A.電渣焊 B.埋弧焊 C.手弧焊 D.鋁熱焊
A.弧長(zhǎng)不變 B.弧長(zhǎng)減小 C.弧長(zhǎng)拉長(zhǎng) D.弧長(zhǎng)波動(dòng)
A.15錳釩氮 B.18錳鉬鈮 C.20錳鉬 D.16錳釩