普(pu)通低(di)(di)(di)(di)合金(jin)鋼(gang)(gang)雖溫(wen)(wen)(wen)(wen)度(du)(du)降低(di)(di)(di)(di)強度(du)(du)有所增加，塑韌性卻急劇降低(di)(di)(di)(di)，這類鋼(gang)(gang)不能用(yong)(yong)(yong)(yong)于(yu)(yu)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)下(xia)工(gong)作的(de)(de)結構(gou)上，而(er)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)在相應的(de)(de)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)條件下(xia)仍具(ju)有良好的(de)(de)韌性和抗脆斷能力，能夠確保結構(gou)的(de)(de)使用(yong)(yong)(yong)(yong)安全。低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)鋼(gang)(gang)主要用(yong)(yong)(yong)(yong)于(yu)(yu)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)下(xia)工(gong)作的(de)(de)容(rong)器、管道和結構(gou)，如石油化工(gong)設備(bei)（化肥、乙(yi)烯、煤液化、液化石油氣等）、冷凍設備(bei)、食品工(gong)業及液態氣體儲存設備(bei)等。低(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)一(yi)般(ban)用(yong)(yong)(yong)(yong)于(yu)(yu)-110~-20℃工(gong)況(kuang)條件。按適(shi)用(yong)(yong)(yong)(yong)溫(wen)(wen)(wen)(wen)度(du)(du)范圍，低(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)可(ke)(ke)分為-40℃、-70℃、-90℃、-110℃鋼(gang)(gang)；按照(zhao)鋼(gang)(gang)材的(de)(de)合金(jin)體系，低(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)可(ke)(ke)分為不含鎳及含鎳的(de)(de)兩大(da)類。不含鎳的(de)(de)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)用(yong)(yong)(yong)(yong)鋼(gang)(gang)一(yi)般(ban)工(gong)作溫(wen)(wen)(wen)(wen)度(du)(du)在-40℃以(yi)(yi)(yi)上，而(er)含鎳的(de)(de)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)鋼(gang)(gang)根據(ju)鎳含量的(de)(de)高低(di)(di)(di)(di)，可(ke)(ke)以(yi)(yi)(yi)工(gong)作在較低(di)(di)(di)(di)的(de)(de)溫(wen)(wen)(wen)(wen)度(du)(du)下(xia)，如2.5%Ni鋼(gang)(gang)可(ke)(ke)以(yi)(yi)(yi)用(yong)(yong)(yong)(yong)于(yu)(yu)-60℃以(yi)(yi)(yi)下(xia)，3.5%Ni鋼(gang)(gang)可(ke)(ke)以(yi)(yi)(yi)用(yong)(yong)(yong)(yong)于(yu)(yu)-110~-90℃。表1-10和表1-11列出了我國常用(yong)(yong)(yong)(yong)低(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)溫(wen)(wen)(wen)(wen)壓力容(rong)器用(yong)(yong)(yong)(yong)鋼(gang)(gang)的(de)(de)化學(xue)成(cheng)分及力學(xue)性能。

  低(di)(di)合(he)(he)金(jin)低(di)(di)溫(wen)(wen)(wen)用(yong)鋼一般(ban)是通過合(he)(he)金(jin)元素(su)的(de)固(gu)溶強化(hua)、晶粒(li)細化(hua)，并(bing)(bing)通過正火或正火＋回火處理細化(hua)組織晶粒(li)，從而獲得良好的(de)低(di)(di)溫(wen)(wen)(wen)韌(ren)性。在(zai)低(di)(di)溫(wen)(wen)(wen)用(yong)鋼中常(chang)用(yong)合(he)(he)金(jin)元素(su)是Mn、Ni、V、Nb等(deng)，如(ru)我國低(di)(di)溫(wen)(wen)(wen)壓力容器用(yong)鋼09Mn2VDR、15MnNiDR及09MnNiDR等(deng)，為保證低(di)(di)溫(wen)(wen)(wen)韌(ren)性，在(zai)低(di)(di)溫(wen)(wen)(wen)用(yong)鋼中盡量(liang)(liang)降(jiang)低(di)(di)碳含量(liang)(liang)，并(bing)(bing)嚴(yan)格控制硫、磷含量(liang)(liang)。低(di)(di)合(he)(he)金(jin)低(di)(di)溫(wen)(wen)(wen)用(yong)鋼還有相應(ying)的(de)鑄件(jian)(jian)、鍛件(jian)(jian)及管材，JB4727-2000中對5種常(chang)用(yong)的(de)低(di)(di)合(he)(he)金(jin)低(di)(di)溫(wen)(wen)(wen)鋼鍛件(jian)(jian)的(de)化(hua)學成(cheng)分(fen)、力學性能做出了規定，見(jian)表(biao)1-12及表(biao)1-13所示(shi)。