1 Electric furnace,ladle refine,vacuum degassing and ESR method. 2.High purify. 1. Steel grade: GB 10Ni3MnCuAl/AISI P21/ ... : EF+LF+VD+ESR ,Hot Forged,Annealing,Normalizing,Tempering, Quenching and tempering,Solution,Aging,Slow Cooling;Black Surface or Grinding Surface ...