heat hardening

• 淬火

heat hardening的用法和样例：

例句

1. So we find that hardening operation is made up of heating and quenching.
   因此我们发现淬火工序包括加热和淬硬两个步骤。
2. Its original heat treament processes were graphitizing annealing,quenching and tempering,then high-frequency hardening.
   同时因齿条形状特殊，高频淬火时易将齿部完全淬透，不能满足用户要求。