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Method for modifying and thereby improving the corrosion resistance and hardness of workpieces of ferritic steel

  • US 5,196,075 A
  • Filed: 01/27/1992
  • Issued: 03/23/1993
  • Est. Priority Date: 02/17/1988
  • Status: Expired due to Term
First Claim
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1. A method for modifying and thereby improving the corrosion resistance and hardness of workpieces of ferritic steel, comprising the steps of:

  • forming a workpiece core from a ferritic chrome steel having a chrome percentage by weight of at least 13%;

    providing said workpiece core with an outer layer of nickel, said outer layer having a thickness of at least 5 μ

    m; and

    diffusion annealing said workpiece under an oxygen-free environment a at at least 850°

    C. so as to form an intermediate austenitic chrome-nickel alloyed layer between said chrome steel core and said outer layer of nickel which provides said workpiece with a desired corrosion resistance while said chrome steel core is changed from ferritic chrome steel to martensitic chrome steel which provides said workpiece with a desired degree of hardness.

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