埋弧焊焊接奧氏體型不銹鋼管施焊工藝、程序基本與焊接碳鋼管相同,大致有以下幾種。
①. 焊條電弧(hu)焊與埋(mai)弧(hu)焊組合施焊
先用(yong)焊(han)(han)條電弧(hu)焊(han)(han)打底(di)焊(han)(han)(backing welding),要求焊(han)(han)條電弧(hu)焊(han)(han)的(de)熔深達到板厚的(de)1/3,焊(han)(han)完以后,清(qing)理焊(han)(han)縫。清(qing)除掉焊(han)(han)縫缺陷后,在另一方面進行(xing)埋(mai)弧(hu)焊(han)(han),如圖4-23所示(shi)。

②. 永久墊板埋(mai)弧焊
焊(han)件(jian)裝(zhuang)配時(shi)(shi)將(jiang)同種(zhong)(zhong)不(bu)銹鋼(gang)管的(de)(de)墊(dian)板(ban)緊密地貼在(zai)接頭下(xia)部用定(ding)位焊(han)固(gu)定(ding),進行單面熔(rong)透焊(han)的(de)(de)一種(zhong)(zhong)埋弧(hu)焊(han)工藝。此時(shi)(shi)要求(qiu)墊(dian)板(ban)與(yu)焊(han)件(jian)之間(jian)的(de)(de)間(jian)隙(xi)不(bu)得超過0.5~1.0mm,否則液態金屬或熔(rong)渣必然從(cong)間(jian)隙(xi)處流(liu)出或嵌入夾縫中間(jian)而造(zao)成(cheng)焊(han)接缺(que)陷。焊(han)接完(wan)畢,墊(dian)板(ban)有(you)一部分金屬被(bei)熔(rong)入焊(han)縫形(xing)成(cheng)焊(han)縫金屬,與(yu)焊(han)件(jian)牢固(gu)地焊(han)在(zai)一起。故要求(qiu)墊(dian)板(ban)的(de)(de)化學(xue)成(cheng)分、力學(xue)性能和耐(nai)腐(fu)蝕性能與(yu)焊(han)件(jian)相同。永久(jiu)墊(dian)板(ban)的(de)(de)尺(chi)寸(cun)見表4-21。永久(jiu)墊(dian)板(ban)焊(han)接時(shi)(shi)的(de)(de)裝(zhuang)配示(shi)(shi)意(yi)圖(tu)如圖(tu)4-24所示(shi)(shi)。焊(han)接壓力容器封頭與(yu)筒體的(de)(de)環焊(han)縫時(shi)(shi),如果(guo)容器內(nei)部無法施焊(han),且不(bu)會引(yin)起縫隙(xi)腐(fu)蝕時(shi)(shi),可用永久(jiu)墊(dian)板(ban)焊(han)接工藝。

③. 純銅墊埋弧焊
這種(zhong)焊(han)(han)(han)接(jie)方(fang)法(fa)能使(shi)焊(han)(han)(han)接(jie)構(gou)件(jian)達到單面(mian)焊(han)(han)(han)背(bei)面(mian)成形(xing)的(de)(de)(de)目的(de)(de)(de)。純銅墊靠焊(han)(han)(han)接(jie)夾具(ju)緊貼待焊(han)(han)(han)接(jie)頭下面(mian),它與(yu)焊(han)(han)(han)件(jian)之間(jian)的(de)(de)(de)間(jian)隙不允許大于0.5mm,各種(zhong)形(xing)式(shi)的(de)(de)(de)純銅墊結(jie)構(gou)如(ru)圖4-25所示,純銅墊板的(de)(de)(de)形(xing)狀(zhuang)和(he)尺寸(cun)見圖4-26和(he)表4-22。在純銅墊接(jie)觸焊(han)(han)(han)件(jian)的(de)(de)(de)一(yi)面(mian)開槽(cao),槽(cao)的(de)(de)(de)中心要與(yu)坡口根間(jian)隙對準,如(ru)果(guo)在槽(cao)內放焊(han)(han)(han)劑[見圖4-25(b)],則(ze)檀(tan)的(de)(de)(de)寬度和(he)深度都要相(xiang)應地加(jia)寬加(jia)深。


④. 鎖底對接接頭埋弧焊(han)
這種(zhong)焊(han)接(jie)方法適用于厚(hou)度大于10mm的構(gou)件,常(chang)用在小直徑厚(hou)壁圓筒形(xing)焊(han)件的環縫焊(han)接(jie),效(xiao)果很好。鎖底對接(jie)接(jie)頭見圖4-27。
⑤. 焊劑墊埋弧焊
這種焊(han)接方法也可使焊(han)件達(da)到單面焊(han)背面成(cheng)形(xing)(xing)的(de)(de)目的(de)(de)。根據(ju)焊(han)件厚度(du),在接縫下(xia)面墊(dian)上(shang)一(yi)層厚度(du)為30~100mm的(de)(de)焊(han)劑(ji),焊(han)劑(ji)下(xia)面是一(yi)層絕(jue)緣(yuan)的(de)(de)陶氈墊(dian),陶氈墊(dian)下(xia)面是封閉的(de)(de)橡膠管(guan),如(ru)圖(tu)(tu)4-28所(suo)示。坡(po)口根部(bu)與焊(han)劑(ji)墊(dian)中心要(yao)對中,當橡膠管(guan)一(yi)端通入壓縮(suo)空氣(qi)時(shi),焊(han)劑(ji)被均勻地向上(shang)頂緊坡(po)口的(de)(de)根部(bu)。焊(han)接時(shi),電弧將熔透(tou)焊(han)件并熔化一(yi)些焊(han)劑(ji),形(xing)(xing)成(cheng)單面焊(han)雙面成(cheng)形(xing)(xing)的(de)(de)焊(han)縫。假若焊(han)劑(ji)向上(shang)頂的(de)(de)壓力過(guo)大(da)或過(guo)小,在焊(han)縫背面會形(xing)(xing)成(cheng)凹槽或突起部(bu)分,嚴重者焊(han)縫不能成(cheng)形(xing)(xing),焊(han)劑(ji)壓力對焊(han)縫成(cheng)形(xing)(xing)的(de)(de)影(ying)響見圖(tu)(tu)4-29。

⑥. 雙面對接(jie)埋弧焊
這是(shi)埋(mai)弧焊(han)(han)(han)(han)焊(han)(han)(han)(han)接對接焊(han)(han)(han)(han)縫的一(yi)種基本方(fang)法,使用(yong)最(zui)(zui)廣。大多數中、厚板(ban)焊(han)(han)(han)(han)接時(shi)均使用(yong)雙(shuang)面(mian)(mian)(mian)(mian)焊(han)(han)(han)(han)。這種焊(han)(han)(han)(han)接接頭的幾(ji)何連續性最(zui)(zui)好(hao),承載后(hou)(hou)應(ying)(ying)力狀(zhuang)態好(hao),能適應(ying)(ying)工(gong)作負荷復(fu)雜和苛(ke)刻(ke)的工(gong)作條件。故對焊(han)(han)(han)(han)縫長度較長,分布規(gui)則的焊(han)(han)(han)(han)縫,應(ying)(ying)盡量采用(yong)這種施焊(han)(han)(han)(han)工(gong)藝方(fang)法。此時(shi)第(di)一(yi)面(mian)(mian)(mian)(mian)施焊(han)(han)(han)(han)也不(bu)用(yong)任何形(xing)式(shi)襯墊,在(zai)無(wu)墊焊(han)(han)(han)(han)接時(shi),對焊(han)(han)(han)(han)件邊(bian)緣的準備和裝(zhuang)配質量要求(qiu)(qiu)較高,希望坡口根(gen)部間隙(xi)為(wei)零(ling),局部根(gen)部間隙(xi)不(bu)得超過1.0mm,否則液體金屬容易從間隙(xi)中流出而燒穿(chuan)焊(han)(han)(han)(han)縫或形(xing)成(cheng)焊(han)(han)(han)(han)瘤。為(wei)了有一(yi)定(ding)的熔(rong)深(shen),同時(shi)又不(bu)至于焊(han)(han)(han)(han)穿(chuan),通(tong)常在(zai)第(di)一(yi)面(mian)(mian)(mian)(mian)焊(han)(han)(han)(han)接時(shi),要求(qiu)(qiu)熔(rong)深(shen)為(wei)鋼(gang)板(ban)厚度的60%~70%。如果被焊(han)(han)(han)(han)件較薄,在(zai)第(di)一(yi)面(mian)(mian)(mian)(mian)焊(han)(han)(han)(han)接時(shi),可以采取減(jian)小(xiao)焊(han)(han)(han)(han)接電流,提高焊(han)(han)(han)(han)接速度或者(zhe)焊(han)(han)(han)(han)絲向后(hou)(hou)傾斜等(deng)措施來(lai)避免燒穿(chuan)。有關奧氏體型不(bu)銹鋼(gang)中等(deng)厚度板(ban)材(cai)的無(wu)墊雙(shuang)面(mian)(mian)(mian)(mian)埋(mai)弧焊(han)(han)(han)(han)的焊(han)(han)(han)(han)接參數見表4-23。


