concave filler weld

例句：

1. 1. The engineer used a special tool to create the concave filler weld on the car body.
   工程师使用一种特殊的工具在汽车车身创建凹形填充焊接。
2. 2. The concave filler weld was designed to strengthen the structure and prevent leaks.
   凹形填充焊接的设计是为了加强结构并防止泄漏。
3. 3.The concave filler welding process is crucial for the safety of the construction site.
   凹形填充焊接过程对于施工现场的安全至关重要。