Q235A级含 C 0.14-0.22% Mn 0.30-0.65% Si ≤0.30% S ≤0.050 P ≤0.045。Q235B级含 C 0.12-0.20% Mn 0.30-0.70% Si ≤0.30% S ≤0.045 P ≤0.045（经需方同意，碳含量可不大于0.22%）。Q235C级含 C ≤0.18% Mn 0.35-0.80% Si ≤0.30% S ≤0.040 P ≤0.040。Q235D级含 C ≤0.17% Mn 0.35-0.80% Si ≤0.30% S ≤0.035 P ≤0.035。