钢的热处理工序包括硬化、回火、退火和表面硬化。
The procedures of heat treatment of steel include hardening tempering annealing and case hardening.
退火工艺的组成为把钢加热到一定温度并保持一段时间，通常再缓慢冷却。
The process of annealing consists of heating the steel to an elevated temperature for a definite period of time and, usually, cooling it slowly.
达到退火温度后，钢应当保持在此温度等到全部均匀受热。
When the annealing temperature has been reached, the steel should be held there until it is uniform throughout.
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