At present, the commonly used screw materials in my country are No. 45 steel, 40Cr, ammoniated steel, 38CrMOAl, superalloy and so on.

1) No. 45 steel is cheap and has good processing performance, but poor wear resistance and corrosion resistance.
Heat treatment: quenched and tempered HB220-270, high frequency quenched HRC45--48.

2) The performance of 40Cr is better than that of No. 45 steel, but it is often plated with a layer of chromium to improve its corrosion resistance and wear resistance. However, the requirements for the chrome plating layer are relatively high. If the plating layer is too thin, it is easy to wear, and if it is too thick, it is easy to peel off. After peeling off, it will accelerate the corrosion, and it has been rarely used.

Heat treatment: quenched and tempered HB220-270, hard chrome plated HRC>55
3) Nitrided steel and 38CrMoAl have excellent comprehensive properties and are widely used. Typically the nitride layer is 0.4-0.6 mm. However, this material has low resistance to hydrogen chloride corrosion and is relatively expensive.

4) The superalloy material is superior to other materials. This material does not need coating and is mainly used for halogen-free screw of injection molding machine. The material has high oxidation resistance and corrosion resistance. Heat treatment hra55`60