奧氏體不銹鋼采用手工鎢極氬弧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(gen)據接頭的(de)形(xing)式(shi)，平(ping)焊(han)(han)位置(zhi)包括對接平(ping)焊(han)(han)和平(ping)角焊(han)(han)兩種(zhong)。

①. 對接平(ping)焊

 焊(han)(han)件在裝配(pei)時(shi)，為了防止(zhi)焊(han)(han)接過程中產生變形，應放在夾(jia)具中緊固(gu)，并在焊(han)(han)件坡口(kou)背面安放墊(dian)板(ban)，墊(dian)板(ban)上(shang)應開設凹槽，內通氬(ya)氣，保護背面焊(han)(han)縫，如圖(tu)4-11所示(shi)。

  焊(han)接時(shi)，首先在定位焊(han)縫根部后10mm左(zuo)(zuo)右處開始(shi)引燃電弧，運弧至(zhi)定位焊(han)點根部，此(ci)(ci)時(shi)焊(han)槍畫一個(ge)半(ban)圓形的圈，在坡口根部形成(cheng)一個(ge)熔(rong)孔，熔(rong)孔形成(cheng)后向(xiang)(xiang)右側(ce)鈍邊處填(tian)加焊(han)絲，然后得(de)向(xiang)(xiang)左(zuo)(zuo)側(ce)運弧，向(xiang)(xiang)左(zuo)(zuo)側(ce)鈍邊處填(tian)加焊(han)絲，再向(xiang)(xiang)右運弧，如此(ci)(ci)往復循環，逐漸形成(cheng)熔(rong)透焊(han)縫。

  操作過程中(zhong)要(yao)保(bao)持(chi)熔孔(kong)(kong)(kong)始終(zhong)深(shen)入母材(cai)0.5~1.0mm,出現熔孔(kong)(kong)(kong)后應(ying)立(li)即(ji)填充(chong)焊(han)(han)(han)(han)(han)絲(si)，這時形(xing)成的焊(han)(han)(han)(han)(han)縫才(cai)會均勻。如果填充(chong)焊(han)(han)(han)(han)(han)絲(si)過遲，熔孔(kong)(kong)(kong)過大，反面(mian)焊(han)(han)(han)(han)(han)縫就過高，甚(shen)至(zhi)產生焊(han)(han)(han)(han)(han)瘤；填充(chong)焊(han)(han)(han)(han)(han)絲(si)過早，若(ruo)還未(wei)(wei)形(xing)成熔孔(kong)(kong)(kong)，就會產生未(wei)(wei)焊(han)(han)(han)(han)(han)透。焊(han)(han)(han)(han)(han)接(jie)過程中(zhong)在不影響視線的情況下(xia)盡(jin)量采用短弧(hu)，以增強氬氣的保(bao)護效(xiao)果和提高電(dian)弧(hu)的穿透能力。鎢極(ji)端部距熔池表(biao)面(mian)以2~3mm為宜，要(yao)注意觀察熔池的形(xing)狀，熔池應(ying)保(bao)持(chi)與焊(han)(han)(han)(han)(han)縫軸(zhou)線對稱，否則焊(han)(han)(han)(han)(han)縫就會偏斜。

  熔(rong)(rong)(rong)(rong)透(tou)的識(shi)別：焊(han)(han)(han)接過程中應通過仔細觀察熔(rong)(rong)(rong)(rong)池(chi)(chi)的變化來判斷(duan)是(shi)否熔(rong)(rong)(rong)(rong)透(tou)，以達到單面(mian)焊(han)(han)(han)雙面(mian)成形的目的。當(dang)填充(chong)焊(han)(han)(han)絲上一(yi)顆熔(rong)(rong)(rong)(rong)滴(di)落(luo)入(ru)熔(rong)(rong)(rong)(rong)池(chi)(chi)時，熔(rong)(rong)(rong)(rong)池(chi)(chi)表(biao)面(mian)位置就會(hui)升高(gao)，隨著熱量向下(xia)傳輸(shu)，基本金屬熔(rong)(rong)(rong)(rong)化形成熔(rong)(rong)(rong)(rong)孔。由于重力使熔(rong)(rong)(rong)(rong)池(chi)(chi)下(xia)沉(chen)(chen)，于是(shi)熔(rong)(rong)(rong)(rong)池(chi)(chi)水平(ping)下(xia)降，熔(rong)(rong)(rong)(rong)池(chi)(chi)表(biao)面(mian)積(ji)擴張，這是(shi)焊(han)(han)(han)透(tou)的重要標(biao)志。如果沒有焊(han)(han)(han)透(tou)，熔(rong)(rong)(rong)(rong)池(chi)(chi)便不(bu)會(hui)下(xia)沉(chen)(chen)。

  當運弧至終焊(han)(han)端的定(ding)位焊(han)(han)縫根(gen)部3~5mm時(shi)，焊(han)(han)槍畫(hua)圈，把(ba)定(ding)位焊(han)(han)縫根(gen)部熔化，然后(hou)(hou)填(tian)充2~3滴熔滴，繼續向前(qian)施(shi)焊(han)(han)10mm左右，把(ba)定(ding)位焊(han)(han)縫表面熔化，最后(hou)(hou)用電流(liu)衰減(jian)法收弧。收弧焊(han)(han)縫應(ying)在定(ding)位焊(han)(han)縫后(hou)(hou)方10mm左右處，以保證接頭部位能焊(han)(han)透(tou)。

②. 平(ping)角(jiao)焊

  操作時，焊(han)槍、焊(han)絲和焊(han)件之間的相對位置如圖4-12所示。電弧長度1.5mm左右，焊(han)槍與焊(han)件的傾(qing)角為40°~50°,焊(han)絲送入傾(qing)角為15°~20°。