welding backing

例句：

1. 1.The welding backing was designed to protect the metal from heat and stress.
   焊接衬垫的设计是为了保护金属免受热量和应力的影响。
2. 2. The welding backing was used to reinforce the joint between two pieces of metal.
   焊接衬垫被用来加固两块金属之间的接合处。
3. 3.The welding backing was removed before the final assembly of the machine.
   在最终组装机器之前，需要移除焊接衬垫。