三个过程：它们是淬火、回火和退火。

Three:they are hardening, temper and anneal.

youdao

钢的热处理操作主要有三种，即：淬火、回火和退火。

There are three main operations in the heat treatment of steel: hardening tempering and annealing.

youdao

钢的热处理操作主要有三种，即：淬火，回火和退火。

There are three main operations in the heat treatment of steel: hardening, tempering and annealing.

youdao