Commonly used screw 45th steel, 40Cr, nitriding steel 38CrMOAl high temperature alloy
1) 45th steel cheaper, good processing properties, corrosion resistant properties.
Heat: Quenched and tempered HB220-270, high-frequency quenching HRC45--48
2) performance is superior to the 45th steel 40Cr, but tend to be coated with a layer of chromium, to improve its corrosion resistance and wear resistance capabilities. But requires high chromium plating, coating too thin and easy to wear, is too thick and easy to peel, flake to it accelerated corrosion, have less application.
Heat: Quenched and tempered HB220-270, hard chromium plated HRC>55
3) of nitrided steel 38CrMoAl excellent comprehensive properties, widely used. Nitride layer 0. 4-0. 6 mm. But this material's ability to resist the corrosion of hydrogen chloride is low, and the price is higher.
4) high temperature alloy is superior to other materials, the materials without coating, mainly used for halogen-free screw injection molding machine, high oxidation resistance and corrosion resistance of the material properties, heat treatment hra55'60.