidable impurities may include impurities that cannot be controlled, or controlled with difficulty, during manufacture of steels. These can come from the raw materials used and also from the process. These include, Al, O, Mg, Ca, Ta, V, Te, or Sn. The unavoidable impurities may be up to 0.8%, up to 0.6%, up to 0.3%. An unavoidable impurity may be O. O may be present up to 0.6%, up to 0.4%, or up to 0.3%. Another unavoidable impurity may be Sn present up to 0.2%, content of Sn above 0.2% is in this context not regarded as an unavoidable impurity and thus will be regarded as intentionally added.
- In a preferred embodiment of the first aspect there is provided a stainless steel powder consisting of, in weight percent:
-
- up to 0.06% of C,
- 1-3% of Si,
- up to 0.3% of Mn,
- 23-27% of Cr,
- 4-7% of Ni,
- 1-3% of Mo,
- 0.8-1.5% of W,
- up to 0.07% N,
- 1-3% of Cu,
- up to 0.04% of P,
- up to 0.03% of S,
- unavoidable impurities up to 0.8%,
- optionally one or more of up to 0.004% B, up to 1% Nb, up to 0.5% Hf, up to 1% Ti, up to 1% Co,
- rest Fe.
- In another preferred embodiment of the first aspect there is provided a stainless steel powder comprising in weight percent:
-
- up to 0.03% of C,
- 1.5-2.5% of Si,
- up to 0.3% of Mn,
- 24-26% of Cr,
- 5-7% of Ni,
- 1-1.5% of Mo,
- 1-1.5% of W,
- up to 0.06% N,
- 1-3% of Cu,
- up to 0.02% of P,
- up to 0.015% of S,
- unavoidable impurities up to 0.8%,
- optionally one or more of up to 0.004% B, up to 1% Nb, up to 0.5% Hf, up to 1% Ti, up to 1% Co,
- rest Fe.
- In embodiments of the first aspect the powder is ferritic. For example, 99.5% ferritic. Slight amounts of austenite, e.g., up to 0.5% may be tolerated.
- In embodiments according to the first aspect the powder is produced by water atomization.
- In embodiments of the first aspect the powder is produced by gas atomization.
- In embodiments of the first aspect the particle size of the powder is between 53 microns and 18 microns such that at least 80 wt % of the particles are less than 53 microns and at most 20 wt % of the particles are less than 18 microns.
- In embodiments of the first aspect the particle size of the powder is between 26 microns and 5 microns such that at least 80 wt % of the particles are less than 26 microns and at most 20 wt % of the particles are less than 5 microns.
- In embodiments of the first aspect the particle size of the powder is between 150 microns and 26 microns such that at least 80 wt % of the particles are less than 150 microns and at most 20 wt % of the particles are less than 26 microns.
- In a second aspect of the present invention there is provided a method of producing a stainless steel powder according to the first aspect comprising the steps of:
-
- providing a molten metal of having a chemical composition corresponding to the chemical composition of the stainless steel powder according to the first aspect;
- subjecting a stream of the molten metal to water atomization; and
- recovery of the obtained stainless steel powder.
- In a third aspect of the present invention there is provided a sintered duplex stainless steel having a chemical composition according to the first aspect and embodiments thereof.
- In embodiments of the third aspect the Ni equivalent (Nieq) is such that 5<Nieq<11 and the Cr equivalent (Creq) is such that 27<Creq<38.
- In embodiments of the third aspect the pitting resistance equivalent number (PREN) is 28<PREN<33.
- In embodiments of the third aspect, the microstructure of the sintered duplex stainless steel is characterized by austenite phase precipitated within ferrite phase.
- In embodiments of the third aspect, the microstructure of the sintered duplex stainless steel contains 30-70% austenite and 30-70% ferrite. In embodiments of the third aspect, the microstructure of the sintered duplex stainless steel contains at least 99.5% austenite and ferrite, for example, at least 99.8% austenite and ferrite. The percentage of austenite and ferrite may be determined by ASTM E 562-11 and ASTM E 1245-03.
- In embodiments of the third aspect the microstructure of the sintered duplex stainless steel is characterized by being free from sigma phases and nitrides, for example, having less than 1% of sigma phases and nitrides.
- In a fourth aspect of the present invention there is provided a method for producing a sintered stainless steel comprising the steps of:
-
- providing a stainless steel powder according to the first aspect,
- optionally mixing the stainless steel powder with a lubricant and optionally other additives,
- subjecting the stainless steel powder or the mixture to a consolidation process forming a green component,
- subjecting the compacted green component to a sintering step in an inert or reducing atmosphere or in vacuum at a temperature between 1150° C. to 1450° C., preferably at a temperature between 1275° C. to 1400° C. for a period of time of 5 minutes to 120 minutes,
- subjecting the sintered component to a cooling step down to ambient temperature.
- Examples of an inert atmosphere include nitrogen, argon, and vacuum with argon backfill.
- An example of a reducing atmosphere is a hydrogen atmosphere, an atmosphere of a mixture of hydrogen and nitrogen, or an atmosphere of dissociated ammonia. In limited examples, carbon dioxide or carbon monoxide atmospheres may be used.
- In embodiments of the fourth aspect said consolidation process includes the steps of:
-
- uniaxial compaction at a compaction pressure of up to 900 MPa in a die to form a green component,
- ejecting the obtained compacted green component from the die.
- In embodiments of the fourth aspect said consolidation process includes one of: Metal Injection Molding (MIM), Hot Isostatic Pressing (HIP) or Additive Manufacturing techniques such as Binder Jetting.
- Methods according to the fourth aspect may include one of Laser Powder Bed Fusion (L-PBF), Direct Metal Laser Sintering (DMLS) or Direct Metal Deposition (DMD).
- In embodiments of the fourth aspect forced cooling or quenching is excluded from the cooling step.
- The effect of common alloying elements in stainless steels is well known. Cr is a major element in stainless steels which forms a Cr2O3 layer on the surface which then prevents further oxygen passing the layer, therefore providing an increased corrosion resistance. Ni is another major element which affects the properties of stainless steel. Ni increases the strength and toughness of the steel and also when present with Cr, enhances the corrosion resistance. Mo and W both impart the strength and toughness when present along with Ni. Mo also enhances the corrosion resistance along with Cr and Ni. Si acts as deoxidizer preventing O combining in the steel during melting, Si is also a strong ferrite former. Cu is austenite stabilizer. Cu also increases the corrosion resistance of stainless steel. Especially in conventional PM, Cu helps sintering by promoting liquid phase sintering.
- Embodiments of the invention provide a powder suitable for producing sintered duplex stainless steel, as well as the sintered stainless steel. The powder and the sintered stainless steel having a low or neglectable content of N. This eliminates the problem of formation of deleterious nitrides during fabrication of the sintered stainless steel. The sintered stainless steel is preferably produced from a compacted and sintered water-atomized powder since the low N content makes it possible to produce water-atomized powder with reasonable compressibility.
- Mo is normally present in stainless steel as it strongly promotes the resistance to both uniform and localized corrosion. Mo strongly stabilizes ferritic microstructure. At the same time Mo is prone to precipitate Mo rich “Sigma” and “Chi” phases at ferrite-austenite grain boundary. These are deleterious phases and affect strength and corrosion resistance adversely. However, due to lower Mo content in embodiments of the powder of the present invention, the possibility of forming sigma phase at any cooling rate is reduced, eliminating or reducing the need for the post processing heat treatment of annealing. This also means that the sigma phase will not likely form during welding operation, which is a common fabrication process for duplex stainless steels.
- Cr gives stainless steels their basic corrosion resistance and increases the resistance against high temperature corrosion.
- Ni promotes an austenitic microstructure and generally increases ductility and toughness. Ni has also a positive effect as it reduces the corrosion rate of stainless steels.
- Cu promotes an austenitic microstructure. The presence of Cu in the powder of the present invention facilitates the sintering process by enabling liquid phase sintering.
- W is expected to improve the resistance against pitting corrosion.
- Si increases strength and promotes a ferritic microstructure. It also increases oxidation resistance at high temperatures and in strongly oxidizing solutions at lower temperatures.
- When present in the powder according to certain embodiments of the present invention B, Nb, Hf, Ti, Co may enhance the properties. B when added in small % may help in liquid phase sintering. However, excess B, if present, may form borides, which are deleterious to both mechanical, and corrosion properties. Nb and Hf when present may stabilize the microstructure by preferentially combining with carbon forming fine carbides freeing Cr for the corrosion resistance. Ti in stainless steels may increase the tensile strength and toughness. Co increases the high temperature mechanical properties.
- Elements such as C, Mn, S and P should be kept at a level as low as possible in the powder of embodiments of the present invention as they may have a negative effect to various extent on compressibility of the powder and/or mechanical and corrosion preventive properties of the sintered component.
- Other elements, here designated as unavoidable impurities, may be tolerated up to a content of 0.8% by weight of the powder according to the present invention.
- The composition of the powder according to embodiments of the present invention is designed such that the produced powder will have fully (e.g., at least 99.5%) ferritic structure in the powder form and austenitic phase is precipitated out during sintering cycle. This will allow controlling the ratio of ferrite and austenite by adjusting the sintering parameters.
- Ni and Cr equivalents are calculated based on following empirical formulae:
-
Creq=Cr+2Si+1.5Mo+0.75W -
Nieq=Ni+0.5Mn+0.3Cu+25N+30C - Where Cr, Ni, etc. are the level of each element in the alloy in weight %.
- Further Pitting Resistance Equivalent Number is calculated as:
-
PREN=Cr+3.3Mo+16N - Where Cr, Mo and N are the level of each element in the alloy in weight %.
- The composition is targeted such that 5<Nieq<11 and 27<Creq<38. This places the alloy in at the border of Ferritic—Duplex region on Schaeffler Diagram. At this point the alloy is almost entirely ferritic (e.g., at least 99.5%). Elements like Mo, W and Si are supersaturated in the ferritic matrix.
- The powder of embodiments of the present invention may be produced by conventional powder manufacturing processes. Such processes may encompass melting of the raw materials followed by water or gas atomization, forming a so called prealloyed powder wherein all elements are homogeneously distributed within the iron matrix. A major advantage with a prealloyed powder in contrast to a premixed powder, wherein two or more powders are mixed together, is that segregation is avoided. Such segregation may cause variation in mechanical properties, corrosion resistance etc.
- When used for the production of sintered components, the powder of embodiments of the present invention may be compacted in a conventional uniaxial compaction equipment at a compaction pressure up to 900 MPa.
- Suitable particle size distribution of the stainless steel powder to be used at conventional uniaxial compaction is such that the particle size of the powder is between 53 microns and 18 microns such that at least 80 wt % of the particles are less than 53 microns and at most 20 wt % of the particles are less than 18 microns. Before compaction, the powder of embodiments of the present invention may be mixed with conventional lubricants, such as, but not limited to, Acrawax, Lithium Stearate, Intralube at a content up to 1 wt %. Other additives mixed in, up to 0.5 wt %, may be machinability enhancing agents such as CaF2, muscovite, bentonite or MnS.
- Other methods of consolidation techniques may be utilized such as Metal Injection Molding (MIM), Hot Isostatic Pressing (HIP), extrusion or Additive Manufacturing techniques such as Binder Jetting, Laser Powder Bed Fusion (L-PBF), Direct Metal Laser Sintering (DMLS) or Direct Metal Deposition (DMD)
- In a MIM process, suitable particle size distribution of the stainless steel powder to be used is such that the particle size of the powder is between 26 microns and 5 microns such that at least 80 wt % of the particles are less than 26 microns and at most 20 wt % of the particles are less than 5 microns.
- In a HIP or extrusion process suitable particle size distribution of the stainless steel powder to be used is such that the particle size of the powder is between 150 microns and 26 microns such that at least 80 wt % of the particles are less than 150 microns and at most 20 wt % of the particles are less than 26 microns.
- The particle size distribution may be measured by a conventional sieving operation according to ISO 4497:1983 or by laser diffraction (Sympatec) according to ISO 13320:1999.
- After compaction or consolidation, the compacted or consolidated body is subjected to a sintering process at sufficiently high temperatures in the range of 1150° C. to 1450° C., preferably at sufficiently high temperatures in the range of 1275° C. to 1400° C. for a period of time of 5 minutes to 120 minutes. Depending of shape and size of parts to be sintered, other period of sintering time such as 10 minutes to 90 minutes or 15 minutes to 60 minutes may be applied. The sintering atmosphere may be vacuum, inert or reducing such as a hydrogen atmosphere, an atmosphere of a mixture of hydrogen and nitrogen or dissociated ammonia. During the sintering process, the supersaturated elements in ferrite matrix precipitate out as an austenitic phase. Austenite will start precipitating out at the grain boundaries, will grow with further sintering and will precipitate within the grain itself.
- In contrast to other known duplex stainless steel materials, the composition of embodiments of the present invention should not form sigma phases or other hard and deleterious phases, e.g., Chi phase and nitrides, during cooling from an elevated temperature, irrespective of the cooling rate. For example, the amount of sigma phase or other hard and deleterious phases is less than 0.5%. Forced cooling or quenching is thus not necessary to apply. In this context forced cooling means that the sintered parts are subjected to a cooling gas at a pressure above atmospheric pressure. Quenching means that the sintered parts are submerged into a liquid cooling media.
- A microstructure as shown in
FIG. 1 will typically be formed containing ferrite and austenite. Presence of both phases is responsible for elevated mechanical and corrosion properties. No, or significantly limited amounts of, deleterious phases such as sigma and chi are formed during cooling which are normal for current known duplex stainless steels. As another consequence, this property will reduce or eliminate the formation of such phases during welding where the heat affected zone (HAZ) experience varying cooling rates. In another consequence, this composition will limit the precipitation of such phases during processes such as casting, extrusion, MIM, HIP and additive manufacturing. Embodiments of the invented alloy has shown mechanical and corrosion properties that are comparable to or exceeding the wrought and PM products manufactured with known duplex stainless steel alloys. - In summary, certain advantages of embodiments of this invention may include fewer tendencies to precipitate deleterious sigma and chi phases that affect the mechanical and corrosion properties. This is particularly of interest in welding. Most of the duplex stainless steel components are welded after they are formed. Welding imparts different cooling rates in different parts of HAZ. These cooling rates tend to precipitate sigma and chi phases along with nitrides due to nitrogen present in the current known alloys. Absence of these phases may eliminate the post heat treatments, which normally involve annealing at temperatures above 1200° C. followed by rapid cooling. This will in most cases becomes difficult when parts are welded to a bigger structure, limiting use of duplex stainless steel.
-
FIG. 1 shows the microstructure of invented sintered stainless steel, austenite and ferrite phases are present in equal proportions in as sintered condition, black spots are porosity. -
FIG. 2 discloses a comparison of ultimate tensile strength (UTS) and corrosion properties of the invented sintered stainless steel compared to 300 and 400 alloys, (SAE grades). -
FIG. 3 shows a comparison of mechanical properties of the invented sintered stainless steel at different sintering conditions - A stainless steel powder, having a particle size below 325 mesh, i.e. 95 wt % of the particles passed 45 μm sieve, was mixed with 0.75 wt % of Acrawax as a lubricant. The chemical analysis of the stainless steel powder was 0.01 wt % C, 1.52 wt % Si, 0.2 wt % Mn, 0.013 wt % P, 0.008 wt % S, 24.9 wt % Cr, 2.0 wt % Cu, 1.3 wt % Mo, 1.0 wt % W, 0.05 wt % N, balance Fe.
- The obtained powder mixture was pressed in a uniaxial press and compacted into transverse rapture strength (TRS) bars, according to ASTM B528-16 at a compaction pressure of 750 MPa. The pressed TRS bars were then sintered in 100% hydrogen atmosphere at 1343° C. with ramp rate of 7° C./minute for 45 minutes. This was followed by furnace cooling at rate 5° C./minute. The samples were then mounted and polished for microstructure examination. The polished samples were then electro-etched with 33% NaOH at 3V for 15 sec. Electro-etch with NaOH reveals the ferrite phase as tan, austenite as white (unaffected) and sigma phases in dark orange at grain boundaries within ferrite matrix. The microstructure observed is as shown in
FIG. 1 . The microstructure shows approximately 50/50 mixture of ferrite (tan) and austenite (white). There is no sign of any sigma phase (dark orange) in the microstructure. The black spots are porosity in the sample. - Various stainless steel powders according to embodiments of the invention, and as comparative samples, were produced by water atomizing. The chemical composition of the stainless steel powders are shown in table 1. Stainless steel melts having various chemical compositions were melted in an induction furnace, the molten metal was subjected to water stream to obtain steel powder. The obtained powders was then dried and screened to −325 mesh. The screened powder was −45 microns i.e. 95 wt % of the powder particles were less than 45 microns. The powders were then mixed with 0.75 wt % of the lubricant Acrawax.
- In order to test the mechanical properties i.e. ultimate tensile strength (UTS), yield strength (YS) and elongation, TS samples (dog bone) per ASTM B925-15 were pressed with a compaction pressure of 750 MPa. The bars were then sintered as mentioned in Example 1. The sintered bars were then tested for mechanical properties per ASTM E8/E8M-16a. Metallographic examination was also conducted in order to establish the ratio between austenite and ferrite in sintered samples. The test results are shown in table 2 in comparison with published data from samples of known duplex stainless steels in wrought, (DSS 329 Wrought), and gas atomized and hipped conditions (DSS 329 PM GA).
- Table 2 shows that the stainless steel powders according to the present invention can be used for producing sintered duplex stainless steel having desired mechanical properties.
-
TABLE 1 chemical compositions of various stainless steel powders, there production method and type of process for producing sintered samples. Chemical analysis [% by weight] Sample Type C Si Mn S P Cr Ni Mo W Cu O N Other Comparative DSS 329 Wrought 0.08 1.00 23-28 2.5-5 1-2 0.08 Wrought steel Comparative DSS 329 Water 0.20 0.75 1.00 23-28 2.5-5 1-2 0.05 0.08 PM WA atomized powder, HIP Comparative DSS Gas 0.03 1.00 2.00 0.020 0.030 22.0-23.0 4.5-6.5 3.0-3.5 0.75 0.14-0.20 2205 atomized PM GA powder HIP Premix XSS DP1 Water 0.03 2.00 0.10 0.006 0.008 25 5.5 1.3 1 2 0.2 0.06 PM WA atomized Premix powders4, compacted and sintered Invention XSS DP1 Water 0.01 1.52 0.20 0.013 0.008 24.9 5.5 1.3 1 2 0.15 0.05 PM WA atomized Prealloy powder, prealloyed compacted and sintered Invention XSS Water 0.03 1.97 0.10 0.007 0.012 23.4 5.1 1.2 0.9 1.9 0.13 0.05 DP1-1 atomized powder, prealloyed compacted and sintered Invention XSS Water 0.03 2.12 0.20 0.007 0.012 26.1 5.2 1.3 0.9 3 0.15 0.02 DP1-2 atomized powder, prealloyed compacted and sintered Invention XSS Water 0.03 1.94 0.20 0.008 0.013 25.1 5.6 1.2 0.8 2 0.15 0.02 0.58 Nb DP1-3 atomized powder, prealloyed compacted and sintered Comparative XSS Water 0.03 2.14 0.20 0.009 0.015 22.3 5.2 1.3 0.9 1.9 0.16 0.06 0.6 Sn DP1-4 atomized powder, prealloyed compacted and sintered 4Premix of 316L, 434L and elemental powders of Si, W and Cu. -
TABLE 2 mechanical properties and metallographic structure for sintered samples produced from stainless steel powders according to table 1. Mechanical Properties Sintering time TS YS TRS Elongation % austenite in Sample Type [minutes] [Mpa] [Mpa] [Mpa] [%] ferrite matrix Comparative DSS 329 Wrought steel Annealed 725 550 25 ~50 Wrought Comparative DSS 329 PM WA Water atomized powder, HIP 45 523 460 180 7 0 Comparative DSS 2205 PM GA Gas atomized powder, HIP 45 578 427 200 11 ~50 Comparative XSS DP1 PM WA Water atomized powders5, compacted 45 720 700 220 2.5 ~35 Premix and sintered Invention XSS DP1 PM WA Water atomized powder, prealloyed 45 776 617 278 8.6 ~60 Prealloy compacted and sintered Invention XSS DP1-1 Water atomized powder, prealloyed 45 727 504 275 11.0 ~50 compacted and sintered Invention XSS DP1-2 Water atomized powder, prealloyed 45 809 745 265 2.5 ~50 compacted and sintered Invention XSS DP1-3 Water atomized powder, prealloyed 45 843 691 257 6.5 ~45 compacted and sintered Comparative XSS DP1-4 Water atomized powder, prealloyed 45 749 743 218 0.5 ~10 compacted and sintered 5Premix of 316L, 434L and elemental powders of Si, W and Cu. - An embodiment of the invented powder with composition as in Example 1 was also sintered at various temperatures and atmospheres below, to show the effect on mechanical properties. Such data is plotted in
FIG. 3 . -
- A. 2500° F. for 45 minutes in hydrogen gas
- B. 2450° F. for 45 minutes in hydrogen gas
- C. 2450° F. for 60 minutes in hydrogen gas
- D. 2300° F. for 60 minutes in hydrogen gas
- E. 2250° F. for 60 minutes in hydrogen gas
- F. 2250° F. for 60 minutes in dissociated ammonia
- In order to perform corrosion test, TRS bars as in Example 1 were produced along with bars for 316L and 434L as representatives from austenitic and ferritic grades. The samples were then tested for corrosion in 5% NaCl solution at room temperature per ASTM B895-16. The corrosion was compared by the hours takes for onset of corrosion on the samples. The comparative data is plotted in
FIG. 2 along with the UTS and YS for these samples. The diameter of the bubbles in theFIG. 3 represents the number of hours taken for the start of the corrosion on the samples. The corrosion test for the invented powder was discontinued after 3700 hours as there was no sign of corrosion and it already exceeded 3 times that of 316L samples.
Claims (18)
Creq=Cr+2Si+1.5Mo+0.75W
Nieq=Ni+0.5Mn+0.3Cu+25N+30C and,
PREN=Cr+3.3Mo+16N and,
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP16202574.6A EP3333275B1 (en) | 2016-12-07 | 2016-12-07 | Stainless steel powder for producing sintered duplex stainless steel |
EP16202574.6 | 2016-12-07 | ||
PCT/EP2017/081234 WO2018104179A1 (en) | 2016-12-07 | 2017-12-01 | Stainless steel powder for producing duplex sintered stainless steel |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2017/081234 A-371-Of-International WO2018104179A1 (en) | 2016-12-07 | 2017-12-01 | Stainless steel powder for producing duplex sintered stainless steel |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US18/541,524 Division US20240117478A1 (en) | 2016-12-07 | 2023-12-15 | Stainless steel powder for producing duplex sintered stainless steel |
Publications (1)
Publication Number | Publication Date |
---|---|
US20190309399A1 true US20190309399A1 (en) | 2019-10-10 |
Family
ID=57517775
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US16/467,267 Abandoned US20190309399A1 (en) | 2016-12-07 | 2017-12-01 | Stainless steel powder for producing duplex sintered stainless steel |
US18/541,524 Pending US20240117478A1 (en) | 2016-12-07 | 2023-12-15 | Stainless steel powder for producing duplex sintered stainless steel |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US18/541,524 Pending US20240117478A1 (en) | 2016-12-07 | 2023-12-15 | Stainless steel powder for producing duplex sintered stainless steel |
Country Status (16)
Country | Link |
---|---|
US (2) | US20190309399A1 (en) |
EP (2) | EP3333275B1 (en) |
JP (1) | JP7028875B2 (en) |
KR (1) | KR102408835B1 (en) |
CN (1) | CN110168122A (en) |
AU (1) | AU2017370993B2 (en) |
BR (1) | BR112019011395B1 (en) |
CA (1) | CA3046282A1 (en) |
DK (1) | DK3333275T3 (en) |
ES (1) | ES2848378T3 (en) |
MX (1) | MX2019006609A (en) |
PL (1) | PL3333275T3 (en) |
RU (1) | RU2753717C2 (en) |
TW (1) | TWI760395B (en) |
WO (1) | WO2018104179A1 (en) |
ZA (1) | ZA201903576B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112846168A (en) * | 2020-12-29 | 2021-05-28 | 上海富驰高科技股份有限公司 | Non-magnetic high-strength stainless steel material and metal injection molding preparation method thereof |
CN114107827A (en) * | 2021-12-08 | 2022-03-01 | 福州大学 | Duplex stainless steel powder for 3D printing and preparation and printing methods thereof |
CN114855092A (en) * | 2022-07-05 | 2022-08-05 | 北京科技大学 | Additive manufacturing high-strength and high-toughness stainless steel and preparation process thereof |
US11939646B2 (en) | 2018-10-26 | 2024-03-26 | Oerlikon Metco (Us) Inc. | Corrosion and wear resistant nickel based alloys |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP7400218B2 (en) * | 2018-08-31 | 2023-12-19 | 大同特殊鋼株式会社 | Alloy powder composition |
EP3640352A1 (en) * | 2018-10-17 | 2020-04-22 | AB Sandvik Materials Technology | Method of producing tube of duplex stainless steel |
JP6960099B2 (en) * | 2019-09-20 | 2021-11-05 | 日立金属株式会社 | Manufacturing method of alloy members |
CN110629131A (en) * | 2019-09-26 | 2019-12-31 | 上海镭镆科技有限公司 | 3D printing stainless steel material, preparation method and application |
EP4249150A1 (en) * | 2022-03-25 | 2023-09-27 | Siemens Aktiengesellschaft | Sintered metal component |
CN114959508B (en) * | 2022-07-28 | 2022-10-21 | 北京科技大学 | Stainless steel and preparation method thereof |
CN116219295B (en) * | 2023-03-10 | 2024-05-10 | 天津大学 | Double-phase stainless steel powder for laser additive manufacturing and method for manufacturing double-phase stainless steel by in-situ laser additive |
CN117867412B (en) * | 2024-03-08 | 2024-05-10 | 东北大学 | High corrosion resistance stainless steel for fuel cell bipolar plate |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3696486A (en) * | 1969-08-25 | 1972-10-10 | Int Nickel Co | Stainless steels by powder metallurgy |
US3859086A (en) * | 1971-12-30 | 1975-01-07 | Int Nickel Co | Method of enhancing powder compactibility |
US5302214A (en) * | 1990-03-24 | 1994-04-12 | Nisshin Steel Co., Ltd. | Heat resisting ferritic stainless steel excellent in low temperature toughness, weldability and heat resistance |
US5623726A (en) * | 1994-07-11 | 1997-04-22 | Rauma Materials Technology Oy | Roll manufacture |
US20030133824A1 (en) * | 2001-09-21 | 2003-07-17 | Masami Taguchi | High-toughness and high-strength ferritic steel and method of producing the same |
Family Cites Families (30)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT1042949B (en) | 1975-09-29 | 1980-01-30 | Montedison Spa | PROCESS FOR THE PREPARATION OF IRON OXIDE THERMO-STABLE PIGMENTS FROM ACID SOLUTIONS CONTAINING FERROUS SULPHATE |
AT360061B (en) * | 1976-01-13 | 1980-12-29 | Graenges Nyby Ab | METHOD FOR PRODUCING STABILIZED, FERRITIC, STAINLESS STEEL CHROME STEELS |
DE2851274A1 (en) * | 1977-11-29 | 1979-05-31 | British Steel Corp | CHROME-CONTAINING METAL POWDER |
JPS60190552A (en) * | 1984-03-12 | 1985-09-28 | Sumitomo Metal Ind Ltd | Sintered stainless steel and its manufacture |
EP0167822B1 (en) | 1984-06-06 | 1989-08-30 | Sumitomo Metal Industries, Ltd. | Sintered stainless steel and production process therefor |
JPS6152302A (en) * | 1984-08-20 | 1986-03-15 | Daido Steel Co Ltd | Alloy steel powder for powder metallurgy |
US4708741A (en) * | 1986-06-13 | 1987-11-24 | Brunswick Corporation | Rapid sintering feedstock for injection molding of stainless steel parts |
JPH0663055B2 (en) | 1990-12-20 | 1994-08-17 | 住友金属工業株式会社 | Sintered stainless steel |
JP3227734B2 (en) | 1991-09-30 | 2001-11-12 | 住友金属工業株式会社 | High corrosion resistant duplex stainless steel and its manufacturing method |
JPH08246008A (en) * | 1995-03-08 | 1996-09-24 | Daido Steel Co Ltd | Metal powder and its production by water atomization |
SE9702299D0 (en) | 1997-06-17 | 1997-06-17 | Hoeganaes Ab | Stainless steel powder |
JP3856294B2 (en) * | 2001-11-30 | 2006-12-13 | セイコーエプソン株式会社 | Stainless steel powder for sintering, granulated powder for manufacturing sintered stainless steel, and sintered stainless steel |
BRPI0406423B1 (en) | 2003-08-07 | 2012-12-11 | duplex stainless steel and its production method. | |
US20050129563A1 (en) * | 2003-12-11 | 2005-06-16 | Borgwarner Inc. | Stainless steel powder for high temperature applications |
SE529041C2 (en) * | 2005-08-18 | 2007-04-17 | Erasteel Kloster Ab | Use of a powder metallurgically made steel |
SE528991C2 (en) * | 2005-08-24 | 2007-04-03 | Uddeholm Tooling Ab | Steel alloy and tools or components made of the steel alloy |
TWI394848B (en) * | 2007-10-10 | 2013-05-01 | Nippon Steel & Sumikin Sst | Two-phase stainless steel wire rod, steel wire, bolt and manufacturing method thereof |
US8313691B2 (en) * | 2007-11-29 | 2012-11-20 | Ati Properties, Inc. | Lean austenitic stainless steel |
JP4531118B2 (en) * | 2008-05-27 | 2010-08-25 | 新日鐵住金ステンレス株式会社 | Flux-cored wire for welding duplex stainless steel to refine solidified grains |
CN101338385A (en) * | 2008-08-29 | 2009-01-07 | 安泰科技股份有限公司 | Nitrogen-containing/high nitrogen stainless steel products and method for preparing same |
KR20170141269A (en) | 2009-10-16 | 2017-12-22 | 회가내스 아베 (피유비엘) | Nitrogen containing, low nickel sintered stainless steel |
KR20120132691A (en) * | 2010-04-29 | 2012-12-07 | 오또꿈뿌 오와이제이 | Method for manufacturing and utilizing ferritic-austenitic stainless steel with high formability |
EP2576104A4 (en) * | 2010-06-04 | 2017-05-31 | Höganäs Ab (publ) | Nitrided sintered steels |
EP2511031A1 (en) * | 2011-04-12 | 2012-10-17 | Höganäs Ab (publ) | A powder metallurgical composition and sintered component |
FI126574B (en) * | 2011-09-07 | 2017-02-28 | Outokumpu Oy | Duplex stainless steel |
CN104919072B (en) * | 2013-01-15 | 2017-07-14 | 株式会社神户制钢所 | Two phase stainless steel steel and two phase stainless steel steel pipe |
KR101496000B1 (en) * | 2013-05-03 | 2015-02-25 | 주식회사 포스코 | Method for manufacturing hot rolled steel sheet of lean duplex stainless steels |
JP6152302B2 (en) * | 2013-06-04 | 2017-06-21 | 錦城護謨株式会社 | Anchor mounting device for drain material |
JP6378517B2 (en) * | 2014-03-27 | 2018-08-22 | 山陽特殊製鋼株式会社 | Precipitation hardening type stainless steel powder and sintered body thereof that have excellent anti-sintering cracking properties and high strength after sintering-aging treatment. |
SE538577C2 (en) | 2014-05-16 | 2016-09-27 | Powder metallurgical duplex stainless steel |
-
2016
- 2016-12-07 ES ES16202574T patent/ES2848378T3/en active Active
- 2016-12-07 PL PL16202574T patent/PL3333275T3/en unknown
- 2016-12-07 EP EP16202574.6A patent/EP3333275B1/en active Active
- 2016-12-07 DK DK16202574.6T patent/DK3333275T3/en active
-
2017
- 2017-12-01 MX MX2019006609A patent/MX2019006609A/en unknown
- 2017-12-01 CN CN201780082430.4A patent/CN110168122A/en active Pending
- 2017-12-01 US US16/467,267 patent/US20190309399A1/en not_active Abandoned
- 2017-12-01 BR BR112019011395-9A patent/BR112019011395B1/en active IP Right Grant
- 2017-12-01 EP EP17808459.6A patent/EP3551775B1/en active Active
- 2017-12-01 JP JP2019530467A patent/JP7028875B2/en active Active
- 2017-12-01 KR KR1020197019317A patent/KR102408835B1/en active IP Right Grant
- 2017-12-01 CA CA3046282A patent/CA3046282A1/en active Pending
- 2017-12-01 RU RU2019121005A patent/RU2753717C2/en active
- 2017-12-01 WO PCT/EP2017/081234 patent/WO2018104179A1/en unknown
- 2017-12-01 AU AU2017370993A patent/AU2017370993B2/en active Active
- 2017-12-07 TW TW106142944A patent/TWI760395B/en active
-
2019
- 2019-06-04 ZA ZA2019/03576A patent/ZA201903576B/en unknown
-
2023
- 2023-12-15 US US18/541,524 patent/US20240117478A1/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3696486A (en) * | 1969-08-25 | 1972-10-10 | Int Nickel Co | Stainless steels by powder metallurgy |
US3859086A (en) * | 1971-12-30 | 1975-01-07 | Int Nickel Co | Method of enhancing powder compactibility |
US5302214A (en) * | 1990-03-24 | 1994-04-12 | Nisshin Steel Co., Ltd. | Heat resisting ferritic stainless steel excellent in low temperature toughness, weldability and heat resistance |
US5623726A (en) * | 1994-07-11 | 1997-04-22 | Rauma Materials Technology Oy | Roll manufacture |
US20030133824A1 (en) * | 2001-09-21 | 2003-07-17 | Masami Taguchi | High-toughness and high-strength ferritic steel and method of producing the same |
Non-Patent Citations (1)
Title |
---|
D. A. Melford, "The influence of residual and trace elements on hot shortness and high temperature embrittlement," Philosophical Transactions of The Royal Society of London, Series A: Mathematical, Physical & Engineering Sciences, 295 (1980), pp. 89-103. (Year: 1980) * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11939646B2 (en) | 2018-10-26 | 2024-03-26 | Oerlikon Metco (Us) Inc. | Corrosion and wear resistant nickel based alloys |
CN112846168A (en) * | 2020-12-29 | 2021-05-28 | 上海富驰高科技股份有限公司 | Non-magnetic high-strength stainless steel material and metal injection molding preparation method thereof |
CN114107827A (en) * | 2021-12-08 | 2022-03-01 | 福州大学 | Duplex stainless steel powder for 3D printing and preparation and printing methods thereof |
CN114855092A (en) * | 2022-07-05 | 2022-08-05 | 北京科技大学 | Additive manufacturing high-strength and high-toughness stainless steel and preparation process thereof |
Also Published As
Publication number | Publication date |
---|---|
EP3551775A1 (en) | 2019-10-16 |
EP3333275A1 (en) | 2018-06-13 |
KR102408835B1 (en) | 2022-06-13 |
ZA201903576B (en) | 2020-12-23 |
PL3333275T3 (en) | 2021-05-17 |
MX2019006609A (en) | 2019-08-01 |
TWI760395B (en) | 2022-04-11 |
CA3046282A1 (en) | 2018-06-14 |
AU2017370993B2 (en) | 2023-05-11 |
EP3333275B1 (en) | 2020-11-11 |
ES2848378T3 (en) | 2021-08-09 |
WO2018104179A1 (en) | 2018-06-14 |
DK3333275T3 (en) | 2021-02-08 |
RU2753717C2 (en) | 2021-08-20 |
KR20190092493A (en) | 2019-08-07 |
EP3551775B1 (en) | 2021-06-23 |
BR112019011395B1 (en) | 2023-10-31 |
US20240117478A1 (en) | 2024-04-11 |
TW201833346A (en) | 2018-09-16 |
AU2017370993A1 (en) | 2019-06-20 |
BR112019011395A2 (en) | 2019-10-15 |
CN110168122A (en) | 2019-08-23 |
JP7028875B2 (en) | 2022-03-02 |
RU2019121005A (en) | 2021-01-11 |
JP2020509167A (en) | 2020-03-26 |
RU2019121005A3 (en) | 2021-04-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20240117478A1 (en) | Stainless steel powder for producing duplex sintered stainless steel | |
US8623108B2 (en) | Wear-resistant material | |
JP6093405B2 (en) | Nitrogen-containing low nickel sintered stainless steel | |
TWI542707B (en) | Iron based powders for powder injection molding | |
JP6227871B2 (en) | Master alloy for producing sintered hardened steel parts and process for producing sintered hardened parts | |
JP2012527535A (en) | High strength low alloy sintered steel | |
US10094007B2 (en) | Method of manufacturing a ferrous alloy article using powder metallurgy processing | |
TW201037092A (en) | Iron vanadium powder alloy | |
US20160001369A1 (en) | Method for producing powder metal compositions for wear and temperature resistance applications and method of producing same | |
EP2969327A1 (en) | Powder metal compositions for wear and temperature resistance applications and method of producing same | |
Samal et al. | Processing and properties of PM 440C stainless steel | |
JPH08218101A (en) | Steel powdery mixture for powder metallurgy and material for sintering containing the same | |
ES2357175T3 (en) | COMPOSITION IN METALLURGICAL POWDER AND PRODUCTION METHOD. | |
Warzel III et al. | Vanadium as an Alloying Element in Powder Metallurgy Steels | |
JPH0459362B2 (en) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HOGANAS AB (PUBL), SWEDEN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BADWE, SUNIL;REEL/FRAME:049414/0879 Effective date: 20190601 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: FINAL REJECTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: FINAL REJECTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: ADVISORY ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO PAY ISSUE FEE |