20#無縫方矩管力學(xué)性能
碳 C :0.17%~0.2% 硅 Si:0.17%~0.37% 錳 Mn:0.35%~0.65% 硫 S :≤0.035% 磷 P :≤0.035% 鉻 Cr:≤0.25% 鎳 Ni:≤0.25% 銅 Cu:≤0.25%