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體(ti)不銹鋼的焊接參數見表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(zai)熔(rong)化(hua)極(ji)氬(ya)氣(qi)(qi)保(bao)護(hu)焊(han)(han)(han)(han)(han)(han)的基礎上(shang)加(jia)入(ru)(ru)脈沖(chong)(chong)(chong)電流即成(cheng)脈沖(chong)(chong)(chong)熔(rong)化(hua)極(ji)氬(ya)弧焊(han)(han)(han)(han)(han)(han)，它不僅(jin)具有熔(rong)化(hua)極(ji)氬(ya)氣(qi)(qi)保(bao)護(hu)焊(han)(han)(han)(han)(han)(han)的所有特點(dian)，同(tong)時(shi)(shi)能控制焊(han)(han)(han)(han)(han)(han)接(jie)(jie)熱(re)輸(shu)入(ru)(ru)，控制金(jin)屬熔(rong)池，使焊(han)(han)(han)(han)(han)(han)縫(feng)正反面成(cheng)形良好，實現(xian)單面焊(han)(han)(han)(han)(han)(han)背(bei)面成(cheng)形。表4-46為脈沖(chong)(chong)(chong)熔(rong)化(hua)極(ji)氬(ya)弧焊(han)(han)(han)(han)(han)(han)的單面焊(han)(han)(han)(han)(han)(han)背(bei)面成(cheng)形對(dui)接(jie)(jie)焊(han)(han)(han)(han)(han)(han)縫(feng)的焊(han)(han)(han)(han)(han)(han)接(jie)(jie)參(can)數。表4-47為脈沖(chong)(chong)(chong)熔(rong)化(hua)極(ji)氬(ya)弧焊(han)(han)(han)(han)(han)(han)焊(han)(han)(han)(han)(han)(han)接(jie)(jie)角焊(han)(han)(han)(han)(han)(han)縫(feng)的焊(han)(han)(han)(han)(han)(han)接(jie)(jie)參(can)數。在(zai)焊(han)(han)(han)(han)(han)(han)接(jie)(jie)同(tong)樣厚度(du)的材料時(shi)(shi)，焊(han)(han)(han)(han)(han)(han)接(jie)(jie)熱(re)輸(shu)入(ru)(ru)比非(fei)脈沖(chong)(chong)(chong)熔(rong)化(hua)極(ji)焊(han)(han)(han)(han)(han)(han)小(xiao)，相應地減(jian)少了(le)熱(re)影響區，有利(li)于(yu)提高(gao)耐腐蝕性能；同(tong)時(shi)(shi)減(jian)少了(le)焊(han)(han)(han)(han)(han)(han)接(jie)(jie)應力與變(bian)形。脈沖(chong)(chong)(chong)電流的熱(re)循環對(dui)金(jin)屬熔(rong)池能起到攪拌作用(yong)，有利(li)于(yu)細化(hua)焊(han)(han)(han)(han)(han)(han)縫(feng)結晶，降低(di)產(chan)生裂紋(wen)的傾向。此外，這種焊(han)(han)(han)(han)(han)(han)接(jie)(jie)方(fang)法可(ke)以減(jian)輕勞動強度(du)，提高(gao)生產(chan)效率。