奧氏體不銹鋼采用手工鎢(wu)極(ji)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。

  根據接頭的(de)形式，平焊位置包(bao)括對接平焊和平角焊兩種。

①. 對(dui)接平焊(han)

 焊件(jian)在(zai)裝配時，為(wei)了防止(zhi)焊接過程中產(chan)生變形，應(ying)放在(zai)夾具(ju)中緊(jin)固，并在(zai)焊件(jian)坡口(kou)背面安放墊板，墊板上應(ying)開設(she)凹槽(cao)，內通(tong)氬(ya)氣，保護背面焊縫，如圖4-11所示(shi)。

  焊接時，首先在定位焊縫根部(bu)后(hou)(hou)(hou)10mm左右處(chu)開始(shi)引(yin)燃電弧，運弧至定位焊點根部(bu)，此時焊槍畫一個半圓形的(de)圈，在坡(po)口(kou)根部(bu)形成一個熔(rong)孔，熔(rong)孔形成后(hou)(hou)(hou)向(xiang)(xiang)右側鈍(dun)邊處(chu)填(tian)加(jia)焊絲，然后(hou)(hou)(hou)得(de)向(xiang)(xiang)左側運弧，向(xiang)(xiang)左側鈍(dun)邊處(chu)填(tian)加(jia)焊絲，再向(xiang)(xiang)右運弧，如此往復循(xun)環，逐漸形成熔(rong)透焊縫。

  操作過(guo)程中要(yao)保持熔(rong)(rong)孔(kong)始終(zhong)深入母材0.5~1.0mm,出現熔(rong)(rong)孔(kong)后應立(li)即(ji)填充(chong)焊(han)(han)(han)絲(si)，這時形(xing)成的(de)焊(han)(han)(han)縫(feng)才(cai)會均(jun)勻。如果(guo)填充(chong)焊(han)(han)(han)絲(si)過(guo)遲(chi)，熔(rong)(rong)孔(kong)過(guo)大，反(fan)面焊(han)(han)(han)縫(feng)就(jiu)過(guo)高(gao)，甚至產生(sheng)焊(han)(han)(han)瘤；填充(chong)焊(han)(han)(han)絲(si)過(guo)早，若還未形(xing)成熔(rong)(rong)孔(kong)，就(jiu)會產生(sheng)未焊(han)(han)(han)透。焊(han)(han)(han)接過(guo)程中在(zai)不影響視線的(de)情況下(xia)盡量采用(yong)短弧(hu)(hu)，以(yi)增強氬氣的(de)保護效(xiao)果(guo)和提高(gao)電弧(hu)(hu)的(de)穿(chuan)透能(neng)力。鎢極(ji)端部(bu)距熔(rong)(rong)池(chi)(chi)表(biao)面以(yi)2~3mm為宜，要(yao)注意(yi)觀(guan)察熔(rong)(rong)池(chi)(chi)的(de)形(xing)狀，熔(rong)(rong)池(chi)(chi)應保持與焊(han)(han)(han)縫(feng)軸線對稱，否則焊(han)(han)(han)縫(feng)就(jiu)會偏斜。

  熔(rong)(rong)(rong)透的(de)(de)識別：焊(han)接過程中應通(tong)過仔(zi)細觀察熔(rong)(rong)(rong)池(chi)的(de)(de)變化(hua)(hua)來判斷是(shi)否熔(rong)(rong)(rong)透，以達到單面(mian)(mian)焊(han)雙面(mian)(mian)成形(xing)(xing)的(de)(de)目的(de)(de)。當(dang)填充焊(han)絲上一(yi)顆熔(rong)(rong)(rong)滴落入熔(rong)(rong)(rong)池(chi)時(shi)，熔(rong)(rong)(rong)池(chi)表(biao)面(mian)(mian)位(wei)置就會升高(gao)，隨著熱量向下傳輸，基本(ben)金屬熔(rong)(rong)(rong)化(hua)(hua)形(xing)(xing)成熔(rong)(rong)(rong)孔。由(you)于(yu)重(zhong)力使(shi)熔(rong)(rong)(rong)池(chi)下沉，于(yu)是(shi)熔(rong)(rong)(rong)池(chi)水平下降，熔(rong)(rong)(rong)池(chi)表(biao)面(mian)(mian)積擴張，這是(shi)焊(han)透的(de)(de)重(zhong)要標志。如果沒有焊(han)透，熔(rong)(rong)(rong)池(chi)便(bian)不會下沉。

  當運弧至終焊端的定(ding)位焊縫(feng)根(gen)部(bu)3~5mm時，焊槍(qiang)畫圈，把定(ding)位焊縫(feng)根(gen)部(bu)熔(rong)化(hua)，然后(hou)(hou)填充2~3滴熔(rong)滴，繼續向前施焊10mm左右(you)，把定(ding)位焊縫(feng)表(biao)面(mian)熔(rong)化(hua)，最(zui)后(hou)(hou)用電流衰減法收(shou)弧。收(shou)弧焊縫(feng)應在定(ding)位焊縫(feng)后(hou)(hou)方10mm左右(you)處，以保證接頭(tou)部(bu)位能(neng)焊透。

②. 平角焊

  操作時(shi)，焊(han)槍、焊(han)絲和焊(han)件之(zhi)間(jian)的(de)相對(dui)位(wei)置如圖4-12所示。電弧長度(du)1.5mm左(zuo)右，焊(han)槍與焊(han)件的(de)傾(qing)角為40°~50°,焊(han)絲送(song)入傾(qing)角為15°~20°。