鎢(wu)(wu)極(ji)(ji)惰(duo)性氣(qi)(qi)(qi)體保護(hu)(hu)電(dian)(dian)(dian)弧(hu)焊(han)(han)(han)(han)(han)（tungsten inert gas welding，TIG），從屬于GTAW中(zhong)的(de)非熔(rong)化(hua)(hua)極(ji)(ji)惰(duo)性氣(qi)(qi)(qi)體保護(hu)(hu)焊(han)(han)(han)(han)(han)，焊(han)(han)(han)(han)(han)接時(shi)鎢(wu)(wu)極(ji)(ji)只起導電(dian)(dian)(dian)作(zuo)用(yong)，不(bu)作(zuo)填(tian)(tian)充金屬（不(bu)熔(rong)化(hua)(hua)），如(ru)圖4-30所(suo)示。根(gen)據保護(hu)(hu)氣(qi)(qi)(qi)體的(de)不(bu)同，分(fen)為鎢(wu)(wu)極(ji)(ji)氬(ya)(ya)弧(hu)焊(han)(han)(han)(han)(han)和(he)鎢(wu)(wu)極(ji)(ji)氦(hai)(hai)弧(hu)焊(han)(han)(han)(han)(han)。焊(han)(han)(han)(han)(han)接時(shi)，惰(duo)性氣(qi)(qi)(qi)體氬(ya)(ya)氣(qi)(qi)(qi)或(huo)氦(hai)(hai)氣(qi)(qi)(qi)（Ar或(huo)He）通(tong)(tong)過(guo)(guo)焊(han)(han)(han)(han)(han)槍或(huo)其他裝置加(jia)入焊(han)(han)(han)(han)(han)接區（或(huo)待(dai)焊(han)(han)(han)(han)(han)區），鎢(wu)(wu)極(ji)(ji)與(yu)被焊(han)(han)(han)(han)(han)工件之間(jian)通(tong)(tong)電(dian)(dian)(dian)產生(sheng)電(dian)(dian)(dian)弧(hu)，電(dian)(dian)(dian)弧(hu)在惰(duo)性氣(qi)(qi)(qi)體的(de)氣(qi)(qi)(qi)氛(fen)中(zhong)燃燒。氬(ya)(ya)氣(qi)(qi)(qi)或(huo)氦(hai)(hai)氣(qi)(qi)(qi)（Ar或(huo)He）在焊(han)(han)(han)(han)(han)接過(guo)(guo)程(cheng)中(zhong)與(yu)鎢(wu)(wu)極(ji)(ji)、焊(han)(han)(han)(han)(han)件、填(tian)(tian)充焊(han)(han)(han)(han)(han)絲不(bu)發(fa)生(sheng)任何(he)化(hua)(hua)學、冶金作(zuo)用(yong)、惰(duo)性氣(qi)(qi)(qi)體保護(hu)(hu)焊(han)(han)(han)(han)(han)的(de)顯著特點(dian)是電(dian)(dian)(dian)弧(hu)燃燒穩定，能(neng)有效(xiao)地隔絕周圍空氣(qi)(qi)(qi)，使熔(rong)池、填(tian)(tian)充絲不(bu)被氧化(hua)(hua)和(he)氮化(hua)(hua)，因而能(neng)獲得(de)高質(zhi)量焊(han)(han)(han)(han)(han)縫，且能(neng)進(jin)行全位置焊(han)(han)(han)(han)(han)接。但鎢(wu)(wu)極(ji)(ji)所(suo)通(tong)(tong)過(guo)(guo)的(de)電(dian)(dian)(dian)流(liu)密(mi)度受(shou)到(dao)限(xian)制(zhi)，若通(tong)(tong)過(guo)(guo)電(dian)(dian)(dian)流(liu)密(mi)度太大，鎢(wu)(wu)極(ji)(ji)會燒損(sun)，使焊(han)(han)(han)(han)(han)縫金屬產生(sheng)夾(jia)鎢(wu)(wu)缺欠。由于鎢(wu)(wu)極(ji)(ji)氬(ya)(ya)弧(hu)焊(han)(han)(han)(han)(han)電(dian)(dian)(dian)弧(hu)能(neng)量密(mi)度低，也不(bu)能(neng)獲得(de)較(jiao)大的(de)熔(rong)深(shen)和(he)較(jiao)高的(de)生(sheng)產率(lv)。采用(yong)鎢(wu)(wu)極(ji)(ji)氦(hai)(hai)弧(hu)焊(han)(han)(han)(han)(han)時(shi)，使用(yong)與(yu)鎢(wu)(wu)極(ji)(ji)氬(ya)(ya)弧(hu)焊(han)(han)(han)(han)(han)同樣的(de)電(dian)(dian)(dian)流(liu)密(mi)度，鎢極氦弧焊的電弧電壓較高，電弧熱功率高。氦氣作為熱能的載體，它的熱傳導能比氬氣約大9倍。這樣，就有大量的熱能輸送到焊接熔池中去，從而獲得較大的熔深和得到較高的生產率。但是氦氣來源較為困難，價格比氬氣高20～30倍、同時氦氣的密度比氬氣小，要達到同樣的保護效果，氦氣的消耗量高出很多，所以氨弧焊成本很高。焊接薄的和中等厚度的奧氏體型不(bu)銹鋼板一般極少采用，只有在焊接關鍵焊件時才使用氦弧焊。

  鎢(wu)(wu)極氬(ya)(ya)(ya)弧(hu)(hu)(hu)焊(han)(han)(han)(han)(han)時，母材金屬加熱(re)特點（主要指能(neng)量密度和(he)熱(re)功率大小）介于氣焊(han)(han)(han)(han)(han)和(he)焊(han)(han)(han)(han)(han)條電弧(hu)(hu)(hu)焊(han)(han)(han)(han)(han)之間，在很(hen)小的(de)(de)焊(han)(han)(han)(han)(han)接電流（≤10A）下，電弧(hu)(hu)(hu)仍可(ke)穩定燃燒，特別適(shi)于焊(han)(han)(han)(han)(han)接薄(bo)件(jian)或超薄(bo)件(jian)奧氏體型不銹鋼的(de)(de)焊(han)(han)(han)(han)(han)接構件(jian)。鎢(wu)(wu)極氬(ya)(ya)(ya)弧(hu)(hu)(hu)焊(han)(han)(han)(han)(han)時能(neng)清晰(xi)地觀(guan)察(cha)到焊(han)(han)(han)(han)(han)接熔池和(he)熔透情況、因此，在要求(qiu)保證(zheng)焊(han)(han)(han)(han)(han)透及要求(qiu)背面成(cheng)形(xing)的(de)(de)情況下，單面焊(han)(han)(han)(han)(han)采用內壁（或背面）通氬(ya)(ya)(ya)氣的(de)(de)鎢(wu)(wu)極氬(ya)(ya)(ya)弧(hu)(hu)(hu)打底焊(han)(han)(han)(han)(han)的(de)(de)方法(fa)，在國(guo)內外(wai)已得(de)到普遍應(ying)用。鎢(wu)(wu)極氬(ya)(ya)(ya)弧(hu)(hu)(hu)焊(han)(han)(han)(han)(han)采用的(de)(de)填(tian)充絲為裸焊(han)(han)(han)(han)(han)絲，在施焊(han)(han)(han)(han)(han)過程中(zhong)，不會產生飛濺、焊(han)(han)(han)(han)(han)縫(feng)成(cheng)形(xing)美觀(guan)，焊(han)(han)(han)(han)(han)縫(feng)上不存在渣(zha)殼，焊(han)(han)(han)(han)(han)后不需清理(li)。

  鎢極氬弧焊電弧的熱功率低，焊接速度相對其他電弧焊而言比較小，由于奧氏體不銹(xiu)鋼管導熱能力較差，如鎢極氬弧焊的焊接速度很慢時、會導致焊接接頭冷卻速度緩慢，在400～800℃的危險溫度區間停留時間較長，會影響焊接接頭耐腐蝕能力（包括晶間腐蝕和均勻腐蝕）。