... annealing :heat to 740-760°c,keep 3-4h,furnace cold below 600°c,out and air cooling ,hardness ... temperature tempering :heat to 650-670°c,keep 2-3h,furnace cooling or air cooling ,hardness ≤187HBS.in order to ... so on.Production equipments:electric -hydraulic hammer,gas producer,reheating furnace,gas annealing furnace ,electric annealing furnace ,electric hydraulic grinding machine,electric band saw ...