US3810756A - Method of making valve seat rings from a mixture of c,pb and a pre-alloy of fe-co-ni-mo by powder metallurgy - Google Patents

Method of making valve seat rings from a mixture of c,pb and a pre-alloy of fe-co-ni-mo by powder metallurgy Download PDF

Info

Publication number
US3810756A
US3810756A US00237504A US23750472A US3810756A US 3810756 A US3810756 A US 3810756A US 00237504 A US00237504 A US 00237504A US 23750472 A US23750472 A US 23750472A US 3810756 A US3810756 A US 3810756A
Authority
US
United States
Prior art keywords
mixture
valve seat
cobalt
alloy
rings
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.)
Expired - Lifetime
Application number
US00237504A
Inventor
M Koehler
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Application granted granted Critical
Publication of US3810756A publication Critical patent/US3810756A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0207—Using a mixture of prealloyed powders or a master alloy
    • 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%

Definitions

  • the present invention relates to a method of making valve seat rings by a powder metallurgical method, according to which an iron powder having added thereto carbon and lead, and other alloying constituents is briquetted, sintered, and subjected to a post treatment.
  • This post treatment may consist either in a hot compression or in a cold compression at a pressure which exceeds the briquetting pressure.
  • the heat compression or cold compression may be followed by a heat treatment according to which the workpiece is briefly heated to a temperature above the AC3-point whereupon it is quickly cooled and annealed at temperatures up to 650 C. If desired, prior to the cold compression, an additional heat treatment may be carried out.
  • a sliding and wear-resistant material for cylinder bushings and valve rings has become known which is produced according to the above mentioned method, and which for purposes of increasing its strength also contains from 1 to 4% lead, and nickel in quantities of from 0.5 to 5%, in addition to iron and carbon, which in the finished product is contained in quantities of from 0.5 to 1%.
  • valve seat rings For certain uses, for instance, when making valve seat rings for outlet rings of motor vehicles, it is necessary that the material in addition to the above mentioned strength properties also has an increased heat resistance which means it has suflicient heat resistance at temperatures up to 650 C.
  • valve seat rings with increased heat resistance have been disclosed in US. Pat. 3,471,343, which are made of a pulverous mixture which prior to the above described treatment has the following composition:
  • the individual powders are mixed and are then briquetted at a pressure of approximately 3.5 tons per square centimeter and are subsequently at a temperature of approximately 1100" C. sintered in a neutral atmosphere for approximately three hours.
  • the sintered workpieces are then cooled and are subjected to a cold compression at a pressure of approximately 12 tons per square centimeter, are heated for fifteen minutes to a temperature above the AC3-point, and then quickly cooled, and are annealed at a temperature of 580 C. for a period of thirty minutes.
  • the Brinell hardness of the material is approximately 320 kilograms per square millimeter at room temperature and 205 kilograms per square millimeter at a temperature of 600 C.
  • Valve seat rings made in conformity with this method thus have an increased heat resistance and can be used as outlet valves for motor vehicles. Practical tests of these rings which have proved very satisfactory, and which tests have been carried out on the test stand under full load have shown a useful running period of 250 hours.
  • the present invention consists primarily in that as starting mixture there is employed a pulverized pre-alloy which contains from 1 to 2% of nickel, from 1 to 2% of molybdenum, from 6 to 7% of cobalt, and the remainder iron, while the prealloyed steel powder has added thereto carbon in a quantity of from 0.5 to 1%, and lead in a quantity of from 0.7 to 1%, whereupon said mixture is, in a manner known per se, briquetted, sintered, cold or hot post compressed, and, if desired, is annealed.
  • the present invention furthermore provides that the pre-alloy from which the starting powder is made will, in addition to the above mentioned alloy components, also contain chromium in a quantity of from 1 to 2%, and titanium in a quantity of from 0.3 to 0.5%.
  • valve seat rings made according to the method of the present invention have proved that the employment of a prealloy instead of individual powders of the alloys components will yield rings which have a considerably improved running behavior with regard to heat resistance, corrosion resistance, and erosion resistance. Furthermore, a considerable increase in the heat withdrawal or heat deduction was ascertained. Whereas with running tests under full load, the heretofore known valve seat rings made with a powder mixture containing 12% cobalt failed after a running period of approximately 25 0 hours, which is rather high, motors equipped with valve seat rings according to the present invention have run still highly satisfactorily after a running period of 500 hours. This result was ascertained not only when employing lead-containing fuel, but also when employing lead-free fuel. This fact is of particular importance, because lead-free fuels are and will be employed more and more, in view of the ecology and the heretofore insert cast rings have an unsatisfactory life span when employing lead-free fuel.
  • the sintered rings After the sintered rings had cooled, they were post compressed at a pressure of 12 tons per square centimeter and were heated for fifteen minutes to a temperature above the AC3-point and thereupon were quickly cooled. Subsequently, the rings were annealed for thirty minutes at a temperature of 650 C.
  • valve seat rings which in customary manner were produced from a powder mixture with a cobalt content of 12%.
  • a powder metallurgical method of making high heat resistant valve seat including the steps of providing a starting mixture of metal powders, briquetting, sintering and post-compressing said mixture, the improvement comprising: providing as said starting mixture, a mixture comprising 0.5 to 1.0% carbon, 0.7 to 1.5% lead and the remainder a pulverized prealloy consisting essentially of from 1.0 to 2.0% of nickel, from 1.0 to 2.0% of molybdenum, from 6.0 to 7.0% of cobalt and the remainder iron.
  • the method according to claim 1 which includes the step of when preparing the starting mixture also adding thereto a quantity of from 1 to 2% of chromium and a quantity off rom 0.3 to 0.5% of titanium.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)

Abstract

A POWDER METALLURGICAL METHOD OF MAKING VALVE SEAT RINGS HAVING A HIGH HEAT RESISTANCE, WHILE EMPLOYING A METAL POWDER WHICH IN ADDITION TO IRON CONTAINS FROM 0.5 TO 1% OF CARBON, FROM 0.7 TO 1.5% OF LEAD, FROM 1 TO 2% OF NICKEL, FROM 1.0 TO 2.0% OF MULYBDENUM, AND COBALT. AS STARTING MIXTURE IS EMPOLYED A PULVERIZED PRE-ALLOY WHICH CONTAINS FROM 1 TO 2% OF NICKEL, 1.0 TO 2% OF MOLYBDENUM, FROM 6.0 TO 7.0% OF COBALT, AND THE REMAINDER IRON. TO THE TUUS PRE-ALLOYED STEEL POWDER THERE IS ADDED CARBON IN QUANTITIES OF FROM 0.5 TO 1.0%, AND LEAD AT A QUANTITY OF FROM 0.7 TO 1.5%.SUBEEQUENTLY, THE MIXTURE IS BRIQUETTED, SINTERED COLD OR HOT POST-COMPRESSED, AND IF DESIRED, IS ANNEALED.

Description

United States Patent Office 3,810,756 Patented May 14, 1974 METHOD OF MAKING VALVE SEAT RINGS FROM A MIXTURE OF C, Pb AND A PRE-ALLOY F Fe-Co-Ni-Mo BY POWDER METALLURGY Max Koehler, deceased, by Michael Koehler, Osterfeldstrasse 51, 5802 Wetter muhr) 4-Wengern, Federal Republic of Germany No Drawing. Filed Mar. 23, 1972, Ser. No. 237,504 Claims priority, application Germany, Mar. 24, 1971,
P 21 14 160.6 Int. Cl. 1322f 3/16, /00
US. Cl. 75-214 5 Claims ABSTRACT OF THE DISCLOSURE A powder metallurgical method of making valve seat rings having a high heat resistance, while employing a metal powder which in addition to iron contains from 0.5 to 1% of carbon, from 0.7 to 1.5% of lead, from 1 to 2% of nickel, from 1.0 to 2.0% of molybdenum, and cobalt. As starting mixture is employed a pulverized pre-alloy which contains from 1 to 2% of nickel, 1.0 to 2% of molybdenum, from 6.0 to 7.0% of cobalt, and the remainder iron. To the thus pre-alloyed steel powder there is added carbon in quantities of from 0.5 to 1.0%, and lead at a quantity of from 0.7 to 1.5 Subsequently, the mixture is briquetted, sintered, cold or hot post-compressed, and if desired, is annealed.
The present invention relates to a method of making valve seat rings by a powder metallurgical method, according to which an iron powder having added thereto carbon and lead, and other alloying constituents is briquetted, sintered, and subjected to a post treatment. This post treatment may consist either in a hot compression or in a cold compression at a pressure which exceeds the briquetting pressure. The heat compression or cold compression may be followed by a heat treatment according to which the workpiece is briefly heated to a temperature above the AC3-point whereupon it is quickly cooled and annealed at temperatures up to 650 C. If desired, prior to the cold compression, an additional heat treatment may be carried out.
A sliding and wear-resistant material for cylinder bushings and valve rings has become known which is produced according to the above mentioned method, and which for purposes of increasing its strength also contains from 1 to 4% lead, and nickel in quantities of from 0.5 to 5%, in addition to iron and carbon, which in the finished product is contained in quantities of from 0.5 to 1%.
For certain uses, for instance, when making valve seat rings for outlet rings of motor vehicles, it is necessary that the material in addition to the above mentioned strength properties also has an increased heat resistance which means it has suflicient heat resistance at temperatures up to 650 C. For outlet valves of motor vehicles, valve seat rings with increased heat resistance have been disclosed in US. Pat. 3,471,343, which are made of a pulverous mixture which prior to the above described treatment has the following composition:
from 0.8 to 1.5% from 1.0 to 4.0% from 0.5 to 5.0% of nickel,
from 1.2 to 1.8% of molybdenum, from 9.6 to 14.4% of cobalt,
and the remainder iron.
of graphite, of lead,
powder. The individual powders are mixed and are then briquetted at a pressure of approximately 3.5 tons per square centimeter and are subsequently at a temperature of approximately 1100" C. sintered in a neutral atmosphere for approximately three hours. The sintered workpieces are then cooled and are subjected to a cold compression at a pressure of approximately 12 tons per square centimeter, are heated for fifteen minutes to a temperature above the AC3-point, and then quickly cooled, and are annealed at a temperature of 580 C. for a period of thirty minutes. The Brinell hardness of the material is approximately 320 kilograms per square millimeter at room temperature and 205 kilograms per square millimeter at a temperature of 600 C. Valve seat rings made in conformity with this method thus have an increased heat resistance and can be used as outlet valves for motor vehicles. Practical tests of these rings which have proved very satisfactory, and which tests have been carried out on the test stand under full load have shown a useful running period of 250 hours.
It is an object of the present invention to improve the properties of the heretofore known valve seat rings having an increased heat resistance, in other words, to improve heretofore known valve seat rings containing nickel, molybdenum and cobalt, so that they will have an increased corrosion and erosion resistance and will also show an improved running behavior.
These and other objects and advantages of the invention will appear more clearly from the following specification and example. It has been found, surprisingly, that the above objects can be realized when the aforementioned alloy components are added to the starting mixture, not individually in the form of a powder, but when as starting mixture a pulverized pre-alloy is employed, which means a steel powder which contains the alloying components or ingredients.
With a method for making valve seat rings with increased heat resistance by a powder metallurgical method while employing a metal powder which, in addition to iron and carbon contains lead, nickel, molybdenum, and cobalt, the present invention consists primarily in that as starting mixture there is employed a pulverized pre-alloy which contains from 1 to 2% of nickel, from 1 to 2% of molybdenum, from 6 to 7% of cobalt, and the remainder iron, while the prealloyed steel powder has added thereto carbon in a quantity of from 0.5 to 1%, and lead in a quantity of from 0.7 to 1%, whereupon said mixture is, in a manner known per se, briquetted, sintered, cold or hot post compressed, and, if desired, is annealed.
The present invention furthermore provides that the pre-alloy from which the starting powder is made will, in addition to the above mentioned alloy components, also contain chromium in a quantity of from 1 to 2%, and titanium in a quantity of from 0.3 to 0.5%.
Tests with valve seat rings made according to the method of the present invention have proved that the employment of a prealloy instead of individual powders of the alloys components will yield rings which have a considerably improved running behavior with regard to heat resistance, corrosion resistance, and erosion resistance. Furthermore, a considerable increase in the heat withdrawal or heat deduction was ascertained. Whereas with running tests under full load, the heretofore known valve seat rings made with a powder mixture containing 12% cobalt failed after a running period of approximately 25 0 hours, which is rather high, motors equipped with valve seat rings according to the present invention have run still highly satisfactorily after a running period of 500 hours. This result was ascertained not only when employing lead-containing fuel, but also when employing lead-free fuel. This fact is of particular importance, because lead-free fuels are and will be employed more and more, in view of the ecology and the heretofore insert cast rings have an unsatisfactory life span when employing lead-free fuel.
It has furthermore been ascertained that when employing prealloys with a quantity of 12% cobalt, heretofore considered necessary, no improvement of the properties was obtained relative to rings which in conformity with the invention were produced with prealloys having a conten of from 6 to 7% cobalt. A reduction in the cobalt contents from 12% to a content of from 6 to 7% cobalt with heretofore known valve rings will, however, change the properties of such rings to such an extent that they could no longer be used for high load engines. This result is surprising and brings about that valve seat rings according to the invention with a content of only from 6 to 7% of cobalt can be used, where heretofore only rings with 10% cobalt of non-prealloyed powder could be used. The employment of prealloyed steel powder with a considerably lower cobalt content furthermore brings about a more uniform description of the individual alloying components and also results in a better diffusion of the carbon and therefore in an increase in the conductivity and in an improved corrosion and erosion resistance.
The present invention will now be described in connection with an example.
EXAMPLE As starting material for making valve seat rings there was employed a pulverized pre-alloy having the following composition:
With this prealloyed steel powder there were intermixed 0.8% of carbon and 1.2% of lead. The thus obtained mixture was then pressed into rings at a pressure of 3.5 tons per square centimeter. The thus obtained product was then sintered in a neutral atmosphere at a temperature of 1100 C. over a period of approximately three hours.
After the sintered rings had cooled, they were post compressed at a pressure of 12 tons per square centimeter and were heated for fifteen minutes to a temperature above the AC3-point and thereupon were quickly cooled. Subsequently, the rings were annealed for thirty minutes at a temperature of 650 C.
The thus produced rings showed an unexpected improvement with regard to corrosion, erosion, and heat resistance over valve seat rings which in customary manner were produced from a powder mixture with a cobalt content of 12%.
When employed in engines, an excellent running behavior was observed. After a running period of 500 hours under full load, the rings were still satisfactorily running even when employing lead-free fuel.
It is, of course, to be understood that the present invention is, by no means, limited to the specific example set forth hereinbefore, but also comprises any modifications within the scope of the appended claims.
What is claimed is:
1. In a powder metallurgical method of making high heat resistant valve seat n'ngs including the steps of providing a starting mixture of metal powders, briquetting, sintering and post-compressing said mixture, the improvement comprising: providing as said starting mixture, a mixture comprising 0.5 to 1.0% carbon, 0.7 to 1.5% lead and the remainder a pulverized prealloy consisting essentially of from 1.0 to 2.0% of nickel, from 1.0 to 2.0% of molybdenum, from 6.0 to 7.0% of cobalt and the remainder iron.
2. The method according to claim 1, wherein the sintered mixture is cold post-compressed.
3. The method according to claim 1, wherein the sintered mixture is hot post-compressed.
4. The method according to claim 1, which includes the step of heat treating the post-compressed sintered material.
5. The method according to claim 1, which includes the step of when preparing the starting mixture also adding thereto a quantity of from 1 to 2% of chromium and a quantity off rom 0.3 to 0.5% of titanium.
References Cited UNITED STATES PATENTS 3,471,343 10/1964 Koehler 29l82 X 2,381,023 8/1945 Wulif -213 X 2,368,282 l/l945 Wulff 75-213 X 2,352,316 6/1944 Goetzel 752l3 X CARL D. QUARFORTH, Primary Examiner R. S. SCHAFER, Assistant Examiner U.S. Cl. X.R.
US00237504A 1971-03-24 1972-03-23 Method of making valve seat rings from a mixture of c,pb and a pre-alloy of fe-co-ni-mo by powder metallurgy Expired - Lifetime US3810756A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19712114160 DE2114160B2 (en) 1971-03-24 1971-03-24 PROCESS FOR MANUFACTURING VALVE SEATING RINGSX BY POWDER METALLURGICAL WAYS

Publications (1)

Publication Number Publication Date
US3810756A true US3810756A (en) 1974-05-14

Family

ID=5802556

Family Applications (1)

Application Number Title Priority Date Filing Date
US00237504A Expired - Lifetime US3810756A (en) 1971-03-24 1972-03-23 Method of making valve seat rings from a mixture of c,pb and a pre-alloy of fe-co-ni-mo by powder metallurgy

Country Status (11)

Country Link
US (1) US3810756A (en)
AT (1) AT324382B (en)
BE (1) BE780761A (en)
CA (1) CA966703A (en)
CH (1) CH549427A (en)
DE (1) DE2114160B2 (en)
FR (1) FR2130489B1 (en)
GB (1) GB1338182A (en)
IT (1) IT952193B (en)
LU (1) LU65022A1 (en)
SE (1) SE384040B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51110119A (en) * 1975-03-25 1976-09-29 Nissan Motor NAINENKIKANNOBENZA
US4002471A (en) * 1973-09-24 1977-01-11 Federal-Mogul Corporation Method of making a through-hardened scale-free forged powdered metal article without heat treatment after forging
US4077108A (en) * 1975-03-21 1978-03-07 Ugine Aciers Process for producing dense machinable alloys from particulate scrap
US4098607A (en) * 1976-11-04 1978-07-04 The United States Of America As Represented By The Secretary Of The Army 18% Ni-Mo-Co maraging steel having improved toughness and its method of manufacture
US5489324A (en) * 1992-11-27 1996-02-06 Toyota Jidosha Kabushiki Kaisha Fe-based sintered alloy having wear resistance
US20080025863A1 (en) * 2006-07-27 2008-01-31 Salvator Nigarura High carbon surface densified sintered steel products and method of production therefor
CN102672186A (en) * 2012-06-07 2012-09-19 太仓市锦立得粉末冶金有限公司 Manufacturing process for gear ring in powder metallurgy
CN102672179A (en) * 2012-06-07 2012-09-19 太仓市锦立得粉末冶金有限公司 Production technique of powder metallurgy product

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5346768B2 (en) * 1973-01-11 1978-12-16
US4422875A (en) * 1980-04-25 1983-12-27 Hitachi Powdered Metals Co., Ltd. Ferro-sintered alloys

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB553297A (en) * 1939-12-09 1943-05-17 Standard Oil Dev Co An improved process for the production of beta olefins from alpha olefins and from mixtures containing alpha olefins
FR1478137A (en) * 1965-05-07 1967-04-21 Material with good sliding characteristics

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4002471A (en) * 1973-09-24 1977-01-11 Federal-Mogul Corporation Method of making a through-hardened scale-free forged powdered metal article without heat treatment after forging
US4077108A (en) * 1975-03-21 1978-03-07 Ugine Aciers Process for producing dense machinable alloys from particulate scrap
JPS51110119A (en) * 1975-03-25 1976-09-29 Nissan Motor NAINENKIKANNOBENZA
JPS5536242B2 (en) * 1975-03-25 1980-09-19
US4098607A (en) * 1976-11-04 1978-07-04 The United States Of America As Represented By The Secretary Of The Army 18% Ni-Mo-Co maraging steel having improved toughness and its method of manufacture
US5489324A (en) * 1992-11-27 1996-02-06 Toyota Jidosha Kabushiki Kaisha Fe-based sintered alloy having wear resistance
US5503654A (en) * 1992-11-27 1996-04-02 Toyota Jidosha Kabushiki Kaisha Fe-based alloy powder and adapted for sintering, Fe-based sintered alloy having wear resistance, and process for producing the same
US5512080A (en) * 1992-11-27 1996-04-30 Toyota Jidosha Kabushiki Kaisha Fe-based alloy powder adapted for sintering, Fe-based sintered alloy having wear resistance, and process for producing the same
US20080025863A1 (en) * 2006-07-27 2008-01-31 Salvator Nigarura High carbon surface densified sintered steel products and method of production therefor
US7722803B2 (en) 2006-07-27 2010-05-25 Pmg Indiana Corp. High carbon surface densified sintered steel products and method of production therefor
CN102672186A (en) * 2012-06-07 2012-09-19 太仓市锦立得粉末冶金有限公司 Manufacturing process for gear ring in powder metallurgy
CN102672179A (en) * 2012-06-07 2012-09-19 太仓市锦立得粉末冶金有限公司 Production technique of powder metallurgy product

Also Published As

Publication number Publication date
BE780761A (en) 1972-07-17
FR2130489B1 (en) 1976-08-06
SE384040B (en) 1976-04-12
CH549427A (en) 1974-05-31
AT324382B (en) 1975-08-25
FR2130489A1 (en) 1972-11-03
DE2114160B2 (en) 1972-03-16
GB1338182A (en) 1973-11-21
LU65022A1 (en) 1972-07-11
DE2114160A1 (en) 1972-03-16
CA966703A (en) 1975-04-29
IT952193B (en) 1973-07-20

Similar Documents

Publication Publication Date Title
EP0331679B1 (en) High density sintered ferrous alloys
US4970049A (en) Sintered materials
JP2687125B2 (en) Sintered metal compact used for engine valve parts and its manufacturing method.
US5859376A (en) Iron base sintered alloy with hard particle dispersion and method for producing same
US5552109A (en) Hi-density sintered alloy and spheroidization method for pre-alloyed powders
US3810756A (en) Method of making valve seat rings from a mixture of c,pb and a pre-alloy of fe-co-ni-mo by powder metallurgy
US3744993A (en) Powder metallurgy process
US3889350A (en) Method of producing a forged article from prealloyed water-atomized ferrous alloy powder
US3471343A (en) Process for the production of sinter iron materials
US3461069A (en) Self-lubricating bearing compositions
US3183127A (en) Heat treatable tool steel of high carbide content
US3694173A (en) Ferrous alloys
US5069867A (en) Process of manufacturing high-strength sintered members
US4049429A (en) Ferritic alloys of low flow stress for P/M forgings
US3809540A (en) Sintered steel bonded titanium carbide tool steel characterized by an improved combination of transverse rupture strength and resistance to thermal shock
US2881511A (en) Highly wear-resistant sintered powdered metal
US2284638A (en) Metallurgy of ferrous metals
US4018632A (en) Machinable powder metal parts
US3715792A (en) Powder metallurgy sintered corrosion and wear resistant high chromium refractory carbide alloy
JPH08501832A (en) Method of producing sintered alloy steel components
US2741827A (en) Process for the manufacture of piston rings by powder metallurgy and articles obtained thereby
US4198234A (en) Sintered metal articles
US2882190A (en) Method of forming a sintered powdered metal piston ring
US2884687A (en) Wear-resistant sintered powdered metal
US2156802A (en) Method of making lead alloys