Iron-based sintered alloy and method for producing the same

Patent metadata

Field	Value
Publication number	US-2016376687-A1
Application number	US-201615190643-A
Country	US
Kind code	A1
Filing date	Jun 23, 2016
Priority date	Jun 24, 2015
Publication date	Dec 29, 2016
Grant date	—

Abstract

A method for producing an iron-based sintered alloy, which is used in sliding components in pairs and has a composition including, in terms of percent by mass, Ti: 18.4 to 24.6%, Mo: 2.8 to 6.6%, C: 4.7 to 7.0%, Cr: 7.5 to 10.0%, Ni: 4.5 to 6.5%, Co: 1.5 to 4.5%, Al: 0.6 to 1.0%, the balance being Fe and unavoidable impurities, wherein the method is carried out such that the alloy has a structure in which hard particles are dispersed in an island form in a matrix and, while an area ratio thereof is kept constant, a maximum circle equivalent diameter thereof is controlled to a predetermined value of 40 to 10 μm.

First claim

What is claimed is:

1 . A method for producing an iron-based sintered alloy that is used in sliding components in pairs, the iron-based sintered alloy having a composition comprising, in terms of percent by mass, Ti: 18.4 to 24.6%, Mo: 2.8 to 6.6%, C: 4.7 to 7.0%, Cr: 7.5 to 10.0%, Ni: 4.5 to 6.5%, Co: 1.5 to 4.5%, Al: 0.6 to 1.0%, the balance being Fe and unavoidable impurities,
wherein the alloy has a structure in which hard particles are dispersed in an island shape in a matrix and, wherein the method comprises, while an area ratio of the hard particles is kept constant, controlling a maximum circle equivalent diameter of the hard particles to a predetermined value of 40 to 10 μm.

2 . The method for producing an iron-based sintered alloy according to claim 1 , wherein the area ratio of the hard particles is 38% to 41% and standard deviation of the area ratio of the hard particles is 2.5 to 3.5.

3 . The method for producing an iron-based sintered alloy according to claim 1 , wherein Ti, Mo, and C forming the hard particles are supplied as a TiC powder and a Mo powder.

4 . The method for producing an iron-based sintered alloy according to claim 1 , wherein the hard particles are formed from a carbide consisting of a TiC powder and a metal powder including a Mo metal powder.

5 . The method for producing an iron-based sintered alloy according to claim 1 , wherein the components used in pairs are components to be used as a die and a cutter blade.

6 . An iron-based sintered alloy which is used in a die and a cutter blade for a pelletizer of a resin extruder, the iron-based sintered alloy having a composition comprising, in terms of percent by mass, Ti: 18.4 to 24.6%, Mo: 2.8 to 6.6%, C: 4.7 to 7.0%, Cr: 7.5 to 10.0%, Ni: 4.5 to 6.5%, Co: 1.5 to 4.5%, Al: 0.6 to 1.0%, the balance being Fe and unavoidable impurities, and the iron-based sintered alloy having a structure in which hard particles are dispersed in an island shape in a matrix,
wherein a coefficient of friction after passing through a conforming stage is 0.12 or less in a friction test in water by a cutter blade-on-disk method simulating a die and a cutter blade.

7 . An iron-based sintered alloy that is used in sliding components in pairs, the iron-based sintered alloy having a composition comprising, in terms of percent by mass, Ti: 18.4 to 24.6%, Mo: 2.8 to 6.6%, C: 4.7 to 7.0%, Cr: 7.5 to 10.0%, Ni: 4.5 to 6.5%, Co: 1.5 to 4.5%, Al: 0.6 to 1.0%, the balance being Fe and unavoidable impurities,
wherein the alloy has a structure in which hard particles are dispersed in an island shape in a matrix, an area ratio of the hard particles is within a constant range and a maximum circle equivalent diameter of the hard particles is a predetermined value of 40 μm to 10 μm.

8 . The iron-based sintered alloy according to claim 7 , wherein the area ratio of the hard particles is 38% to 41% and standard deviation of the area ratio of the hard particles is 2.5 to 3.5.

9 . The iron-based sintered alloy according to claim 7 , wherein the hard particles are formed from a titanium carbide, a Mo carbide or a composite carbide of titanium and molybdenum.

10 . The iron-based sintered alloy according to claim 7 , wherein the components used in pairs are components to be used as a die and a cutter blade.

11 . The iron-based sintered alloy according to claim 7 ,
wherein a coefficient of friction after passing through a conforming stage is 0.12 or less in a friction test in water by a cutter blade-on-disk method simulating a die and a cutter blade.

12 . The iron-based sintered alloy according to claim 7 , wherein standard deviation of the maximum circle equivalent diameter is 6 μm to 4 μm.

13 . A method for producing the iron-based sintered alloy according to claim 7 , the method comprising:
forming a compact by mixing material powders including TiC, Mo, Ni, Cr, Co, Al and Fe and subjecting the mixture by a cold isostatic pressing method; and subjecting the formed compact to a vacuum sintering, a solution treatment and an aging treatment.

14 . The method for producing the iron-based sintered alloy according to claim 13 , wherein the vacuum sintering comprises heating the formed compact under vacuum at a sintering temperature of 1,380° C. to 1,400° C.

Assignees

• Japan Steel Works Ltd

Inventors

• Watanabe Yusuke
• Kusada Kakeru
• Makida Tetsuo
• Sawamura Youhei

Classifications

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• C22C38/50

  with titanium or zirconium · CPC title

• B22F2003/248

  Thermal after-treatment · CPC title

• C22C38/52

  with cobalt · CPC title

• C22C38/14 Primary

  containing titanium or zirconium · CPC title