DIN 1630 ST44.4 seamless steel tube after heat treatment without tempering, hardness greater than HRC55 is qualified. The actual hardness is HRC55.
In the heat treatment of DIN 1630 ST44.4 seamless steel tube parts after tempering and tempering have good comprehensive mechanical properties, widely used in a variety of important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating loads. But DIN 1630 ST44.4 seamless steel tube surface hardness is low, not wear resistance.
The surface hardness of parts can be improved by quenching and tempering. DIN 1630 ST44.4 seamless steel tube in the heat treatment of carburizing treatment is generally used for surface wear resistance, core impact resistance of heavy duty parts, its wear resistance than quenching and tempering + surface high quenching.
The surface carbon content of DIN 1630 ST44.4 seamless steel tube is 0.8-1.2%, and the core is generally 0.1-0.25%. After heat treatment, the surface can obtain a high hardness, the core of low hardness, impact resistance.
