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鍛(duan)造比對晶粒度的影響

文章來源：sjzwx 更新時間(jian)：2015-01-05 10:40:14

    如(ru)果鍛(duan)(duan)(duan)(duan)造(zao)(zao)比值合(he)(he)理，鋼(gang)(gang)錠經過高(gao)(gao)溫(wen)鍛(duan)(duan)(duan)(duan)造(zao)(zao)，破(po)碎了粗大的(de)(de)(de)初生(sheng)樹枝狀晶(jing)體(ti)；由于(yu)(yu)鋼(gang)(gang)的(de)(de)(de)高(gao)(gao)溫(wen)鍛(duan)(duan)(duan)(duan)造(zao)(zao)是在(zai)(zai)再(zai)結(jie)晶(jing)溫(wen)度(du)(du)(du)(du)以(yi)上進行的(de)(de)(de)，在(zai)(zai)此期(qi)間(jian)，發(fa)生(sheng)動(dong)態回復和(he)動(dong)態再(zai)結(jie)晶(jing)，產生(sheng)新的(de)(de)(de)較(jiao)細(xi)(xi)(xi)小(xiao)(xiao)的(de)(de)(de)晶(jing)粒(li)(li)(li)。鍛(duan)(duan)(duan)(duan)件(jian)的(de)(de)(de)晶(jing)粒(li)(li)(li)大小(xiao)(xiao)和(he)均(jun)(jun)勻(yun)性(xing)取決于(yu)(yu)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)溫(wen)度(du)(du)(du)(du)、變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)和(he)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)的(de)(de)(de)均(jun)(jun)勻(yun)性(xing)。在(zai)(zai)一定鍛(duan)(duan)(duan)(duan)造(zao)(zao)溫(wen)度(du)(du)(du)(du)下，存在(zai)(zai)著一個臨(lin)界(jie)(jie)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)范圍(wei)(wei)(wei)。鍛(duan)(duan)(duan)(duan)造(zao)(zao)時若實(shi)際發(fa)生(sheng)的(de)(de)(de)鍛(duan)(duan)(duan)(duan)造(zao)(zao)比值所(suo)表示的(de)(de)(de)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)處于(yu)(yu)該臨(lin)界(jie)(jie)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)范圍(wei)(wei)(wei)內，則(ze)鍛(duan)(duan)(duan)(duan)件(jian)再(zai)結(jie)晶(jing)后(hou)的(de)(de)(de)晶(jing)粒(li)(li)(li)比較(jiao)粗大。因(yin)此，只要變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)均(jun)(jun)勻(yun)，終(zhong)鍛(duan)(duan)(duan)(duan)溫(wen)度(du)(du)(du)(du)合(he)(he)適(shi)，特別是鍛(duan)(duan)(duan)(duan)坯(pi)在(zai)(zai)最(zui)后(hou)一火(huo)時實(shi)際達到的(de)(de)(de)鍛(duan)(duan)(duan)(duan)造(zao)(zao)比值合(he)(he)理，使(shi)其(qi)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)不(bu)(bu)在(zai)(zai)臨(lin)界(jie)(jie)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)范圍(wei)(wei)(wei)內，鍛(duan)(duan)(duan)(duan)件(jian)便能(neng)(neng)獲得均(jun)(jun)勻(yun)細(xi)(xi)(xi)小(xiao)(xiao)的(de)(de)(de)晶(jing)粒(li)(li)(li)組織(zhi)。如(ru)果把粗晶(jing)細(xi)(xi)(xi)化問(wen)題留給熱(re)處理工序(xu)解決，不(bu)(bu)但耗費(fei)工時，增加成本，而且(qie)對于(yu)(yu)某(mou)些(xie)從高(gao)(gao)溫(wen)冷卻至室溫(wen)時不(bu)(bu)發(fa)生(sheng)相變(bian)(bian)(bian)(bian)(bian)(bian)的(de)(de)(de)鋼(gang)(gang)種，如(ru)奧氏體(ti)型、鐵(tie)素體(ti)型不(bu)(bu)銹鋼(gang)(gang)和(he)耐熱(re)鋼(gang)(gang)鍛(duan)(duan)(duan)(duan)件(jian)，因(yin)不(bu)(bu)能(neng)(neng)通過熱(re)處理方法細(xi)(xi)(xi)化和(he)均(jun)(jun)勻(yun)晶(jing)粒(li)(li)(li)而無(wu)法實(shi)現，所(suo)以(yi)只能(neng)(neng)依靠合(he)(he)理的(de)(de)(de)鍛(duan)(duan)(duan)(duan)造(zao)(zao)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)工藝(yi)來達到細(xi)(xi)(xi)化和(he)均(jun)(jun)勻(yun)晶(jing)粒(li)(li)(li)的(de)(de)(de)目(mu)的(de)(de)(de)。在(zai)(zai)850—1200~的(de)(de)(de)鍛(duan)(duan)(duan)(duan)造(zao)(zao)溫(wen)度(du)(du)(du)(du)范圍(wei)(wei)(wei)內，鋼(gang)(gang)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)必須(xu)大于(yu)(yu)20％，才(cai)能(neng)(neng)使(shi)鍛(duan)(duan)(duan)(duan)件(jian)再(zai)結(jie)晶(jing)后(hou)獲得較(jiao)細(xi)(xi)(xi)小(xiao)(xiao)的(de)(de)(de)晶(jing)粒(li)(li)(li)。鋼(gang)(gang)在(zai)(zai)高(gao)(gao)溫(wen)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)時，變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)速(su)度(du)(du)(du)(du)慢的(de)(de)(de)其(qi)臨(lin)界(jie)(jie)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)程(cheng)(cheng)度(du)(du)(du)(du)范圍(wei)(wei)(wei)要大于(yu)(yu)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)速(su)度(du)(du)(du)(du)快的(de)(de)(de)鋼(gang)(gang)綜合(he)(he)一些(xie)實(shi)驗(yan)結(jie)果，碳素鋼(gang)(gang)和(he)合(he)(he)金鋼(gang)(gang)的(de)(de)(de)臨(lin)界(jie)(jie)變(bian)(bian)(bian)(bian)(bian)(bian)形(xing)(xing)(xing)范圍(wei)(wei)(wei)見表2。