单项选择题
A.碳钢+0Cr13 B.碳钢 C.15CrMoR D.1Cr5Mo
A.平焊焊缝 B.搭接焊缝 C.T型连接 D.角接
A.0.5mg/L B.2mg/L C.5mg/L D.10mg/L