Depth of Nitrated Layer: 0.5-0.8mm Hardness of nitration: 900-1020Hv Fragility of nitration: Less than grade 1 Surface roughness: Ra 0.4um Hardness of Cr-coating Layer: ≥ 950Hv Thickness of Cr-coated Layer: 0.03-0.08mm Hardness of Bimetallic Layer: HRC55-72 Depth of Bimetallic Layer: >2mm We supply various types of screw barrel, always looking forward to your inquiry!