At present, the screw materials commonly used in China are 45 steel, 40Cr, ammoniated steel, 38CrMOAl, high temperature alloy, and the like.
1) No. 45 steel is cheap, good processing performance, but poor wear and corrosion resistance. Heat treatment: quenched and tempered HB220-270, high frequency quenching HRC45--48.
2) The performance of 40Cr is better than that of 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, which has been less applied.
Heat treatment: quenched and tempered HB220-270, hard chrome plated HRC>553) nitrided steel, 38CrMoAl comprehensive performance is superior, 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.
3) 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.