High impact strength power metal part and method for making same
AssigneeSCM Metal Products, Inc.
InventorsMark Svilar, Erhard Klar
Life of this patent
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Abstract
A copper or copper alloy infiltrated ferrous powder metal part, and method for making the same, characterized as having after infiltration an overall density of at least 7.50 g/cm.sup.3 and a diffusion depth of copper into the steel matrix of less than about 4 micrometers as determined by chemical etching or less than about 8 micrometers as determined by electron dispersive X-ray analysis (EDXA), wherein said ferrous metal is plain carbon steel having a combined carbon content in the range of about 0.15% to about 1.25%, or a low alloy steel.
Claims38
A copper infiltrated ferrous powder metal part infiltrated with copper or a copper alloy characterized as having after infiltration an overall density of at least 7.50 g/cm.sup.3 and a diffusion depth of copper into the steel matrix of less than about 4 micrometers as determined by chemical etching or less than about 8 micrometers as determined by electron dispersive X-ray analysis, wherein said ferrous metal is plain carbon steel having a combined carbon content in the range of about 0.15% to about 1.25%.
A process for infiltrating ferrous powder metal parts with a copper or copper alloy infiltrant to yield an impact strength as measured by the unnotched Charpy test, of greater than 50 ft. lbs., and an ultimate tensile strength of greater than 60 ksi, comprising the steps of:
- (a) pressing a ferrous powder metal to a density of at least about 80% of theoretical density;
- (b) sintering said powder metal;
- and
- (c) infiltrating said powder metal with a copper or copper alloy infiltrant assuring that the depth of copper diffusion into the steel matrix as measured by chemical etching is less than about 4 micrometers, or less than about 8 micrometers when determined by electron dispersive X-ray analysis, wherein said ferrous metal is plain carbon steel having a combined carbon content in the range of about 0.15% to about 1.25%.
A copper infiltrated ferrous powder metal part infiltrated with copper or a copper alloy characterized as having after infiltration an overall density of at least 7.50 g/cm.sup.3 and a diffusion depth of copper into the steel matrix of less than about 4 micrometers as determined by chemical etching or less than about 8 micrometers as determined by electron dispersive X-ray analysis, wherein said ferrous metal is a low alloy or tool steel.
A process for infiltrating ferrous powder metal parts with a copper or copper alloy infiltrant to yield an impact strength as measured by the unnotched Charpy test, of greater than 50 ft. lbs., and an ultimate tensile strength of greater than 60 ksi, comprising the steps of:
- (a) pressing a ferrous powder metal to a density of at least about 80% of theoretical density;
- (b) sintering said powder metal;
- and
- (c) infiltrating said powder metal with a copper or copper alloy infiltrant assuring that the depth of copper diffusion into the steel matrix as measured by chemical etching is less than about 4 micrometers, or less than about 8 micrometers when determined by electron dispersive X-ray analysis, wherein said ferrous metal is a low alloy or tool steel.
A process for infiltrating ferrous powder metal parts witha copper or copper alloy infiltrant to yield an impact strength, as measured by the unnotched Charpy test, of greater than 50 foot pounds, and an ultimate tensile strength of greater than 46 ksi in the as-infiltrated condition, comprising the steps of:
- (a) filling a die with ferrous powder metal to achieve uniform powder metal distribution in said die;
- (b) pressing said ferrous powder metal to a density of at least about 80% of theoretical density;
- (c) sintering said ferrous powder metal under an atmosphere of an inert gas or a reducing gas using conditions effective for sintering;
- (d) infiltrating said ferrous powder metal with a copper or copper alloy infiltrant under an atmosphere of an inert gas with or without a reducing gas and assuring that th edepth of copper diffusion into the steel matrix as measured by chemical etching is less than about 4 micrometers, or less than about 8 micrometers when determined by electron dispersive X-ray analysis;
- (e) the filling, pressing, sintering and infiltrating conditions being effective to provide a powder metal part having a residual uninfiltrated porosity and a maximum pore size of residual uninfiltrated porosity, as taken from a worst field of view in a functionally critical area of said metal part, of less than about 7 volume percent and 125 micrometers, respectively;
- said ferrous powder metal following infiltration having a combined carbon content in the range of about 0.15% to about 1.25%.
A copper infiltrated ferrous powder metal part prepared by the steps of:
- (a) filling a die with ferrous powder metal to achieve uniform powder metal distributionin said die;
- (b) pressing said powder metal to a density of at least about 80% of theoretical density;
- (c) sintering said powder metal under an inert or reducing gas atmosphere using conditions effective for sintering;
- and
- (d) infiltrating said powder metal also under an inert or reducing gas atmosphere using conditions effective for infiltrating, with a copper or copper alloy infiltrant assuring that the depth of copper diffusion into the steel matrix as measured by chemical etching is less than about 4 micrometers, or less than about 8 micrometers when determined by electron dispersive X-ray analysis.
A process for infiltrating ferrous powder metal parts with a copper or copper alloy infiltrant to yield an impact strength, as measured by the unnotched Charpy test, of greater than 50 foot pounds, and an ultimate tensile strength of greater than 46 ksi, in the as-infiltrated condition, comprising the steps of:
- (a) filling a die with ferrous powder metal to achieve uniform powder metal distribution in said die;
- (b) pressing said ferrous powder metal to a density of at least about 80% of theoretical density;
- (c) sintering sid ferrous powder metal under an inert gas atmosphere at ambient pressure using sintering conditions;
- (d) infiltrating said ferrous powder metal with a copper or copper alloy infiltrant under an inert gas atmosphere at ambient pressure using infiltrating conditions;
- (e) the filling, pressing, sintering and infiltrating conditions being effective to provide a powder metal part having a residual uninfiltrated porosity and a maximum pore size of residual uninfiltrated porosity, as taken from a worst field of view in a functionally critical area of said metal part, of less than about 7 volume percent and 125 micrometers, respectively;
- said ferrous powder metal following infiltration having a combined carbon content in the range of about 0.15% to about 1.25%.
Dependencies are inferred from the claim text.