定義

• Quenching Crack.  A fracture in a die caused during tempering. If the die is not a uniform temperature during heat treating (or the liquid not of uniform temperature during quenching) the die fractures because it does not cool uniformly.

  excerpted with permission from

  An Encyclopedia of Coin and Medal Technology

  For Artists, Makers, Collectors and Curators

  COMPILED AND WRITTEN BY D. WAYNE JOHNSON

  Roger W. Burdette, Editor

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