EP1131472A1 - Acier inoxydable austenitique cr-mn-ni-cu - Google Patents

Acier inoxydable austenitique cr-mn-ni-cu

Info

Publication number
EP1131472A1
EP1131472A1 EP99958707A EP99958707A EP1131472A1 EP 1131472 A1 EP1131472 A1 EP 1131472A1 EP 99958707 A EP99958707 A EP 99958707A EP 99958707 A EP99958707 A EP 99958707A EP 1131472 A1 EP1131472 A1 EP 1131472A1
Authority
EP
European Patent Office
Prior art keywords
alloy
max
set forth
molybdenum
chromium
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.)
Withdrawn
Application number
EP99958707A
Other languages
German (de)
English (en)
Inventor
John H. Magee, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CRS Holdings LLC
Original Assignee
CRS Holdings LLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by CRS Holdings LLC filed Critical CRS Holdings LLC
Publication of EP1131472A1 publication Critical patent/EP1131472A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • 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
    • C22C38/18—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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys

Definitions

  • This invention relates to Cr-Mn austenitic stainless steels, and in particular to a Cr-Mn-Ni-Cu austenitic stainless steel having a unique combination of corrosion resistance in chloride-containing environments, hot workability, and resistance to work hardening
  • a known austenitic stainless steel has the following we: composition
  • an austenitic stainless steel that provides pitting and crevice corrosion resistance comparable to Type 304 stainless steel, but which has acceptable hot workability so that it can be readily formed into a va ⁇ ety of product shapes.
  • the present invention provides an austenitic stainless steel alloy having the broad, intermediate, and preferred compositional ranges set forth below in weight percent.
  • the elements are balanced to provide the unique combination of properties that are characte ⁇ stic of the alloy according to this invention More specifically, the combined amount of chromium and molybdenum is maintained below about 17.75 wt.%; the combined amount of carbon and nitrogen is at least about 0.19 wt.%; and the alloy composition is balanced such that it contains not more than about 9% by volume (vol %) fer ⁇ te in the as-cast condition.
  • the chromium, molybdenum, and nitrogen are carefully balanced in accordance with the following relationship %Cr + 3.3(%Mo) + 13(%N) > 20.5 This relationship defines the pitting resistance equivalent number (PRE) for this alloy
  • the PRE for this alloy is greater than about 21.0.
  • chromium is present to benefit the general corrosion resistance of the alloy Chromium also cont ⁇ butes to the chlo ⁇ de corrosion resistance of this alloy.
  • the amount of chromium in the alloy is rest ⁇ cted to not more than about 17.5%. better yet to not more than about 17.0% and preferably to not more than about 16.75% because too much chromium adversely affects the hot workability of the alloy.
  • At least about 0.25%, better yet at least about 0.5%, and preferably at least about 0.7% molybdenum is present in this alloy because it too benefits the chlo ⁇ de corrosion resistance of the alloy.
  • the amount of molybdenum in this alloy is rest ⁇ cted to not more than about 1.5%, better yet to not more than about 1.2%, and preferably to not more than about 1.0%.
  • Chromium and molybdenum are both fer ⁇ te forming elements in this alloy Too much fer ⁇ te adversely effects the hot-workability of this alloy Therefore, chromium and molybdenum are rest ⁇ cted to avoid the formation of a delete ⁇ ous amount of fer ⁇ te.
  • the combined amount of chromium and molybdenum (%Cr + %Mo) in this alloy is not greater than about 17.75%, and preferably, not more than about 17 5%.
  • the alloy contains at least about 0.05%, better yet at least about 0.10%, and preferably at least about 0.12% nitrogen
  • the alloy contains not more than about 0 30%, better yet not more than about 0.25%, and preferably not more than about 0.20% nitrogen.
  • Carbon also benefits the austenitic phase balance of this alloy Accordingly, at least about 0 025%, better yet at least about 0.05%, and preferably at least about 0.08% carbon is present in this alloy. Too much carbon leads to carbide precipitation which adversely affects the corrosion resistance and cold formabihty of the alloy Therefore, the amount of carbon is rest ⁇ cted to not more than about 0.15%, better yet to not more than about 0.12%, and preferably to not more than about 0.11% in this alloy.
  • the alloy contains a combined amount of carbon and nitrogen (%C + %N) of at least about 0.19%, and preferably, at least about 0.25%, to avoid the formation of a deleterious amount of ferrite.
  • At least about 1%, better yet at least about 1.5%, and preferably at least about 2.0% nickel is present in this alloy to benefit the austenitic phase balance of the alloy.
  • Nickel also contributes to the low work hardening rate of the alloy, and thus benefits the good cold formability of the alloy.
  • Nickel is restricted to not more than about 4%, better yet to not more than about 3.5%, and preferably to not more than about 3.0% in this alloy.
  • Copper is present in this alloy because it lowers the work hardening rate of the alloy to an even greater extent than nickel. Thus, it is highly beneficial to the good cold formability of this alloy. Copper also benefits the cold formability of this alloy because it lowers the annealed strength provided by this alloy. To achieve those desired properties the alloy contains at least about 1.5%, e.g., at least about 1.6 or 1.7% copper. Better yet, the alloy contains at least about 2.0%, and preferably at least about 2.5% copper. The amount of copper is restricted because too much copper causes hot shortness, especially when the amount of ferrite in the as-cast alloy is about 9 vol.% or more. Hot shortness results in severe cracking and/or tearing of the alloy during hot working.
  • the alloy contains not more than about 4%, better yet not more than about 3.5%, and preferably not more than about 3.0% copper.
  • the composition is balanced so that the alloy contains less than about 9 vol.% ferrite in the as-cast condition.
  • the alloy is preferably balanced such that it contains not more than about 8.5 vol.% ferrite in the as-cast condition, better yet not more than about 7 vol.% ferrite, and for best results, not more than about 6 vol.% ferrite.
  • At least about 4%, better yet at least about 6%, and preferably at least about 7% manganese is present in this alloy because it contributes to austenite stability, i.e., it helps to stabilize the austenite against transformation to martensite during mechanical deformation.
  • Manganese also contributes to the retention of nitrogen in the alloy by increasing the solubility limit of nitrogen in the solid solution.
  • the alloy contains not more than about 12%, better yet not more than about 10%, and preferably not more than about 9% manganese because too much manganese leads to the formation of ferrite which is undesirable in this alloy.
  • a small quantity of silicon may be present in this alloy as a retained amount from deoxidizing additions during melting.
  • the amount of silicon present in the alloy is restricted to not more than about 1.0%, better yet to not more than about 0.75%, and preferably to not more than about 0.50% because silicon is a ferrite forming element in this steel.
  • tungsten can be present in this alloy to benefit the chloride co ⁇ osion resistance of the alloy.
  • the amount of tungsten in the alloy is preferably restricted to not more than about 0.75 % because tungsten is also a ferrite former in this alloy and too much tungsten adversely affects the hot workability of the alloy.
  • cobalt up to about 1.0% or 0.75% may also be present in this alloy. When present, cobalt provides benefits similar to those provided by nickel and copper.
  • a small amount of phosphorus, up to about 0.2% or 0.1%, and/or a small amount of sulfur, up to about 0.1% or 0.05%, may be present in this alloy when desired to benefit the machinability of the alloy.
  • the amounts of phosphorus and sulfur are preferably restricted because they adversely affect the corrosion resistance and formability of the alloy. Accordingly, phosphorus is preferably restricted to not more than about 0.05% and sulfur is preferably restricted to not more than about 0.025% to obtain good formability. For optimum formability, sulfur is restricted to not more than about 0.01%, and preferably to not more than about 0.005% in this alloy.
  • the balance of the alloy is essentially iron except for the usual impurities found in commercial grades of steels intended for similar service. No special techniques are required in melting, casting, or working the alloy of this invention. Arc melting followed by argon-oxygen decarburization is the preferred method of melting and refining the alloy, but other practices such as vacuum melting can be employed. In addition, this alloy can be made using powder metallurgy techniques, such as powder injection molding and metal injection molding techniques. This alloy can also be prepared using continuous casting methods.
  • the alloy of the present invention can be formed into a variety of shapes for a wide variety of uses.
  • Preferred product forms include billets, bars, rod, wire, strip, plate, and sheet.
  • the formability properties of this alloy are such that it readily lends itself to cold formed articles such as cold-drawn wire or rod.
  • useful articles may be easily formed by cold bending or flattening the wire or rod that has been prepared from this alloy.
  • Examples 1 and 2 having the compositions in weight percent shown in Table 1 were prepared and tested.
  • comparative Heats A-L with compositions outside the range of the present invention were also prepared and tested. Their weight percent compositions are also shown in Table 1.
  • Heats A, F, and G are representative of the alloy desc ⁇ bed in U.S. Patent No. 5,268,510. Heats B-E and H-K are similar to Heats A, F, and G, but contain different levels of carbon, copper, nickel, molybdenum, and/or nitrogen. Heat L is representative of a commercial grade of Type 304 stainless steel.
  • Example 1 and Heats B to K were induction melted under a cover of argon gas and cast into 2% inch square ingots each weighing 17 lbs. The ingots were forged at 2200 °F to 1 inch square bars. A 4" long piece was taken from each of the bars and was milled to 7/8" x 1 ".
  • Heat A was prepared as a continuously-cast production size heat which was cast as 5" square billet. An 8" long section was cut from the billet and press forged at 2200°F to 2 1 /.” square bar, reheated, and then forged to 1-1/16" square bar. A 4" long piece was cut from the 1-1/16" bar, milled to 7/8" x 1-1/16", and then hot rolled to 0.250" thick strip. The st ⁇ p mate ⁇ al was annealed at 1950°F for 1 hour, water quenched, cleaned, and then cold rolled to 0.140" thick st ⁇ p. That mate ⁇ al was annealed at 1950°F for 15 minutes and water quenched. Test specimens for crevice corrosion testing were prepared from the annealed mate ⁇ al. Example 2 was induction melted under a cover of argon gas and cast as a
  • Specimens for crevice corrosion testing were prepared from the 0.140" annealed st ⁇ p mate ⁇ al. Duplicate specimens of Examples 1 and 2 and Comparative Heats A-C, E-I, and L were tested in a solution of 5% FeCl 3 and 1% NaNO 3 for 24 hours at 10 °C. If no pitting attack was observed after the first 24 hour period, then the specimen was ground and tested again at a temperature 5C° higher than the previous test temperature. Testing continued in this manner until pitting attack was observed on the specimen. The critical corrosion temperature is the highest temperature at which the specimen did not sustain any pitting.
  • Table 2 Set forth in Table 2 below are the results of critical co ⁇ osion temperature testing of each of duplicate specimens of the examples and comparative heats in Table 1. The results are presented as the critical corrosion temperature (CCT) in °C for each specimen. Also shown in Table 2 are the Cr, Mo, and N content of each example and comparative heat and the pitting resistance equivalence number (PRE) for each example and comparative heat.
  • CCT critical corrosion temperature
  • PRE pitting resistance equivalence number
  • Example 1 and 2 of the alloy according to this invention provide better resistance to chloride induced corrosion than any of the comparative heats (Heats A-C and E-I).
  • Type 304 stainless steel (Heat L) has slightly better chloride corrosion resistance than Examples 1 and 2.
  • Salt spray testing was performed on a limited number of wire specimens of Example 2 and Heat A. The 0.264" diameter specimens were obtained from production material that was hot rolled to 0.306" round, annealed, cleaned, and then cold drawn to 0.264" round. The wire specimens were exposed to a 5%NaCl solution at 95 °F for 466 hours.
  • Table 3 Set forth in Table 3 below are the results of a work-hardening study performed on annealed strip for several of the examples from Table 1 above including the percent cold reduction per pass (% CR.) and the Rockwell hardness readings obtained after each reduction.
  • HRB Rockwell B Scale
  • HRC Rockwell C Scale
  • HRB is used up to a hardness value of 100, which is equivalent to HRC 22.
  • the amount of Cu, Mo, and N in each Example/Heat is also shown for ease of comparison.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

Alliage d'acier inoxydable austénitique possédant la composition suivante en pourcentages en poids: C 0,025-0,15; Mn 4-12; Si 1,0 max.; P 0,2 max.; S 0,1 max.; Cr 15,5-17,5; Ni 1-4; Mo 0,25-1,5; Cu 1,5-4; 1,0 max.; Co 1,0 max.; N 0,05-0,30. Le reste de l'alliage est composé de fer et des impuretés usuelles. Dans les plages précitées, les éléments sont équilibrés de sorte que la quantité combinée de carbone et d'azote est d'au moins 0,19 % environ, la quantité combinée de chrome et de molybdène est inférieure à 17,75 % et %Cr+3,3(%Mo)+13(%N)⊃20,5. Cet alliage combine les propriétés de résistance à la corrosion, de capacité de formage et de résistance au durcissement.
EP99958707A 1998-11-02 1999-10-29 Acier inoxydable austenitique cr-mn-ni-cu Withdrawn EP1131472A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US10660698P 1998-11-02 1998-11-02
US106606P 1998-11-02
PCT/US1999/025478 WO2000026428A1 (fr) 1998-11-02 1999-10-29 Acier inoxydable austenitique cr-mn-ni-cu

Publications (1)

Publication Number Publication Date
EP1131472A1 true EP1131472A1 (fr) 2001-09-12

Family

ID=22312320

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99958707A Withdrawn EP1131472A1 (fr) 1998-11-02 1999-10-29 Acier inoxydable austenitique cr-mn-ni-cu

Country Status (4)

Country Link
EP (1) EP1131472A1 (fr)
KR (1) KR20010083939A (fr)
CA (1) CA2348909A1 (fr)
WO (1) WO2000026428A1 (fr)

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7235212B2 (en) 2001-02-09 2007-06-26 Ques Tek Innovations, Llc Nanocarbide precipitation strengthened ultrahigh strength, corrosion resistant, structural steels and method of making said steels
EP1624082A1 (fr) * 2004-05-25 2006-02-08 Edelstahl Witten-Krefeld GmbH Acier austénitique non-magnétisable et utilisations de cet acier.
EP1690957A1 (fr) * 2005-02-14 2006-08-16 Rodacciai S.p.A. Acier inoxidable austénitique
KR100894679B1 (ko) * 2007-06-19 2009-04-24 한양대학교 산학협력단 오스테나이트 내침식 철계 합금
AU2015223307B2 (en) * 2007-11-29 2016-06-16 Ati Properties, Inc Lean austenitic stainless steel
EP2220261B1 (fr) * 2007-11-29 2018-12-26 ATI Properties LLC Acier inoxydable austénitique pauvre
AU2013200660B2 (en) * 2007-11-29 2015-09-17 Ati Properties, Inc. Lean austenitic stainless steel
AU2008341063C1 (en) 2007-12-20 2014-05-22 Ati Properties, Inc. Austenitic stainless steel low in nickel containing stabilizing elements
CN101903549B (zh) 2007-12-20 2013-05-08 Ati资产公司 耐腐蚀的低组分奥氏体不锈钢
US8337749B2 (en) 2007-12-20 2012-12-25 Ati Properties, Inc. Lean austenitic stainless steel
KR101014515B1 (ko) * 2008-12-05 2011-02-14 현대자동차주식회사 이단 테이크업 장치
SE533635C2 (sv) 2009-01-30 2010-11-16 Sandvik Intellectual Property Austenitisk rostfri stållegering med låg nickelhalt, samt artikel därav
KR102160735B1 (ko) * 2018-08-13 2020-09-28 주식회사 포스코 강도가 향상된 오스테나이트계 스테인리스강
CN114941107B (zh) * 2022-05-31 2023-09-29 哈尔滨汽轮机厂有限责任公司 630℃超超临界汽轮机叶片用奥氏体不锈钢材料的制备方法

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BE754371A (fr) * 1970-01-13 1971-01-18 Nisshin Steel Co Ltd Aciers inoxydables austenitiques
SE453998B (sv) * 1980-05-05 1988-03-21 Armco Inc Austenitiskt rostfritt stal
JPH06306544A (ja) * 1993-04-22 1994-11-01 Nippon Steel Corp 高強度・非磁性の高耐銹性快削ステンレス鋼線材
EP0694626A1 (fr) * 1994-07-26 1996-01-31 Acerinox S.A. Acier inoxydable austénitique à basse teneur en nickel

Non-Patent Citations (1)

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Title
See references of WO0026428A1 *

Also Published As

Publication number Publication date
WO2000026428A1 (fr) 2000-05-11
CA2348909A1 (fr) 2000-05-11
KR20010083939A (ko) 2001-09-03

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