At present, the screw materials commonly used in China are 45 steel, 40Cr, ammoniated steel, 38CrMOAl, and high temperature alloy.
1) No. 45 steel is cheap and has good processing performance, but has poor wear resistance and corrosion resistance. Heat treatment: quenched and tempered HB220-270, high frequency quenching HRC45--48.
2) 40Cr performance is better than 45 steel, but it is often coated with a layer of chromium to improve its corrosion resistance and wear resistance. However, the chrome plating layer is required to be high, the plating layer is too thin to be worn, and when it is too thick, it is easy to peel off, and the peeling is accelerated, and the corrosion is accelerated. Heat treatment: quenched and tempered HB220-270, hard chrome plated HRC>55.
3) Nitrided steel and 38CrMoAl have excellent comprehensive performance and are widely used. Generally, the nitrided layer is 0.4-0.6 mm. However, this material has low resistance to hydrogen chloride corrosion and is relatively expensive.
4) The high-temperature alloy material is superior to other materials. The material is not used for plating. It is mainly used for the production of halogen-free screw for injection molding machine. The material has high oxidation and corrosion resistance and heat treatment hra55`60.