Specification: Screw Diameter: ø15-ø300 aspect ratio: 15-46 product type: for different plastic products screw can be used: general type, pin type, barrier type, separation type, exhaust type, etc. . Substrate material: 1)38CrMoAlA (JIS SACM645)2)42CrMo (AISI 4140) process: heat treatment, nitriding treatment, technical parameters: nitriding depth: 0.50 mm-0.80 mm nitriding hardness: 900-1000 HV nitriding brittleness: & Lt; = Grade 1 Surface roughness: RA 0.4 screw straightness: 0.015 mm nitriding surface chromium plating hardness: ≥950 hv chromium plating thickness: 0.025-0.085 mm double alloy depth: 3 mm