tempering sand

例句：

1. 1. The engineer used tempering sand to smooth the surface of the machine.
   工程师使用退火砂来平滑机器的表面。
2. 2.The metal was tempered with a mixture of iron and carbon to improve its strength.
   金属被铁和碳的混合物退火以提高其强度。
3. 3. During the manufacturing process, tempering sand is used to refine the metal before it is cut into finished products.
   在制造过程中，退火砂被用来将金属磨光，然后将其切割成成品。