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(han)條電弧(hu)焊(han)與埋弧(hu)焊(han)組合(he)施焊(han)
先(xian)用焊(han)(han)(han)(han)條電(dian)弧焊(han)(han)(han)(han)打底焊(han)(han)(han)(han)(backing welding),要求焊(han)(han)(han)(han)條電(dian)弧焊(han)(han)(han)(han)的熔(rong)深達到板厚的1/3,焊(han)(han)(han)(han)完(wan)以(yi)后,清理焊(han)(han)(han)(han)縫(feng)。清除掉焊(han)(han)(han)(han)縫(feng)缺陷后,在另一方面進行埋弧焊(han)(han)(han)(han),如圖4-23所(suo)示。

②. 永久(jiu)墊板埋弧(hu)焊(han)
焊(han)(han)(han)(han)(han)件(jian)(jian)裝配時(shi)將同種不銹鋼管的墊(dian)板(ban)緊密地(di)貼在(zai)接(jie)(jie)頭下部(bu)(bu)用(yong)定位焊(han)(han)(han)(han)(han)固定,進行單面熔透焊(han)(han)(han)(han)(han)的一(yi)種埋弧焊(han)(han)(han)(han)(han)工藝。此時(shi)要(yao)求(qiu)墊(dian)板(ban)與(yu)焊(han)(han)(han)(han)(han)件(jian)(jian)之間的間隙不得超過0.5~1.0mm,否則液態(tai)金(jin)屬(shu)(shu)或熔渣必然從間隙處流出或嵌(qian)入夾縫中間而造(zao)成焊(han)(han)(han)(han)(han)接(jie)(jie)缺陷。焊(han)(han)(han)(han)(han)接(jie)(jie)完畢,墊(dian)板(ban)有一(yi)部(bu)(bu)分金(jin)屬(shu)(shu)被(bei)熔入焊(han)(han)(han)(han)(han)縫形成焊(han)(han)(han)(han)(han)縫金(jin)屬(shu)(shu),與(yu)焊(han)(han)(han)(han)(han)件(jian)(jian)牢固地(di)焊(han)(han)(han)(han)(han)在(zai)一(yi)起。故要(yao)求(qiu)墊(dian)板(ban)的化學(xue)成分、力學(xue)性(xing)能(neng)和耐腐蝕(shi)(shi)性(xing)能(neng)與(yu)焊(han)(han)(han)(han)(han)件(jian)(jian)相(xiang)同。永久墊(dian)板(ban)的尺寸見表4-21。永久墊(dian)板(ban)焊(han)(han)(han)(han)(han)接(jie)(jie)時(shi)的裝配示意圖如圖4-24所示。焊(han)(han)(han)(han)(han)接(jie)(jie)壓力容器封頭與(yu)筒(tong)體的環焊(han)(han)(han)(han)(han)縫時(shi),如果容器內部(bu)(bu)無法施焊(han)(han)(han)(han)(han),且不會(hui)引(yin)起縫隙腐蝕(shi)(shi)時(shi),可(ke)用(yong)永久墊(dian)板(ban)焊(han)(han)(han)(han)(han)接(jie)(jie)工藝。

③. 純銅墊埋弧焊
這(zhe)種(zhong)焊(han)接(jie)(jie)方法能使焊(han)接(jie)(jie)構件(jian)達到單面(mian)焊(han)背面(mian)成形的(de)(de)目的(de)(de)。純(chun)銅(tong)墊(dian)靠(kao)焊(han)接(jie)(jie)夾具緊貼待焊(han)接(jie)(jie)頭(tou)下面(mian),它與焊(han)件(jian)之間(jian)(jian)的(de)(de)間(jian)(jian)隙(xi)不允許大(da)于0.5mm,各種(zhong)形式的(de)(de)純(chun)銅(tong)墊(dian)結構如(ru)圖(tu)(tu)4-25所示,純(chun)銅(tong)墊(dian)板的(de)(de)形狀(zhuang)和(he)尺寸見圖(tu)(tu)4-26和(he)表4-22。在純(chun)銅(tong)墊(dian)接(jie)(jie)觸焊(han)件(jian)的(de)(de)一面(mian)開槽,槽的(de)(de)中心要(yao)與坡口根(gen)間(jian)(jian)隙(xi)對準,如(ru)果在槽內放焊(han)劑(ji)[見圖(tu)(tu)4-25(b)],則檀的(de)(de)寬(kuan)度和(he)深度都要(yao)相應地加寬(kuan)加深。


④. 鎖底對接接頭埋弧焊
這種焊(han)接(jie)方法適用(yong)于(yu)厚度大于(yu)10mm的(de)構件,常(chang)用(yong)在小直徑厚壁圓筒形(xing)焊(han)件的(de)環(huan)縫焊(han)接(jie),效果很好。鎖底(di)對接(jie)接(jie)頭見(jian)圖4-27。
⑤. 焊劑墊(dian)埋弧焊
這種焊(han)(han)(han)接(jie)(jie)方法也可使(shi)焊(han)(han)(han)件達到單面(mian)(mian)焊(han)(han)(han)背面(mian)(mian)成(cheng)(cheng)形(xing)的(de)(de)(de)目的(de)(de)(de)。根據焊(han)(han)(han)件厚(hou)度,在接(jie)(jie)縫下(xia)面(mian)(mian)墊上一層厚(hou)度為30~100mm的(de)(de)(de)焊(han)(han)(han)劑(ji),焊(han)(han)(han)劑(ji)下(xia)面(mian)(mian)是(shi)一層絕緣的(de)(de)(de)陶(tao)氈墊,陶(tao)氈墊下(xia)面(mian)(mian)是(shi)封閉的(de)(de)(de)橡(xiang)(xiang)膠管,如圖4-28所示。坡口根部與焊(han)(han)(han)劑(ji)墊中心(xin)要對中,當橡(xiang)(xiang)膠管一端(duan)通入(ru)壓縮(suo)空氣(qi)時(shi),焊(han)(han)(han)劑(ji)被均勻(yun)地(di)向上頂(ding)緊坡口的(de)(de)(de)根部。焊(han)(han)(han)接(jie)(jie)時(shi),電弧將熔透焊(han)(han)(han)件并(bing)熔化一些焊(han)(han)(han)劑(ji),形(xing)成(cheng)(cheng)單面(mian)(mian)焊(han)(han)(han)雙面(mian)(mian)成(cheng)(cheng)形(xing)的(de)(de)(de)焊(han)(han)(han)縫。假若焊(han)(han)(han)劑(ji)向上頂(ding)的(de)(de)(de)壓力過大或過小,在焊(han)(han)(han)縫背面(mian)(mian)會形(xing)成(cheng)(cheng)凹槽或突(tu)起部分(fen),嚴重者焊(han)(han)(han)縫不能(neng)成(cheng)(cheng)形(xing),焊(han)(han)(han)劑(ji)壓力對焊(han)(han)(han)縫成(cheng)(cheng)形(xing)的(de)(de)(de)影響見(jian)圖4-29。

⑥. 雙面對接埋弧焊
這是埋弧(hu)焊(han)(han)焊(han)(han)接對(dui)(dui)接焊(han)(han)縫(feng)的一(yi)種基本(ben)方法,使用(yong)(yong)最廣(guang)。大多數中(zhong)、厚板(ban)焊(han)(han)接時(shi)均使用(yong)(yong)雙面焊(han)(han)。這種焊(han)(han)接接頭(tou)的幾(ji)何連續(xu)性最好(hao),承載后(hou)應力狀態好(hao),能適應工作負荷(he)復雜和(he)苛(ke)刻的工作條件(jian)。故(gu)對(dui)(dui)焊(han)(han)縫(feng)長度(du)較(jiao)長,分布(bu)規則的焊(han)(han)縫(feng),應盡(jin)量采用(yong)(yong)這種施(shi)焊(han)(han)工藝方法。此時(shi)第(di)(di)一(yi)面施(shi)焊(han)(han)也不用(yong)(yong)任何形式襯(chen)墊,在(zai)無墊焊(han)(han)接時(shi),對(dui)(dui)焊(han)(han)件(jian)邊緣的準備和(he)裝配質量要(yao)求較(jiao)高(gao),希(xi)望坡口根部間(jian)隙為(wei)零,局部根部間(jian)隙不得超過1.0mm,否則液體金屬容易(yi)從間(jian)隙中(zhong)流出(chu)而燒穿(chuan)焊(han)(han)縫(feng)或(huo)形成焊(han)(han)瘤。為(wei)了有(you)一(yi)定的熔(rong)深(shen),同時(shi)又不至于焊(han)(han)穿(chuan),通常(chang)在(zai)第(di)(di)一(yi)面焊(han)(han)接時(shi),要(yao)求熔(rong)深(shen)為(wei)鋼(gang)板(ban)厚度(du)的60%~70%。如果被焊(han)(han)件(jian)較(jiao)薄(bo),在(zai)第(di)(di)一(yi)面焊(han)(han)接時(shi),可以采取減小焊(han)(han)接電流,提高(gao)焊(han)(han)接速(su)度(du)或(huo)者焊(han)(han)絲向后(hou)傾斜等措施(shi)來避(bi)免燒穿(chuan)。有(you)關奧(ao)氏體型(xing)不銹鋼(gang)中(zhong)等厚度(du)板(ban)材(cai)的無墊雙面埋弧(hu)焊(han)(han)的焊(han)(han)接參數見表(biao)4-23。


