... -810°c,isothermal is 650-680°c,furnace cold below 500°c,out and air cooling,hardness after annealing ≤187HBS2.Partial annealing after ... annealing :heat to 740-760°c,keep 3-4h,furnace cold below ... 600°c,out and air cooling ,hardness after annealing ≤187HBS3.Nomalization:heat to ...