Specification: 15-250 L/D: 15/45 Material: 38CrMOALA Quenching and Tempering Hardness: HB240 ~280 Nitriding hardness: HV850~1000 Deepness of Nitriding: 0.45~0.7mm Nitriding Brittleness: Second Class Surface Roughness: Ra0.4 Screw Alignment: 0.015mm Hardness of Chrome Plating Coating after Nitrding≥900HV Thickness of Chrome Plating Coating: 0.05~0.10mm Hardness of Bimetallic Alloy: HRC56~65(nickel-base alloy) Alloy Deepness: 0.8~2.0mm