Equivalent Grades: GB 20CrMo, JIS SCM420, ASTM 4118, DIN 25CrMo4. SCM420 are alloy steel with high hardenability, temper brittleness, well weldability, less cold cracking tendency, good machinability, and great cold plastic strain. SCM420 generally are used for the parts which need high wear resistance, such as gears, shafts, high-pressure pipes, all kinds of fasteners, and so on.