Stationary roller shaft formed of a material having a low inclusion content and high hardness

  • US 6,892,455 B1
  • Filed: 03/31/2003
  • Issued: 05/17/2005
  • Est. Priority Date: 11/20/2001
  • Status: Active Grant
First Claim
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1. A method for fabricating a stationary roller shaft for a turbine starter, the method comprising:

  • obtaining a predetermined material having a low inclusion content wherein the predetermined material consists essentially of in, weight percent, form 1.30% to 1.40% carbon, from 0.15% to 0.40% manganese, from 0.15% to 0.40% silicon, from 3.50% to 4.25% chromium, from 1.75% to 2.25% vanadium, from 5.75% to 6.75% tungsten, from 10.0% to 11.0% molybdenum, a maximum of approximately 0.04% sulfur, a maximum of approximately 0.03% phosphorous, a minimum of approximately 0.035% nitrogen, and the balance iron;

    machining the stationary roller shaft from the material such that the shaft is homogenous with respect to the predetermined material; and

    treating the stationary roller shaft to achieve a hardness of at least 66 Rockwell C.

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