奧氏體不銹鋼采用手工鎢極氬(ya)弧(hu)焊可以進行各種位置的操作，其中包括水平固定管（全位置）的對接焊，但主適用于薄壁件和打底層的焊接。

  根據(ju)接頭的形式(shi)，平焊(han)(han)位置包(bao)括對接平焊(han)(han)和平角焊(han)(han)兩(liang)種。

①. 對接平(ping)焊(han)

 焊(han)件(jian)在裝(zhuang)配時，為(wei)了防止焊(han)接過程中(zhong)產生變形，應放在夾具中(zhong)緊固，并在焊(han)件(jian)坡口背面安放墊板，墊板上應開設凹槽，內通氬氣，保護(hu)背面焊(han)縫，如(ru)圖4-11所示(shi)。

  焊(han)接時(shi)(shi)，首先在(zai)定(ding)位焊(han)縫(feng)根(gen)(gen)(gen)部(bu)后(hou)10mm左右(you)處(chu)開始引燃電弧，運弧至定(ding)位焊(han)點根(gen)(gen)(gen)部(bu)，此時(shi)(shi)焊(han)槍(qiang)畫(hua)一個(ge)半(ban)圓形(xing)(xing)的圈，在(zai)坡口根(gen)(gen)(gen)部(bu)形(xing)(xing)成一個(ge)熔孔(kong)，熔孔(kong)形(xing)(xing)成后(hou)向(xiang)右(you)側鈍邊處(chu)填加焊(han)絲，然后(hou)得向(xiang)左側運弧，向(xiang)左側鈍邊處(chu)填加焊(han)絲，再向(xiang)右(you)運弧，如此往(wang)復循環(huan)，逐漸形(xing)(xing)成熔透焊(han)縫(feng)。

  操(cao)作過(guo)(guo)(guo)程中要保持熔(rong)(rong)孔始(shi)終深入(ru)母材0.5~1.0mm,出現熔(rong)(rong)孔后應立即填充焊(han)絲，這時形(xing)(xing)(xing)成(cheng)的(de)(de)焊(han)縫(feng)才會均勻。如果(guo)填充焊(han)絲過(guo)(guo)(guo)遲，熔(rong)(rong)孔過(guo)(guo)(guo)大(da)，反(fan)面焊(han)縫(feng)就(jiu)(jiu)過(guo)(guo)(guo)高，甚至產生(sheng)焊(han)瘤；填充焊(han)絲過(guo)(guo)(guo)早(zao)，若(ruo)還未形(xing)(xing)(xing)成(cheng)熔(rong)(rong)孔，就(jiu)(jiu)會產生(sheng)未焊(han)透。焊(han)接過(guo)(guo)(guo)程中在不影響視線的(de)(de)情況下(xia)盡量(liang)采(cai)用短弧，以增強氬氣的(de)(de)保護效果(guo)和提高電(dian)弧的(de)(de)穿透能力。鎢極端部距(ju)熔(rong)(rong)池(chi)表面以2~3mm為宜，要注(zhu)意觀察熔(rong)(rong)池(chi)的(de)(de)形(xing)(xing)(xing)狀，熔(rong)(rong)池(chi)應保持與焊(han)縫(feng)軸線對稱，否則焊(han)縫(feng)就(jiu)(jiu)會偏(pian)斜。

  熔(rong)(rong)(rong)透(tou)(tou)的(de)識別：焊接過程中應通(tong)過仔細觀察(cha)熔(rong)(rong)(rong)池(chi)的(de)變(bian)化來判(pan)斷是(shi)否熔(rong)(rong)(rong)透(tou)(tou)，以達到單面焊雙面成形(xing)(xing)的(de)目的(de)。當填充(chong)焊絲上(shang)一顆熔(rong)(rong)(rong)滴落入熔(rong)(rong)(rong)池(chi)時，熔(rong)(rong)(rong)池(chi)表面位置(zhi)就會升高(gao)，隨著熱量向下傳輸，基本金屬熔(rong)(rong)(rong)化形(xing)(xing)成熔(rong)(rong)(rong)孔。由于重力使熔(rong)(rong)(rong)池(chi)下沉(chen)(chen)，于是(shi)熔(rong)(rong)(rong)池(chi)水平下降，熔(rong)(rong)(rong)池(chi)表面積擴張，這(zhe)是(shi)焊透(tou)(tou)的(de)重要標志。如果沒有(you)焊透(tou)(tou)，熔(rong)(rong)(rong)池(chi)便不會下沉(chen)(chen)。

  當運弧(hu)至終焊(han)端的定位(wei)焊(han)縫根部(bu)3~5mm時(shi)，焊(han)槍(qiang)畫圈，把定位(wei)焊(han)縫根部(bu)熔化(hua)，然后(hou)填充2~3滴熔滴，繼續向(xiang)前(qian)施焊(han)10mm左(zuo)右，把定位(wei)焊(han)縫表面熔化(hua)，最后(hou)用電流衰減(jian)法(fa)收(shou)弧(hu)。收(shou)弧(hu)焊(han)縫應在(zai)定位(wei)焊(han)縫后(hou)方10mm左(zuo)右處，以保證接頭部(bu)位(wei)能(neng)焊(han)透。

②. 平角(jiao)焊

  操作時，焊(han)(han)(han)(han)槍、焊(han)(han)(han)(han)絲和焊(han)(han)(han)(han)件(jian)(jian)之間的相(xiang)對(dui)位置如(ru)圖4-12所(suo)示(shi)。電(dian)弧長度1.5mm左右，焊(han)(han)(han)(han)槍與焊(han)(han)(han)(han)件(jian)(jian)的傾角為40°~50°,焊(han)(han)(han)(han)絲送入傾角為15°~20°。