普(pu)通(tong)低(di)(di)(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)(jin)鋼(gang)(gang)(gang)雖(sui)溫(wen)(wen)(wen)(wen)(wen)度(du)降(jiang)低(di)(di)(di)(di)(di)(di)(di)(di)強(qiang)度(du)有(you)所增加，塑韌性(xing)卻急劇(ju)降(jiang)低(di)(di)(di)(di)(di)(di)(di)(di)，這(zhe)類鋼(gang)(gang)(gang)不(bu)(bu)(bu)能用(yong)(yong)(yong)(yong)(yong)于低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)下(xia)(xia)工作的(de)(de)結構(gou)上(shang)，而低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)在相(xiang)應(ying)的(de)(de)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)條(tiao)件下(xia)(xia)仍具有(you)良(liang)好的(de)(de)韌性(xing)和抗脆斷能力(li)，能夠確保結構(gou)的(de)(de)使用(yong)(yong)(yong)(yong)(yong)安全(quan)。低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)主(zhu)要用(yong)(yong)(yong)(yong)(yong)于低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)下(xia)(xia)工作的(de)(de)容器(qi)、管(guan)道和結構(gou)，如石油(you)化(hua)工設備（化(hua)肥、乙(yi)烯(xi)、煤(mei)液(ye)(ye)化(hua)、液(ye)(ye)化(hua)石油(you)氣等）、冷(leng)凍設備、食品工業及(ji)(ji)(ji)液(ye)(ye)態氣體(ti)儲存設備等。低(di)(di)(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)(jin)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(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。按(an)適用(yong)(yong)(yong)(yong)(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)范(fan)圍，低(di)(di)(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)(jin)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)可分(fen)(fen)為(wei)-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)；按(an)照鋼(gang)(gang)(gang)材的(de)(de)合(he)(he)金(jin)(jin)體(ti)系，低(di)(di)(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)(jin)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)可分(fen)(fen)為(wei)不(bu)(bu)(bu)含鎳及(ji)(ji)(ji)含鎳的(de)(de)兩大類。不(bu)(bu)(bu)含鎳的(de)(de)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)一般(ban)工作溫(wen)(wen)(wen)(wen)(wen)度(du)在-40℃以(yi)上(shang)，而含鎳的(de)(de)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)根(gen)據(ju)鎳含量(liang)的(de)(de)高低(di)(di)(di)(di)(di)(di)(di)(di)，可以(yi)工作在較低(di)(di)(di)(di)(di)(di)(di)(di)的(de)(de)溫(wen)(wen)(wen)(wen)(wen)度(du)下(xia)(xia)，如2.5%Ni鋼(gang)(gang)(gang)可以(yi)用(yong)(yong)(yong)(yong)(yong)于-60℃以(yi)下(xia)(xia)，3.5%Ni鋼(gang)(gang)(gang)可以(yi)用(yong)(yong)(yong)(yong)(yong)于-110~-90℃。表1-10和表1-11列(lie)出了我(wo)國常用(yong)(yong)(yong)(yong)(yong)低(di)(di)(di)(di)(di)(di)(di)(di)合(he)(he)金(jin)(jin)低(di)(di)(di)(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)壓(ya)力(li)容器(qi)用(yong)(yong)(yong)(yong)(yong)鋼(gang)(gang)(gang)的(de)(de)化(hua)學成分(fen)(fen)及(ji)(ji)(ji)力(li)學性(xing)能。

  低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)一般是通(tong)過合金(jin)元素的(de)固溶強化(hua)、晶粒細(xi)化(hua)，并(bing)通(tong)過正(zheng)火(huo)或正(zheng)火(huo)＋回(hui)火(huo)處(chu)理細(xi)化(hua)組(zu)織(zhi)晶粒，從而獲得(de)良好的(de)低(di)(di)(di)溫(wen)(wen)(wen)(wen)韌性(xing)。在低(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)中(zhong)常用(yong)合金(jin)元素是Mn、Ni、V、Nb等，如我國低(di)(di)(di)溫(wen)(wen)(wen)(wen)壓力容器用(yong)鋼(gang)09Mn2VDR、15MnNiDR及(ji)09MnNiDR等，為(wei)保證低(di)(di)(di)溫(wen)(wen)(wen)(wen)韌性(xing)，在低(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)中(zhong)盡量(liang)(liang)降低(di)(di)(di)碳含量(liang)(liang)，并(bing)嚴格控(kong)制硫、磷含量(liang)(liang)。低(di)(di)(di)合金(jin)低(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)鋼(gang)還有相(xiang)應的(de)鑄件(jian)(jian)、鍛件(jian)(jian)及(ji)管材，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)(wen)(wen)(wen)鋼(gang)鍛件(jian)(jian)的(de)化(hua)學(xue)成分、力學(xue)性(xing)能做(zuo)出了(le)規定，見表(biao)1-12及(ji)表(biao)1-13所示。