含Nb碳锰结构钢是含碳量在0.2％以下,铁索体和少珠光体型低合金钢(一般珠光体体积百分数在25％以下),珠光体每增加10％。抗拉强度可增加30N/mm~2左右,珠光体数量增多,使冲击转变温度升高,增加含碳量的结果,亦会使焊接性能变坏。根据Fe—Nb相图,Nb在rFe中固溶度,当1220℃时为1.2％(原子),在包晶温度989℃时,Nb在αFe中固溶度为1.1％ The Nb-containing carbon-manganese structural steels have a carbon content of less than 0.2%, ferrite bodies and less pearlite low alloy steels (generally less than 25% by volume of pearlite) and 10% increase of pearlite. Tensile strength can be increased by about 30N / mm ~ 2, pearlite increased the number of the impact transformation temperature increases, the result of increasing the carbon content will also make the welding performance deterioration. According to the Fe-Nb phase diagram, the solid solubility of Nb in rFe is 1.2% (atom) at 1220 ° C, the solid solubility of Nb in αFe at the peritectic temperature of 989 ° C is 1.1%