... size: 35/75, 45/90, 45/100, 50/105, 55/110, 60/125, 80/143, 80/156, 92/188, 95/188Material ... quality alloy steelTechnology: nitriding treatment, alloy coating spraying, heating treatment, screw fully hardeningDiameter: Φ45-Φ200(according to the demands of customers ... nitrition: less than grade 1Surface roughness: Ra 0.4umStreightness of screw: 0.015mmSurface of hardness of nitrated Cr coating layer: ≥ ...