Selective case hardening processes at low temperature
First Claim
1. An article comprising:
- a body comprising a metal alloy;
a first portion of said body having a first hardness characteristic; and
a second portion of said body having a second hardness characteristic;
said second portion being less than the entire body and comprising a carburized surface area substantially free of carbides.
2 Assignments
0 Petitions
Accused Products
Abstract
A selectively case hardened steel article by low temperature carburization includes a body made of a chromium bearing nickel or ferrous based alloy (for example, stainless steel), a first portion of the body having a first hardness characteristic, and a second portion of the body having a second hardness characteristic; the second portion being less than the entire body and substantially free of carbides. One method for selective case hardening by low temperature carburization includes the steps of applying a carbon blocking mask over surface areas of the article that are not going to be carburized; activating those surface areas that are to be carburized; diffusing carbon into the activated surface areas at a temperature below which carbides readily form; and removing the carbon blocking mask.
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Citations
37 Claims
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1. An article comprising:
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a body comprising a metal alloy; a first portion of said body having a first hardness characteristic; and a second portion of said body having a second hardness characteristic; said second portion being less than the entire body and comprising a carburized surface area substantially free of carbides. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 28, 29, 30, 31)
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9. An article comprising:
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a body comprising a chromium bearing alloy; a first portion of said body having a first hardness characteristic; and a second portion of said body less than the entire body with said second portion being carbon hardened compared to said first portion and being substantially free of carbides. - View Dependent Claims (10, 11)
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12. A method for selectively carburizing a chromium bearing article, the method comprising:
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disposing a carbon blocking mask over a selected surface portion of the article; activating an unmasked surface portion of the article; and carburizing said unmasked portion of the article substantially free of carbides. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 25, 26, 27)
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23. An article made by the following process:
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disposing a carbon blocking mask over a selected surface portion of the article; activating an unmasked surface portion of the article; carburizing said unmasked portion of the article using a time-temperature profile that substantially prevents the formation of carbides. - View Dependent Claims (24)
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- 32. An article comprising a shaped mass of stainless steel alloy defining a first surface area and a second surface area different from the first surface area, the second surface area being carburized, harder than the first surface area and substantially free of carbides.
Specification