a106b在阀门中很少用，A105是锻件标准，A106-B是钢管牌号，这两种材料国内都生产。a106b 属于美标碳素钢，与中国20#钢差不多。化学成分：碳:<=0.3%锰:0.29%~1.06%磷:<=0.035%硫:<=0.035%硅:>=0.1%铬:<=0.40%铜:<=0.40%钼:<=0.15%镍:<=0.40%钒:<=0.08%
