1. Whether the material can be quenched is related to the carbon content. High carbon content can be quenched directly, and low carbon content needs to be carburized to increase the carbon content of the quenched layer before quenching can be performed. Note: Quenching can only be done once! ! Because the structure of the material will change after quenching, forming a stable structure. Encountered high temperatures will cause the internal stress of the material to cause the material to break.

2. Nitriding is mainly used for surface treatment of special materials such as powder metallurgy or bearing steel to increase the surface hardness of the material, but the hardness is not comparable to that of quenching. However, due to the elemental stability of nitrogen, nitriding treatment is usually used when the surface requirements of the material are high and the hardness requirements are general.

3. Chrome plating is used for general surface treatment of materials, and its purpose is to prevent rust and increase aesthetics.

4. Since the carbon content of materials 35 and 45 is sufficient, no carburizing treatment is required, and quenching treatment can be performed directly. The maximum quenching temperature of material 35 can reach about 50HRC, and that of material 45 can reach above 55HRC. The quenching hardness of the same material is mainly determined by the tempering time and tempering temperature after quenching. The shorter the tempering time, the lower the tempering temperature and the higher the hardness after quenching. However, the higher the quenching hardness, the more brittle the material and the lower the toughness. So the choice of hardness is enough. If you need high hardness, you can use materials with high carbon content such as 65 and 70 materials or use materials containing Cr, such as 40Cr, 20CrMnTi, etc.