... Treatmment;Quenching,Tempering,Annealing Close die forging,Hot Forging,die forging Forged,Forged Ring,Hot Forging,Close Die Forging 1) Material: Carbon steel, ... ) Production machine: Hot die forging presses,Friction press machine,Middle Frequency electric heater, Air hammer,Precision machining, and test facility5) ... couplers7) Manufacturer certification: ISO9001 (2000) / TS16949 close die forging