普通低(di)(di)(di)(di)(di)合(he)(he)金鋼(gang)(gang)(gang)雖溫(wen)(wen)(wen)(wen)度(du)降(jiang)低(di)(di)(di)(di)(di)強(qiang)度(du)有(you)所增加(jia)，塑韌性(xing)卻急劇降(jiang)低(di)(di)(di)(di)(di)，這類鋼(gang)(gang)(gang)不(bu)能(neng)用(yong)(yong)(yong)(yong)(yong)于低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)下(xia)工作(zuo)(zuo)的(de)(de)(de)(de)(de)結構(gou)(gou)上，而(er)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)在相應(ying)的(de)(de)(de)(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)條(tiao)件(jian)下(xia)仍具有(you)良好的(de)(de)(de)(de)(de)韌性(xing)和抗脆(cui)斷能(neng)力(li)，能(neng)夠確(que)保結構(gou)(gou)的(de)(de)(de)(de)(de)使用(yong)(yong)(yong)(yong)(yong)安全。低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)主(zhu)要用(yong)(yong)(yong)(yong)(yong)于低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)下(xia)工作(zuo)(zuo)的(de)(de)(de)(de)(de)容器、管道和結構(gou)(gou)，如石油化(hua)工設備(bei)（化(hua)肥、乙烯、煤液化(hua)、液化(hua)石油氣等(deng)）、冷凍設備(bei)、食(shi)品工業及(ji)液態(tai)氣體儲存設備(bei)等(deng)。低(di)(di)(di)(di)(di)合(he)(he)金低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)一般(ban)用(yong)(yong)(yong)(yong)(yong)于-110~-20℃工況條(tiao)件(jian)。按適用(yong)(yong)(yong)(yong)(yong)溫(wen)(wen)(wen)(wen)度(du)范圍(wei)，低(di)(di)(di)(di)(di)合(he)(he)金低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)可(ke)分為(wei)-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)；按照鋼(gang)(gang)(gang)材的(de)(de)(de)(de)(de)合(he)(he)金體系，低(di)(di)(di)(di)(di)合(he)(he)金低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)可(ke)分為(wei)不(bu)含(han)(han)(han)鎳(nie)(nie)及(ji)含(han)(han)(han)鎳(nie)(nie)的(de)(de)(de)(de)(de)兩大類。不(bu)含(han)(han)(han)鎳(nie)(nie)的(de)(de)(de)(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)一般(ban)工作(zuo)(zuo)溫(wen)(wen)(wen)(wen)度(du)在-40℃以上，而(er)含(han)(han)(han)鎳(nie)(nie)的(de)(de)(de)(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)根據鎳(nie)(nie)含(han)(han)(han)量(liang)的(de)(de)(de)(de)(de)高低(di)(di)(di)(di)(di)，可(ke)以工作(zuo)(zuo)在較低(di)(di)(di)(di)(di)的(de)(de)(de)(de)(de)溫(wen)(wen)(wen)(wen)度(du)下(xia)，如2.5%Ni鋼(gang)(gang)(gang)可(ke)以用(yong)(yong)(yong)(yong)(yong)于-60℃以下(xia)，3.5%Ni鋼(gang)(gang)(gang)可(ke)以用(yong)(yong)(yong)(yong)(yong)于-110~-90℃。表(biao)1-10和表(biao)1-11列出(chu)了我國(guo)常用(yong)(yong)(yong)(yong)(yong)低(di)(di)(di)(di)(di)合(he)(he)金低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)壓力(li)容器用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)的(de)(de)(de)(de)(de)化(hua)學成(cheng)分及(ji)力(li)學性(xing)能(neng)。

  低(di)(di)(di)合(he)金(jin)低(di)(di)(di)溫(wen)用(yong)鋼一般是(shi)通過合(he)金(jin)元素的(de)固溶強(qiang)化(hua)、晶(jing)粒細化(hua)，并通過正火(huo)或正火(huo)＋回火(huo)處理細化(hua)組織(zhi)晶(jing)粒，從而獲得良(liang)好的(de)低(di)(di)(di)溫(wen)韌(ren)性(xing)。在低(di)(di)(di)溫(wen)用(yong)鋼中常用(yong)合(he)金(jin)元素是(shi)Mn、Ni、V、Nb等(deng)，如我國低(di)(di)(di)溫(wen)壓力容器用(yong)鋼09Mn2VDR、15MnNiDR及09MnNiDR等(deng)，為保證低(di)(di)(di)溫(wen)韌(ren)性(xing)，在低(di)(di)(di)溫(wen)用(yong)鋼中盡量(liang)降低(di)(di)(di)碳(tan)含量(liang)，并嚴格(ge)控制硫、磷含量(liang)。低(di)(di)(di)合(he)金(jin)低(di)(di)(di)溫(wen)用(yong)鋼還有相應的(de)鑄件、鍛件及管材，JB4727-2000中對5種常用(yong)的(de)低(di)(di)(di)合(he)金(jin)低(di)(di)(di)溫(wen)鋼鍛件的(de)化(hua)學成分、力學性(xing)能做(zuo)出了規(gui)定，見表1-12及表1-13所示(shi)。