Q345B方管的開裂分析

　　在Q345B方管的(de)(de)(de)生(sheng)產過(guo)程(cheng)中(zhong),存在著冷(leng)作硬(ying)(ying)(ying)化(hua)和氫脆(cui)現(xian)(xian)象(xiang)(xiang),它(ta)們(men)是造成(cheng)Q345B方管開(kai)(kai)裂(lie)的(de)(de)(de)主要原(yuan)因。本文(wen)章(zhang)對兩(liang)個(ge)現(xian)(xian)象(xiang)(xiang)進行了(le)分析,提出了(le)一些防止冷(leng)拔(ba)小口徑無(wu)縫鋼(gang)(gang)管開(kai)(kai)裂(lie)的(de)(de)(de)措施(shi)。爆(bao)裂(lie)現(xian)(xian)象(xiang)(xiang)剖(pou)析Q345B方管是把直徑較小的(de)(de)(de)無(wu)縫鋼(gang)(gang)管通過(guo)拉(la)拔(ba)模(mo)具進行縮徑冷(leng)加工(gong)(gong)(gong)(gong)形(xing)(xing)(xing)成(cheng)的(de)(de)(de),其工(gong)(gong)(gong)(gong)藝路線(xian)一般為(wei)退火、酸(suan)洗、拉(la)拔(ba)。冷(leng)拔(ba)小口徑無(wu)縫鋼(gang)(gang)管在拉(la)拔(ba)過(guo)程(cheng)中(zhong),有時(shi)會(hui)出現(xian)(xian)從(cong)頭(tou)至尾(wei)象(xiang)(xiang)劈竹竿一樣迅速(su)開(kai)(kai)裂(lie)現(xian)(xian)象(xiang)(xiang),我們(men)把這(zhe)種現(xian)(xian)象(xiang)(xiang)統一稱之為(wei)開(kai)(kai)裂(lie)。影響(xiang)(xiang)(xiang)開(kai)(kai)裂(lie)的(de)(de)(de)原(yuan)因有:(1)加工(gong)(gong)(gong)(gong)硬(ying)(ying)(ying)化(hua);(2)氫脆(cui)現(xian)(xian)象(xiang)(xiang)。1.1加工(gong)(gong)(gong)(gong)硬(ying)(ying)(ying)化(hua)的(de)(de)(de)影響(xiang)(xiang)(xiang)鋼(gang)(gang)管在冷(leng)拔(ba)時(shi)產生(sheng)大量(liang)塑性(xing)變(bian)(bian)形(xing)(xing)(xing),引起明顯(xian)的(de)(de)(de)晶格畸變(bian)(bian),從(cong)而使晶格能(neng)(neng)量(liang)提高(gao)(gao),金(jin)屬(shu)內能(neng)(neng)增(zeng)加,導(dao)致金(jin)屬(shu)內部(bu)應(ying)(ying)(ying)力(li)不均勻,產生(sheng)殘(can)余(yu)內應(ying)(ying)(ying)力(li)。這(zhe)樣便(bian)使金(jin)屬(shu)硬(ying)(ying)(ying)度增(zeng)加,韌性(xing)下(xia)降(jiang)。金(jin)屬(shu)硬(ying)(ying)(ying)度越高(gao)(gao),冷(leng)拔(ba)時(shi)殘(can)余(yu)內應(ying)(ying)(ying)力(li)越大,加工(gong)(gong)(gong)(gong)硬(ying)(ying)(ying)化(hua)現(xian)(xian)象(xiang)(xiang)越明顯(xian)。當殘(can)余(yu)應(ying)(ying)(ying)力(li)達到(dao)一定數值時(shi),金(jin)屬(shu)就會(hui)沿(yan)某一列(lie)晶粒界面撕裂(lie),形(xing)(xing)(xing)成(cheng)鋼(gang)(gang)管的(de)(de)(de)開(kai)(kai)裂(lie)。1.2氫脆(cui)現(xian)(xian)象(xiang)(xiang)的(de)(de)(de)影響(xiang)(xiang)(xiang)在用(yong)酸(suan)液除氧化(hua)皮的(de)(de)(de)過(guo)程(cheng)中(zhong),硫酸(suan)和鐵發生(sheng)反應(ying)(ying)(ying)析出氫氣(qi)。氫以原(yuan)子(zi)或離子(zi)的(de)(de)(de)形(xing)(xing)(xing)式滲(shen)入(ru)鋼(gang)(gang)中(zhong),形(xing)(xing)(xing)成(cheng)固溶體。氫對鋼(gang)(gang)力(li)學(xue)性(xing)能(neng)(neng)的(de)(de)(de)影響(xiang)(xiang)(xiang)典型(xing)表(biao)現(xian)(xian)在氫脆(cui)現(xian)(xian)象(xiang)(xiang)上。