The raw material includes 45# steel, 40Cr, ammoniated steel, 38CrMOAl, high temperature alloy, etc.

1. 45# steel is cheap, and has good processability, but the abrasion and corrosion resistant performances are poor.

Heat treatment: hardening and tempering - HB220—270, high-frequency quenching - HRC45--48.

2. The performance of the 40Cr is better than 45# steel, but it need to be plated with a layer of chromium to improve its abrasion and corrosion resistant capacities. And it has high requirements for the chromium coating. Thin coating is easy to wear, while thick coating is easy to peel off, which will speed corrosion. So it is now rarely used.

Heat treatment: hardening and tempering - HB220—270, hard chromium plating - HRC>55.

3. Ammoniated steel and 38CrMOAl have superior overall performances, so are widely used. Generally, the nitration case is 0.4 to 0.6 mm thick. But this material has poor performance in resisting hydrogen chloride corrosion, and the price is a little high.

4. High temperature alloy is better than other materials. It does not need coating, and is mainly used in injection molding machine halogen-free screws. This material has good performance in resisting oxidation and corrosion, the heat treatment is hra55`60.