hardening at subcritical temperature

例句：

1. 1. The material is undergoing a hardening process at subcritical temperature.
   该材料在亚临界温度下正在经历一个硬化过程。
2. 2. During the hardening process, the steel will become more durable and resistant to wear.
   在硬化过程中，钢铁将变得更耐用、更抗磨损。
3. 3. The metal was subjected to a hardening treatment to improve its strength.
   金属接受了硬化处理以增强其强度。