Stress relieved grinding ball having hard outer shell

  • US 6,632,303 B2
  • Filed: 01/10/2001
  • Issued: 10/14/2003
  • Est. Priority Date: 01/10/2000
  • Status: Expired due to Term
First Claim
Patent Images

1. A process for making a grinding ball having a hardened section of tempered martensite wherein said ball has been stress relieved to stabilize said ball against break up and/or spalling, said process comprising:

  • i) reheating a tempered grinding ball having a hardened section of tempered mantensite to its previous equalization temperature of its earlier tempering process;

    ii) holding the grinding ball at the equalization temperature for a period of time sufficient to relieve partially compressive stresses in the tempered martensite section to develop an outer stress relieved martensitic shell and an inner non-stress relieved martensitic section; and

    iii) allowing the reheated stress relieved ball to cool.

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