1.iron alloy , 1500 hour 2.hardness: 140HB-260HB 3.competitive price 4.strict QC system, stable quality. Hydraulic pressure and pneumatic parts field: valve,fairlead,gear wheel and piston;Machine tol parts: sea saw,guiding rail,worktable and transmission gear;Metallurgy machine parts: the transporting roller for the high-speed wire rolling mill;Refrigerator compressor parts:piston ring and ...