普通低(di)(di)(di)(di)(di)(di)合(he)金鋼(gang)(gang)雖溫(wen)(wen)(wen)(wen)度降(jiang)低(di)(di)(di)(di)(di)(di)強度有(you)(you)所增加(jia)，塑韌性(xing)卻急劇(ju)降(jiang)低(di)(di)(di)(di)(di)(di)，這類(lei)(lei)鋼(gang)(gang)不能用(yong)于(yu)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)下工作(zuo)的(de)結(jie)構(gou)上，而低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)在相應的(de)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)條(tiao)件下仍具有(you)(you)良好的(de)韌性(xing)和(he)(he)抗脆斷能力，能夠確保結(jie)構(gou)的(de)使(shi)用(yong)安全。低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)鋼(gang)(gang)主要用(yong)于(yu)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)下工作(zuo)的(de)容器(qi)、管道和(he)(he)結(jie)構(gou)，如石(shi)油化(hua)工設(she)(she)備(bei)（化(hua)肥、乙烯、煤液(ye)化(hua)、液(ye)化(hua)石(shi)油氣等）、冷凍設(she)(she)備(bei)、食品工業(ye)及液(ye)態氣體儲存設(she)(she)備(bei)等。低(di)(di)(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)一般用(yong)于(yu)-110~-20℃工況(kuang)條(tiao)件。按(an)適(shi)用(yong)溫(wen)(wen)(wen)(wen)度范圍(wei)，低(di)(di)(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)可(ke)分為-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)；按(an)照鋼(gang)(gang)材(cai)的(de)合(he)金體系(xi)，低(di)(di)(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)可(ke)分為不含鎳及含鎳的(de)兩(liang)大類(lei)(lei)。不含鎳的(de)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)一般工作(zuo)溫(wen)(wen)(wen)(wen)度在-40℃以上，而含鎳的(de)低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)鋼(gang)(gang)根據鎳含量的(de)高低(di)(di)(di)(di)(di)(di)，可(ke)以工作(zuo)在較低(di)(di)(di)(di)(di)(di)的(de)溫(wen)(wen)(wen)(wen)度下，如2.5%Ni鋼(gang)(gang)可(ke)以用(yong)于(yu)-60℃以下，3.5%Ni鋼(gang)(gang)可(ke)以用(yong)于(yu)-110~-90℃。表1-10和(he)(he)表1-11列出了(le)我(wo)國(guo)常(chang)用(yong)低(di)(di)(di)(di)(di)(di)合(he)金低(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)壓力容器(qi)用(yong)鋼(gang)(gang)的(de)化(hua)學成分及力學性(xing)能。

  低(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)溫(wen)用鋼(gang)(gang)(gang)一般(ban)是(shi)通過(guo)(guo)合(he)(he)(he)金(jin)元素的固溶強化、晶粒細化，并(bing)通過(guo)(guo)正(zheng)火或(huo)正(zheng)火＋回火處理細化組(zu)織晶粒，從而獲得良好(hao)的低(di)(di)(di)(di)溫(wen)韌性。在低(di)(di)(di)(di)溫(wen)用鋼(gang)(gang)(gang)中(zhong)常用合(he)(he)(he)金(jin)元素是(shi)Mn、Ni、V、Nb等(deng)，如(ru)我國(guo)低(di)(di)(di)(di)溫(wen)壓力(li)容器用鋼(gang)(gang)(gang)09Mn2VDR、15MnNiDR及(ji)09MnNiDR等(deng)，為保(bao)證(zheng)低(di)(di)(di)(di)溫(wen)韌性，在低(di)(di)(di)(di)溫(wen)用鋼(gang)(gang)(gang)中(zhong)盡量(liang)降低(di)(di)(di)(di)碳含量(liang)，并(bing)嚴格(ge)控制硫、磷含量(liang)。低(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)溫(wen)用鋼(gang)(gang)(gang)還有相應(ying)的鑄件、鍛件及(ji)管(guan)材(cai)，JB4727-2000中(zhong)對5種常用的低(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)溫(wen)鋼(gang)(gang)(gang)鍛件的化學成分(fen)、力(li)學性能做出了規定，見表1-12及(ji)表1-13所示。