普通低(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)鋼(gang)(gang)(gang)(gang)(gang)雖溫(wen)(wen)度降(jiang)低(di)(di)(di)(di)(di)(di)強度有(you)所增加，塑韌性(xing)卻急劇降(jiang)低(di)(di)(di)(di)(di)(di)，這類鋼(gang)(gang)(gang)(gang)(gang)不(bu)能(neng)用(yong)(yong)于低(di)(di)(di)(di)(di)(di)溫(wen)(wen)下工(gong)作(zuo)(zuo)的(de)(de)結(jie)構上，而(er)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)用(yong)(yong)鋼(gang)(gang)(gang)(gang)(gang)在(zai)相應的(de)(de)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)條件(jian)下仍具有(you)良(liang)好(hao)的(de)(de)韌性(xing)和(he)抗脆斷能(neng)力，能(neng)夠確保結(jie)構的(de)(de)使用(yong)(yong)安全。低(di)(di)(di)(di)(di)(di)溫(wen)(wen)鋼(gang)(gang)(gang)(gang)(gang)主要用(yong)(yong)于低(di)(di)(di)(di)(di)(di)溫(wen)(wen)下工(gong)作(zuo)(zuo)的(de)(de)容(rong)器、管道(dao)和(he)結(jie)構，如石油化(hua)工(gong)設備（化(hua)肥(fei)、乙(yi)烯、煤液(ye)化(hua)、液(ye)化(hua)石油氣等(deng)）、冷凍設備、食品(pin)工(gong)業及(ji)液(ye)態氣體儲存設備等(deng)。低(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)用(yong)(yong)鋼(gang)(gang)(gang)(gang)(gang)一般用(yong)(yong)于-110~-20℃工(gong)況條件(jian)。按適用(yong)(yong)溫(wen)(wen)度范圍，低(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)用(yong)(yong)鋼(gang)(gang)(gang)(gang)(gang)可(ke)(ke)分(fen)為-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)(gang)(gang)；按照(zhao)鋼(gang)(gang)(gang)(gang)(gang)材的(de)(de)合(he)(he)金(jin)體系(xi)，低(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)用(yong)(yong)鋼(gang)(gang)(gang)(gang)(gang)可(ke)(ke)分(fen)為不(bu)含鎳(nie)及(ji)含鎳(nie)的(de)(de)兩大類。不(bu)含鎳(nie)的(de)(de)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)用(yong)(yong)鋼(gang)(gang)(gang)(gang)(gang)一般工(gong)作(zuo)(zuo)溫(wen)(wen)度在(zai)-40℃以(yi)(yi)上，而(er)含鎳(nie)的(de)(de)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)鋼(gang)(gang)(gang)(gang)(gang)根據(ju)鎳(nie)含量的(de)(de)高(gao)低(di)(di)(di)(di)(di)(di)，可(ke)(ke)以(yi)(yi)工(gong)作(zuo)(zuo)在(zai)較低(di)(di)(di)(di)(di)(di)的(de)(de)溫(wen)(wen)度下，如2.5%Ni鋼(gang)(gang)(gang)(gang)(gang)可(ke)(ke)以(yi)(yi)用(yong)(yong)于-60℃以(yi)(yi)下，3.5%Ni鋼(gang)(gang)(gang)(gang)(gang)可(ke)(ke)以(yi)(yi)用(yong)(yong)于-110~-90℃。表1-10和(he)表1-11列出了我國常用(yong)(yong)低(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)壓力容(rong)器用(yong)(yong)鋼(gang)(gang)(gang)(gang)(gang)的(de)(de)化(hua)學(xue)成分(fen)及(ji)力學(xue)性(xing)能(neng)。

  低(di)合(he)金低(di)溫(wen)用(yong)鋼(gang)(gang)一(yi)般是通過(guo)合(he)金元素(su)的固溶強(qiang)化(hua)(hua)(hua)、晶(jing)粒細化(hua)(hua)(hua)，并通過(guo)正火(huo)或正火(huo)＋回火(huo)處理細化(hua)(hua)(hua)組織(zhi)晶(jing)粒，從而獲得良(liang)好的低(di)溫(wen)韌性(xing)。在(zai)低(di)溫(wen)用(yong)鋼(gang)(gang)中(zhong)常用(yong)合(he)金元素(su)是Mn、Ni、V、Nb等(deng)，如我國低(di)溫(wen)壓力(li)容器用(yong)鋼(gang)(gang)09Mn2VDR、15MnNiDR及09MnNiDR等(deng)，為(wei)保證(zheng)低(di)溫(wen)韌性(xing)，在(zai)低(di)溫(wen)用(yong)鋼(gang)(gang)中(zhong)盡量(liang)降低(di)碳含量(liang)，并嚴格控(kong)制硫、磷含量(liang)。低(di)合(he)金低(di)溫(wen)用(yong)鋼(gang)(gang)還(huan)有相應的鑄件(jian)、鍛(duan)件(jian)及管材，JB4727-2000中(zhong)對5種常用(yong)的低(di)合(he)金低(di)溫(wen)鋼(gang)(gang)鍛(duan)件(jian)的化(hua)(hua)(hua)學成分、力(li)學性(xing)能(neng)做(zuo)出了規定，見表1-12及表1-13所示。