austemper case hardening

例句：

1. 1.The steel was tempered to improve its strength and toughness.
   钢材经过淬火以提高其强度和韧性。
2. 2. The process of tempering involves heating the metal and then cooling it quickly.
   回火过程涉及加热金属并迅速冷却。
3. 3. Austenite is a type of steel that has been tempered to achieve a specific hardness.
   奥氏体是一种经过淬火达到特定硬度的钢。