普通(tong)低(di)(di)(di)(di)合(he)金鋼(gang)(gang)(gang)雖溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)降低(di)(di)(di)(di)強度(du)有所增加，塑韌(ren)性卻急劇降低(di)(di)(di)(di)，這類鋼(gang)(gang)(gang)不(bu)能(neng)用(yong)(yong)(yong)于(yu)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)下工(gong)(gong)作(zuo)的(de)(de)結(jie)(jie)構(gou)上，而(er)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)在相應的(de)(de)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)條件下仍具有良(liang)好的(de)(de)韌(ren)性和(he)抗(kang)脆斷能(neng)力，能(neng)夠確保結(jie)(jie)構(gou)的(de)(de)使(shi)用(yong)(yong)(yong)安全(quan)。低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)主(zhu)要用(yong)(yong)(yong)于(yu)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)下工(gong)(gong)作(zuo)的(de)(de)容(rong)器(qi)、管(guan)道和(he)結(jie)(jie)構(gou)，如石(shi)油化(hua)(hua)工(gong)(gong)設(she)備（化(hua)(hua)肥、乙烯、煤液(ye)化(hua)(hua)、液(ye)化(hua)(hua)石(shi)油氣(qi)等(deng)）、冷凍設(she)備、食品(pin)工(gong)(gong)業及液(ye)態(tai)氣(qi)體(ti)儲存(cun)設(she)備等(deng)。低(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)一般用(yong)(yong)(yong)于(yu)-110~-20℃工(gong)(gong)況條件。按適用(yong)(yong)(yong)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)范圍，低(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)可(ke)分(fen)為(wei)-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)；按照鋼(gang)(gang)(gang)材的(de)(de)合(he)金體(ti)系，低(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)可(ke)分(fen)為(wei)不(bu)含鎳(nie)及含鎳(nie)的(de)(de)兩大類。不(bu)含鎳(nie)的(de)(de)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)一般工(gong)(gong)作(zuo)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)在-40℃以(yi)(yi)上，而(er)含鎳(nie)的(de)(de)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)根據鎳(nie)含量(liang)的(de)(de)高低(di)(di)(di)(di)，可(ke)以(yi)(yi)工(gong)(gong)作(zuo)在較(jiao)低(di)(di)(di)(di)的(de)(de)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)下，如2.5%Ni鋼(gang)(gang)(gang)可(ke)以(yi)(yi)用(yong)(yong)(yong)于(yu)-60℃以(yi)(yi)下，3.5%Ni鋼(gang)(gang)(gang)可(ke)以(yi)(yi)用(yong)(yong)(yong)于(yu)-110~-90℃。表(biao)1-10和(he)表(biao)1-11列(lie)出了我(wo)國常用(yong)(yong)(yong)低(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)(wen)壓力容(rong)器(qi)用(yong)(yong)(yong)鋼(gang)(gang)(gang)的(de)(de)化(hua)(hua)學成分(fen)及力學性能(neng)。

  低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)(wen)(wen)用鋼(gang)一般是(shi)通(tong)過合金(jin)元(yuan)素的(de)(de)固溶(rong)強化(hua)、晶粒細化(hua)，并通(tong)過正火(huo)或(huo)正火(huo)＋回火(huo)處理細化(hua)組織晶粒，從而(er)獲得(de)良好(hao)的(de)(de)低(di)(di)(di)溫(wen)(wen)(wen)韌(ren)性。在(zai)低(di)(di)(di)溫(wen)(wen)(wen)用鋼(gang)中(zhong)常(chang)用合金(jin)元(yuan)素是(shi)Mn、Ni、V、Nb等(deng)，如我國低(di)(di)(di)溫(wen)(wen)(wen)壓力容器用鋼(gang)09Mn2VDR、15MnNiDR及(ji)09MnNiDR等(deng)，為保(bao)證低(di)(di)(di)溫(wen)(wen)(wen)韌(ren)性，在(zai)低(di)(di)(di)溫(wen)(wen)(wen)用鋼(gang)中(zhong)盡量(liang)降(jiang)低(di)(di)(di)碳含量(liang)，并嚴格控制硫、磷含量(liang)。低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)(wen)(wen)用鋼(gang)還有相(xiang)應(ying)的(de)(de)鑄件、鍛(duan)件及(ji)管材，JB4727-2000中(zhong)對5種常(chang)用的(de)(de)低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)(wen)(wen)鋼(gang)鍛(duan)件的(de)(de)化(hua)學成分(fen)、力學性能(neng)做出了規定，見表(biao)(biao)1-12及(ji)表(biao)(biao)1-13所示。