A3碳素结构钢旧钢号为Q235碳素结构钢 化学成份编辑Q235分A、B、C、D四级(GB/T 700-2006)Q235**含 C ≤0.22% Mn ≤1.4% Si ≤0.35% S ≤0.050% P ≤0.045%Q235B级含 C ≤0.20% Mn ≤1.4% Si ≤0.35% S ≤0.045% P ≤0.045%Q235C级含 C ≤0.17% Mn ≤1.4% Si ≤0.35% S ≤0.040 %P ≤0.040%Q235D级含 C ≤0.17% Mn ≤1.4% Si ≤0.35% S ≤0.035% P ≤0.035%