Hardness of seamless steel pipe and hardness change after heat treatment

　　Hardness of seamless steel pipe and hardness change after heat treatment seamless steel pipe is made of high-quality carbon structural steel with low hardness and easy cutting. Cold Rolled Carbon Steel Seamless Steel Pipe is often used as template, pin, guide post, etc. in the mold, but it must be heat treated. Recommended heat treatment temperature: normalizing 850840, tempering 600.

　　If the hardness of seamless steel pipe is greater than HRC55 after quenching and before tempering, seamless steel pipe is qualified. The applied hardness is HRC55. The heat treatment process of carburizing and quenching shall not be adopted for 45 steel.

　　After quenching and tempering, the parts have good comprehensive mechanical properties and are widely used in all kinds of important structural parts, especially those connecting rods, bolts and gears working under alternating load, but the surface hardness is low and they are not wear-resistant. The surface hardness of parts can be improved by tempering + surface quenching.

　　Carburizing treatment is generally used for surface wear-resistant and core impact resistant heavy-duty parts, and its wear resistance is higher than quenching and tempering + surface quenching. The surface carbon content is 0.8-1.2%, and the core is generally 0.1-0.25% (0.35% in special cases). After heat treatment, high hardness can be obtained on the surface, low hardness on the core and impact resistance.