1. Chemical compositionCodeKSJISAISIBSBSBSMaterialGradeSM30CS30C1030060A30080A30080M30C0.27~0.330.27~0.330.28~0.340.28~0.330.28~0.330.26~0.34Si0.15~0.350.15~0.35agreement0.10~0.400.10~0.40 -Mn0.60~0.900.60~0.900.60~0.900.50~0.700.70~0.900,60~1.00P≦0.030≦0.030≦0.040≦0.050≦0.050≦0.050S≦0.035≦0.035≦0.050≦0.050≦0.050≦0.050Ni -≦0.40≦0.40≦0.40Cr -≦0.30≦0.30≦0.30Mo- - -≦0.15≦0.15≦0.15Cu - - - -Remark..