化学成分:S≤0.035
磷P≤0.035
铬Cr≤0.25
镍Ni≤0.25
铜Cu≤0.25
20g材质含碳量约0.05%~0.70%,个别可高达0.90%。可分为普通20g碳素结构钢和优质20g碳素结构钢两类