普通低(di)(di)(di)(di)(di)合金(jin)鋼雖溫(wen)度(du)降低(di)(di)(di)(di)(di)強(qiang)度(du)有所增加，塑韌(ren)性(xing)卻急劇(ju)降低(di)(di)(di)(di)(di)，這類鋼不(bu)能(neng)用(yong)于(yu)(yu)低(di)(di)(di)(di)(di)溫(wen)下工(gong)作的(de)(de)結(jie)構上，而(er)低(di)(di)(di)(di)(di)溫(wen)用(yong)鋼在(zai)相應的(de)(de)低(di)(di)(di)(di)(di)溫(wen)條件下仍具有良(liang)好的(de)(de)韌(ren)性(xing)和(he)抗脆斷能(neng)力(li)，能(neng)夠確保結(jie)構的(de)(de)使用(yong)安全。低(di)(di)(di)(di)(di)溫(wen)鋼主要用(yong)于(yu)(yu)低(di)(di)(di)(di)(di)溫(wen)下工(gong)作的(de)(de)容(rong)器、管道(dao)和(he)結(jie)構，如(ru)石油化(hua)工(gong)設(she)備（化(hua)肥、乙烯、煤液化(hua)、液化(hua)石油氣等）、冷凍(dong)設(she)備、食(shi)品工(gong)業及液態(tai)氣體(ti)儲存設(she)備等。低(di)(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)(di)溫(wen)用(yong)鋼一(yi)般用(yong)于(yu)(yu)-110~-20℃工(gong)況條件。按適用(yong)溫(wen)度(du)范圍，低(di)(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)(di)溫(wen)用(yong)鋼可分為-40℃、-70℃、-90℃、-110℃鋼；按照鋼材的(de)(de)合金(jin)體(ti)系(xi)，低(di)(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)(di)溫(wen)用(yong)鋼可分為不(bu)含鎳及含鎳的(de)(de)兩大(da)類。不(bu)含鎳的(de)(de)低(di)(di)(di)(di)(di)溫(wen)用(yong)鋼一(yi)般工(gong)作溫(wen)度(du)在(zai)-40℃以(yi)(yi)上，而(er)含鎳的(de)(de)低(di)(di)(di)(di)(di)溫(wen)鋼根據鎳含量的(de)(de)高(gao)低(di)(di)(di)(di)(di)，可以(yi)(yi)工(gong)作在(zai)較低(di)(di)(di)(di)(di)的(de)(de)溫(wen)度(du)下，如(ru)2.5%Ni鋼可以(yi)(yi)用(yong)于(yu)(yu)-60℃以(yi)(yi)下，3.5%Ni鋼可以(yi)(yi)用(yong)于(yu)(yu)-110~-90℃。表1-10和(he)表1-11列出(chu)了我國常用(yong)低(di)(di)(di)(di)(di)合金(jin)低(di)(di)(di)(di)(di)溫(wen)壓力(li)容(rong)器用(yong)鋼的(de)(de)化(hua)學(xue)(xue)成分及力(li)學(xue)(xue)性(xing)能(neng)。

  低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)(wen)用(yong)鋼一般是(shi)(shi)通過合(he)金元(yuan)素的(de)固溶強化(hua)、晶粒(li)細(xi)化(hua)，并(bing)(bing)通過正火(huo)或(huo)正火(huo)＋回火(huo)處理細(xi)化(hua)組織晶粒(li)，從而獲得(de)良(liang)好的(de)低(di)(di)(di)溫(wen)(wen)(wen)韌性(xing)。在低(di)(di)(di)溫(wen)(wen)(wen)用(yong)鋼中(zhong)(zhong)常用(yong)合(he)金元(yuan)素是(shi)(shi)Mn、Ni、V、Nb等(deng)，如我(wo)國(guo)低(di)(di)(di)溫(wen)(wen)(wen)壓力(li)容器用(yong)鋼09Mn2VDR、15MnNiDR及(ji)09MnNiDR等(deng)，為保證低(di)(di)(di)溫(wen)(wen)(wen)韌性(xing)，在低(di)(di)(di)溫(wen)(wen)(wen)用(yong)鋼中(zhong)(zhong)盡量降低(di)(di)(di)碳(tan)含量，并(bing)(bing)嚴格控(kong)制硫、磷(lin)含量。低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)(wen)用(yong)鋼還有相應(ying)的(de)鑄件(jian)、鍛件(jian)及(ji)管(guan)材(cai)，JB4727-2000中(zhong)(zhong)對5種常用(yong)的(de)低(di)(di)(di)合(he)金低(di)(di)(di)溫(wen)(wen)(wen)鋼鍛件(jian)的(de)化(hua)學成(cheng)分、力(li)學性(xing)能做出(chu)了規定，見表(biao)1-12及(ji)表(biao)1-13所示。