普通低(di)(di)(di)合(he)金鋼(gang)(gang)(gang)(gang)雖(sui)溫(wen)(wen)度(du)降(jiang)低(di)(di)(di)強度(du)有所增加，塑韌性(xing)卻(que)急劇降(jiang)低(di)(di)(di)，這類鋼(gang)(gang)(gang)(gang)不能(neng)用(yong)(yong)(yong)(yong)于低(di)(di)(di)溫(wen)(wen)下工(gong)(gong)(gong)作(zuo)的(de)(de)結構(gou)上，而(er)(er)低(di)(di)(di)溫(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)(gang)在相應(ying)的(de)(de)低(di)(di)(di)溫(wen)(wen)條(tiao)件下仍具(ju)有良好(hao)的(de)(de)韌性(xing)和抗脆斷能(neng)力，能(neng)夠確(que)保結構(gou)的(de)(de)使(shi)用(yong)(yong)(yong)(yong)安全。低(di)(di)(di)溫(wen)(wen)鋼(gang)(gang)(gang)(gang)主要(yao)用(yong)(yong)(yong)(yong)于低(di)(di)(di)溫(wen)(wen)下工(gong)(gong)(gong)作(zuo)的(de)(de)容器、管道(dao)和結構(gou)，如石油(you)化(hua)工(gong)(gong)(gong)設(she)(she)備（化(hua)肥、乙烯、煤(mei)液化(hua)、液化(hua)石油(you)氣(qi)等(deng)）、冷凍(dong)設(she)(she)備、食品(pin)工(gong)(gong)(gong)業及液態(tai)氣(qi)體儲存設(she)(she)備等(deng)。低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)(gang)一般用(yong)(yong)(yong)(yong)于-110~-20℃工(gong)(gong)(gong)況條(tiao)件。按適用(yong)(yong)(yong)(yong)溫(wen)(wen)度(du)范圍，低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)(gang)可(ke)分為-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)(gang)；按照鋼(gang)(gang)(gang)(gang)材的(de)(de)合(he)金體系，低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)(gang)可(ke)分為不含(han)(han)鎳(nie)(nie)(nie)及含(han)(han)鎳(nie)(nie)(nie)的(de)(de)兩大類。不含(han)(han)鎳(nie)(nie)(nie)的(de)(de)低(di)(di)(di)溫(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)(gang)一般工(gong)(gong)(gong)作(zuo)溫(wen)(wen)度(du)在-40℃以(yi)上，而(er)(er)含(han)(han)鎳(nie)(nie)(nie)的(de)(de)低(di)(di)(di)溫(wen)(wen)鋼(gang)(gang)(gang)(gang)根據(ju)鎳(nie)(nie)(nie)含(han)(han)量(liang)的(de)(de)高低(di)(di)(di)，可(ke)以(yi)工(gong)(gong)(gong)作(zuo)在較低(di)(di)(di)的(de)(de)溫(wen)(wen)度(du)下，如2.5%Ni鋼(gang)(gang)(gang)(gang)可(ke)以(yi)用(yong)(yong)(yong)(yong)于-60℃以(yi)下，3.5%Ni鋼(gang)(gang)(gang)(gang)可(ke)以(yi)用(yong)(yong)(yong)(yong)于-110~-90℃。表1-10和表1-11列出了我國常(chang)用(yong)(yong)(yong)(yong)低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)壓力容器用(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)(gang)的(de)(de)化(hua)學成分及力學性(xing)能(neng)。

  低(di)合(he)金低(di)溫(wen)用(yong)鋼一(yi)般是(shi)通過合(he)金元素的(de)固溶(rong)強化、晶粒(li)細(xi)化，并通過正(zheng)(zheng)火(huo)或正(zheng)(zheng)火(huo)＋回(hui)火(huo)處理細(xi)化組織晶粒(li)，從(cong)而獲得(de)良好的(de)低(di)溫(wen)韌性。在低(di)溫(wen)用(yong)鋼中(zhong)常用(yong)合(he)金元素是(shi)Mn、Ni、V、Nb等，如我國(guo)低(di)溫(wen)壓力容(rong)器(qi)用(yong)鋼09Mn2VDR、15MnNiDR及(ji)(ji)09MnNiDR等，為(wei)保證低(di)溫(wen)韌性，在低(di)溫(wen)用(yong)鋼中(zhong)盡量(liang)降低(di)碳含量(liang)，并嚴格控制硫、磷(lin)含量(liang)。低(di)合(he)金低(di)溫(wen)用(yong)鋼還有(you)相應的(de)鑄件(jian)、鍛(duan)件(jian)及(ji)(ji)管材，JB4727-2000中(zhong)對5種(zhong)常用(yong)的(de)低(di)合(he)金低(di)溫(wen)鋼鍛(duan)件(jian)的(de)化學成分、力學性能(neng)做出了規定(ding)，見表(biao)1-12及(ji)(ji)表(biao)1-13所(suo)示。