熔化極惰性氣體保護焊的惰性氣體，通常采用氬氣。該焊接工藝已開始在許多領域中得到使用，其中以機械操作的縱縫焊應用最多。焊接時選擇直流反極性電源，以短路過渡和噴射過渡的熔滴形式進行操作，用熔化極氬弧焊短路過渡焊接奧氏(shi)體不銹鋼(gang)的焊接參數見表4-44，用熔化極氬弧焊噴射過渡焊接奧氏體型不銹鋼的焊接參數見表4-45。

  在熔(rong)(rong)(rong)(rong)(rong)化(hua)極(ji)(ji)(ji)氬(ya)(ya)(ya)(ya)氣保護焊(han)(han)(han)(han)的(de)基礎上加入脈(mo)沖(chong)(chong)電流即成脈(mo)沖(chong)(chong)熔(rong)(rong)(rong)(rong)(rong)化(hua)極(ji)(ji)(ji)氬(ya)(ya)(ya)(ya)弧焊(han)(han)(han)(han)，它不僅具有熔(rong)(rong)(rong)(rong)(rong)化(hua)極(ji)(ji)(ji)氬(ya)(ya)(ya)(ya)氣保護焊(han)(han)(han)(han)的(de)所有特點(dian)，同時(shi)(shi)能控制焊(han)(han)(han)(han)接(jie)(jie)熱(re)輸(shu)入，控制金屬熔(rong)(rong)(rong)(rong)(rong)池(chi)，使焊(han)(han)(han)(han)縫正反面(mian)成形良好(hao)，實現單面(mian)焊(han)(han)(han)(han)背面(mian)成形。表(biao)(biao)4-46為脈(mo)沖(chong)(chong)熔(rong)(rong)(rong)(rong)(rong)化(hua)極(ji)(ji)(ji)氬(ya)(ya)(ya)(ya)弧焊(han)(han)(han)(han)的(de)單面(mian)焊(han)(han)(han)(han)背面(mian)成形對接(jie)(jie)焊(han)(han)(han)(han)縫的(de)焊(han)(han)(han)(han)接(jie)(jie)參數。表(biao)(biao)4-47為脈(mo)沖(chong)(chong)熔(rong)(rong)(rong)(rong)(rong)化(hua)極(ji)(ji)(ji)氬(ya)(ya)(ya)(ya)弧焊(han)(han)(han)(han)焊(han)(han)(han)(han)接(jie)(jie)角焊(han)(han)(han)(han)縫的(de)焊(han)(han)(han)(han)接(jie)(jie)參數。在焊(han)(han)(han)(han)接(jie)(jie)同樣厚度(du)的(de)材料時(shi)(shi)，焊(han)(han)(han)(han)接(jie)(jie)熱(re)輸(shu)入比非(fei)脈(mo)沖(chong)(chong)熔(rong)(rong)(rong)(rong)(rong)化(hua)極(ji)(ji)(ji)焊(han)(han)(han)(han)小(xiao)，相(xiang)應地減少了熱(re)影響(xiang)區，有利于提高耐腐蝕性(xing)能；同時(shi)(shi)減少了焊(han)(han)(han)(han)接(jie)(jie)應力與變形。脈(mo)沖(chong)(chong)電流的(de)熱(re)循環(huan)對金屬熔(rong)(rong)(rong)(rong)(rong)池(chi)能起到攪拌作用，有利于細化(hua)焊(han)(han)(han)(han)縫結晶，降低產生裂紋的(de)傾向。此(ci)外，這種(zhong)焊(han)(han)(han)(han)接(jie)(jie)方法可以減輕勞動強度(du)，提高生產效率。