普通(tong)低(di)(di)(di)(di)(di)合(he)(he)(he)金(jin)鋼(gang)(gang)(gang)雖(sui)溫(wen)(wen)(wen)(wen)(wen)度(du)(du)降(jiang)低(di)(di)(di)(di)(di)強度(du)(du)有(you)所增(zeng)加，塑韌(ren)性(xing)卻(que)急劇降(jiang)低(di)(di)(di)(di)(di)，這類鋼(gang)(gang)(gang)不能(neng)用(yong)于(yu)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)下(xia)(xia)工(gong)(gong)(gong)作的(de)(de)(de)結構(gou)上(shang)，而低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)(gang)在相應(ying)的(de)(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)條件(jian)下(xia)(xia)仍具有(you)良好(hao)的(de)(de)(de)韌(ren)性(xing)和抗脆斷能(neng)力(li)，能(neng)夠確(que)保(bao)結構(gou)的(de)(de)(de)使(shi)用(yong)安全。低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)主要用(yong)于(yu)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)下(xia)(xia)工(gong)(gong)(gong)作的(de)(de)(de)容器、管(guan)道和結構(gou)，如(ru)石(shi)油(you)化(hua)工(gong)(gong)(gong)設備(bei)（化(hua)肥、乙烯、煤液(ye)(ye)化(hua)、液(ye)(ye)化(hua)石(shi)油(you)氣(qi)等）、冷凍設備(bei)、食(shi)品工(gong)(gong)(gong)業及液(ye)(ye)態氣(qi)體儲(chu)存設備(bei)等。低(di)(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)(gang)一般用(yong)于(yu)-110~-20℃工(gong)(gong)(gong)況(kuang)條件(jian)。按適(shi)用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)(du)范圍(wei)，低(di)(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)(gang)可分(fen)為-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)(gang)；按照鋼(gang)(gang)(gang)材的(de)(de)(de)合(he)(he)(he)金(jin)體系，低(di)(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)(gang)可分(fen)為不含鎳(nie)及含鎳(nie)的(de)(de)(de)兩(liang)大類。不含鎳(nie)的(de)(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)用(yong)鋼(gang)(gang)(gang)一般工(gong)(gong)(gong)作溫(wen)(wen)(wen)(wen)(wen)度(du)(du)在-40℃以(yi)上(shang)，而含鎳(nie)的(de)(de)(de)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)鋼(gang)(gang)(gang)根(gen)據鎳(nie)含量的(de)(de)(de)高低(di)(di)(di)(di)(di)，可以(yi)工(gong)(gong)(gong)作在較低(di)(di)(di)(di)(di)的(de)(de)(de)溫(wen)(wen)(wen)(wen)(wen)度(du)(du)下(xia)(xia)，如(ru)2.5%Ni鋼(gang)(gang)(gang)可以(yi)用(yong)于(yu)-60℃以(yi)下(xia)(xia)，3.5%Ni鋼(gang)(gang)(gang)可以(yi)用(yong)于(yu)-110~-90℃。表1-10和表1-11列出了我(wo)國常用(yong)低(di)(di)(di)(di)(di)合(he)(he)(he)金(jin)低(di)(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)(wen)壓力(li)容器用(yong)鋼(gang)(gang)(gang)的(de)(de)(de)化(hua)學成分(fen)及力(li)學性(xing)能(neng)。

  低(di)(di)(di)合金(jin)(jin)低(di)(di)(di)溫(wen)(wen)用鋼(gang)(gang)一般是通(tong)過合金(jin)(jin)元素(su)的固(gu)溶強化(hua)、晶(jing)粒(li)細化(hua)，并通(tong)過正火或正火＋回(hui)火處理細化(hua)組織(zhi)晶(jing)粒(li)，從而獲得(de)良好的低(di)(di)(di)溫(wen)(wen)韌性。在(zai)低(di)(di)(di)溫(wen)(wen)用鋼(gang)(gang)中常用合金(jin)(jin)元素(su)是Mn、Ni、V、Nb等，如我國低(di)(di)(di)溫(wen)(wen)壓力容器用鋼(gang)(gang)09Mn2VDR、15MnNiDR及09MnNiDR等，為保(bao)證低(di)(di)(di)溫(wen)(wen)韌性，在(zai)低(di)(di)(di)溫(wen)(wen)用鋼(gang)(gang)中盡(jin)量降低(di)(di)(di)碳含量，并嚴格控制硫(liu)、磷(lin)含量。低(di)(di)(di)合金(jin)(jin)低(di)(di)(di)溫(wen)(wen)用鋼(gang)(gang)還有相應的鑄件、鍛件及管材(cai)，JB4727-2000中對5種(zhong)常用的低(di)(di)(di)合金(jin)(jin)低(di)(di)(di)溫(wen)(wen)鋼(gang)(gang)鍛件的化(hua)學(xue)成分(fen)、力學(xue)性能做出了規定(ding)，見表1-12及表1-13所示。