普通低(di)(di)(di)(di)(di)合(he)(he)金(jin)鋼(gang)(gang)(gang)雖溫(wen)(wen)(wen)度(du)降(jiang)低(di)(di)(di)(di)(di)強度(du)有所增(zeng)加，塑韌性(xing)卻(que)急劇降(jiang)低(di)(di)(di)(di)(di)，這類鋼(gang)(gang)(gang)不能用(yong)(yong)(yong)于(yu)(yu)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)下工(gong)作的(de)(de)結(jie)構(gou)上，而低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)在相應的(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)條件(jian)(jian)下仍(reng)具(ju)有良好的(de)(de)韌性(xing)和(he)抗脆斷能力(li)，能夠確保結(jie)構(gou)的(de)(de)使用(yong)(yong)(yong)安(an)全。低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)鋼(gang)(gang)(gang)主要用(yong)(yong)(yong)于(yu)(yu)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)下工(gong)作的(de)(de)容器(qi)、管道和(he)結(jie)構(gou)，如石油化(hua)(hua)工(gong)設(she)(she)備(bei)(bei)（化(hua)(hua)肥、乙烯、煤液化(hua)(hua)、液化(hua)(hua)石油氣等）、冷凍設(she)(she)備(bei)(bei)、食品工(gong)業及(ji)(ji)液態氣體儲存設(she)(she)備(bei)(bei)等。低(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)一(yi)般(ban)用(yong)(yong)(yong)于(yu)(yu)-110~-20℃工(gong)況條件(jian)(jian)。按(an)(an)適用(yong)(yong)(yong)溫(wen)(wen)(wen)度(du)范圍(wei)，低(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)可分為(wei)-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)；按(an)(an)照鋼(gang)(gang)(gang)材的(de)(de)合(he)(he)金(jin)體系，低(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)可分為(wei)不含鎳及(ji)(ji)含鎳的(de)(de)兩(liang)大類。不含鎳的(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)用(yong)(yong)(yong)鋼(gang)(gang)(gang)一(yi)般(ban)工(gong)作溫(wen)(wen)(wen)度(du)在-40℃以(yi)上，而含鎳的(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)鋼(gang)(gang)(gang)根據鎳含量的(de)(de)高低(di)(di)(di)(di)(di)，可以(yi)工(gong)作在較低(di)(di)(di)(di)(di)的(de)(de)溫(wen)(wen)(wen)度(du)下，如2.5%Ni鋼(gang)(gang)(gang)可以(yi)用(yong)(yong)(yong)于(yu)(yu)-60℃以(yi)下，3.5%Ni鋼(gang)(gang)(gang)可以(yi)用(yong)(yong)(yong)于(yu)(yu)-110~-90℃。表1-10和(he)表1-11列出(chu)了我國常用(yong)(yong)(yong)低(di)(di)(di)(di)(di)合(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)壓力(li)容器(qi)用(yong)(yong)(yong)鋼(gang)(gang)(gang)的(de)(de)化(hua)(hua)學(xue)成分及(ji)(ji)力(li)學(xue)性(xing)能。

  低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)用(yong)鋼一般是通過合金(jin)元素的(de)固(gu)溶強化、晶(jing)粒細(xi)化，并通過正(zheng)火(huo)或正(zheng)火(huo)＋回火(huo)處(chu)理細(xi)化組織(zhi)晶(jing)粒，從而(er)獲得良好的(de)低(di)(di)(di)溫(wen)韌性。在(zai)低(di)(di)(di)溫(wen)用(yong)鋼中(zhong)常用(yong)合金(jin)元素是Mn、Ni、V、Nb等，如我(wo)國低(di)(di)(di)溫(wen)壓力(li)容器(qi)用(yong)鋼09Mn2VDR、15MnNiDR及09MnNiDR等，為保證低(di)(di)(di)溫(wen)韌性，在(zai)低(di)(di)(di)溫(wen)用(yong)鋼中(zhong)盡量(liang)降低(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)用(yong)鋼還有相應的(de)鑄件(jian)、鍛(duan)件(jian)及管(guan)材，JB4727-2000中(zhong)對5種常用(yong)的(de)低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)鋼鍛(duan)件(jian)的(de)化學(xue)成分、力(li)學(xue)性能做出了規(gui)定(ding)，見表(biao)1-12及表(biao)1-13所示。