At present, China commonly used screw material 45 steel, 40Cr, ammoniated steel, 38CrMOAl, high temperature alloys.
（1）45 steel cheap, good processing performance, but 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 often to be coated with a layer of chromium, in order to improve its ability to resist corrosion and wear resistance. But the higher requirements of the chrome layer, the coating is too thin easy to wear, too thick is easy to peel off, but after the spill corrosion, has been less applied.Heat treatment: quenched and tempered HB220-270, hard chrome HRC> 55
（3） nitrided steel, 38CrMoAl comprehensive performance is relatively good, more widely used. General nitride layer of 0.4-0.6 mm. But this material is resistant to hydrogen chloride corrosion is low, and the price is higher.
（4）high temperature alloy material is superior to other materials, the material without plating, mainly used for injection molding machine halogen-free screw, the material anti-oxidation corrosion resistance, heat treatment hra55 `60.