prehardening

例句：

1. 1. The steel is prehardened before being machined.
   钢材在加工前进行预硬化处理。
2. 2. The process of prehardening is crucial for the final quality of the product.
   预硬化过程对产品最终质量至关重要。
3. 3. In this case, prehardening was done to improve the material's strength and durability.
   在这种情况下，进行了预硬化处理以增强材料的强度和耐用性。