鎢(wu)(wu)極(ji)惰(duo)性(xing)氣(qi)(qi)(qi)體保護(hu)(hu)(hu)電(dian)(dian)弧焊(han)(han)(han)（tungsten inert gas welding，TIG），從屬(shu)于(yu)GTAW中(zhong)的(de)(de)非熔(rong)化(hua)極(ji)惰(duo)性(xing)氣(qi)(qi)(qi)體保護(hu)(hu)(hu)焊(han)(han)(han)，焊(han)(han)(han)接時(shi)(shi)鎢(wu)(wu)極(ji)只起導電(dian)(dian)作用(yong)(yong)，不(bu)作填(tian)充金(jin)屬(shu)（不(bu)熔(rong)化(hua)），如圖4-30所(suo)示。根據保護(hu)(hu)(hu)氣(qi)(qi)(qi)體的(de)(de)不(bu)同，分為鎢(wu)(wu)極(ji)氬(ya)(ya)弧焊(han)(han)(han)和鎢(wu)(wu)極(ji)氦弧焊(han)(han)(han)。焊(han)(han)(han)接時(shi)(shi)，惰(duo)性(xing)氣(qi)(qi)(qi)體氬(ya)(ya)氣(qi)(qi)(qi)或(huo)(huo)(huo)氦氣(qi)(qi)(qi)（Ar或(huo)(huo)(huo)He）通(tong)過焊(han)(han)(han)槍或(huo)(huo)(huo)其他裝置(zhi)(zhi)加(jia)入焊(han)(han)(han)接區（或(huo)(huo)(huo)待焊(han)(han)(han)區），鎢(wu)(wu)極(ji)與被焊(han)(han)(han)工件(jian)之間通(tong)電(dian)(dian)產生(sheng)電(dian)(dian)弧，電(dian)(dian)弧在惰(duo)性(xing)氣(qi)(qi)(qi)體的(de)(de)氣(qi)(qi)(qi)氛(fen)中(zhong)燃(ran)燒(shao)。氬(ya)(ya)氣(qi)(qi)(qi)或(huo)(huo)(huo)氦氣(qi)(qi)(qi)（Ar或(huo)(huo)(huo)He）在焊(han)(han)(han)接過程中(zhong)與鎢(wu)(wu)極(ji)、焊(han)(han)(han)件(jian)、填(tian)充焊(han)(han)(han)絲(si)不(bu)發(fa)生(sheng)任何(he)化(hua)學、冶金(jin)作用(yong)(yong)、惰(duo)性(xing)氣(qi)(qi)(qi)體保護(hu)(hu)(hu)焊(han)(han)(han)的(de)(de)顯(xian)著(zhu)特點(dian)是(shi)電(dian)(dian)弧燃(ran)燒(shao)穩定，能(neng)有效地隔絕周圍空氣(qi)(qi)(qi)，使熔(rong)池、填(tian)充絲(si)不(bu)被氧化(hua)和氮化(hua)，因(yin)而能(neng)獲(huo)得(de)高質(zhi)量焊(han)(han)(han)縫(feng)，且(qie)能(neng)進行全(quan)位置(zhi)(zhi)焊(han)(han)(han)接。但(dan)鎢(wu)(wu)極(ji)所(suo)通(tong)過的(de)(de)電(dian)(dian)流(liu)密度受到限制，若通(tong)過電(dian)(dian)流(liu)密度太大(da)(da)，鎢(wu)(wu)極(ji)會燒(shao)損，使焊(han)(han)(han)縫(feng)金(jin)屬(shu)產生(sheng)夾鎢(wu)(wu)缺欠(qian)。由于(yu)鎢(wu)(wu)極(ji)氬(ya)(ya)弧焊(han)(han)(han)電(dian)(dian)弧能(neng)量密度低，也不(bu)能(neng)獲(huo)得(de)較大(da)(da)的(de)(de)熔(rong)深(shen)和較高的(de)(de)生(sheng)產率。采(cai)用(yong)(yong)鎢(wu)(wu)極(ji)氦弧焊(han)(han)(han)時(shi)(shi)，使用(yong)(yong)與鎢(wu)(wu)極(ji)氬(ya)(ya)弧焊(han)(han)(han)同樣(yang)的(de)(de)電(dian)(dian)流(liu)密度，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。

  鎢極氬(ya)弧(hu)焊(han)(han)(han)(han)(han)(han)(han)時，母(mu)材(cai)金屬加熱特點（主要指(zhi)能量密度和(he)熱功率大小）介于氣(qi)焊(han)(han)(han)(han)(han)(han)(han)和(he)焊(han)(han)(han)(han)(han)(han)(han)條(tiao)電(dian)(dian)弧(hu)焊(han)(han)(han)(han)(han)(han)(han)之間，在(zai)(zai)很小的(de)(de)焊(han)(han)(han)(han)(han)(han)(han)接(jie)(jie)電(dian)(dian)流（≤10A）下，電(dian)(dian)弧(hu)仍可穩定(ding)燃燒，特別適(shi)于焊(han)(han)(han)(han)(han)(han)(han)接(jie)(jie)薄件(jian)或(huo)超(chao)薄件(jian)奧(ao)氏體型不(bu)銹鋼的(de)(de)焊(han)(han)(han)(han)(han)(han)(han)接(jie)(jie)構件(jian)。鎢極氬(ya)弧(hu)焊(han)(han)(han)(han)(han)(han)(han)時能清晰地觀察到焊(han)(han)(han)(han)(han)(han)(han)接(jie)(jie)熔池和(he)熔透情(qing)況(kuang)、因(yin)此，在(zai)(zai)要求(qiu)保證焊(han)(han)(han)(han)(han)(han)(han)透及要求(qiu)背面成形的(de)(de)情(qing)況(kuang)下，單面焊(han)(han)(han)(han)(han)(han)(han)采用(yong)內壁(bi)（或(huo)背面）通氬(ya)氣(qi)的(de)(de)鎢極氬(ya)弧(hu)打底焊(han)(han)(han)(han)(han)(han)(han)的(de)(de)方法(fa)，在(zai)(zai)國內外已得到普遍應用(yong)。鎢極氬(ya)弧(hu)焊(han)(han)(han)(han)(han)(han)(han)采用(yong)的(de)(de)填(tian)充絲為裸焊(han)(han)(han)(han)(han)(han)(han)絲，在(zai)(zai)施焊(han)(han)(han)(han)(han)(han)(han)過程(cheng)中(zhong)，不(bu)會產生飛濺、焊(han)(han)(han)(han)(han)(han)(han)縫成形美觀，焊(han)(han)(han)(han)(han)(han)(han)縫上(shang)不(bu)存在(zai)(zai)渣殼(ke)，焊(han)(han)(han)(han)(han)(han)(han)后不(bu)需清理。

  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）。