Conical twin screw &barrel 1,Hardness After Hardending&Tempering : HB240~280 Technical Specification1,Hardness After Hardending&Tempering : HB240~2802,Nitrided Hardness : HV900~9503,Nitrided Case Depth : 0.55~0.7mm4,Nitrided Brittleness :Less Than Grade 15,Surface Roughness :Ra 0.46,Screw Straightness :0.015mm7,Surface Chromium-Plating’s Hardness After Nitriding≥900HB8,Chromium –plating Depth :0. ...