... hole centrifugal casting GHII3 nature hard after high temperatureMaterial of screw raw material The finished product processing requirements38CrMoAlA,SACM645,42CrMoNitriding treatment42CrMo ... -2.0mmScrew type:Gradual type, mutant type, wave type, barrier type, double screen type, shunt type, separation type, exhaust type, pin type, mixed type, double- head type, three-head type, multi head type etc ...