The half shaft has two places with higher hardness, 1. bearing position 2. spline position. Simple quenching method. After about 4 minutes, depending on the thickness of the half shaft, pull out the natural temper. The same position is used for the bearing position, but the polishing allowance must be left. This quenching is to increase the surface hardness.

The half shaft is heat treated and corrected before the finishing. The semi-axle cannot pursue the hardness blindly. If it is too hard, it will be brittle. Generally, the blank is first tempered to achieve a certain hardness inside, and then the medium frequency quenching is performed to make the surface reach high hardness.

If the semi-axle is a forged blank without heat treatment, then it needs to be heat treated in a professional heat treatment plant (workshop) because the hardness of the surface and the inner part of the semi-axle is different, which requires both the hardness of the surface and the internal toughness. It is different to see the metallographic organization.

If the half-axis blank has been heat treated, there is no way to heat-treat again. The heat treatment will destroy the original metallographic structure, resulting in the change and decrease of the properties of the material. Simple annealing and re-quenching will not work. Strictly speaking, The annealed material needs to be forged, and then subjected to heat treatment such as quenching and quenching.

If the lathe processing after annealing is performed, the heat treatment (quenching) can no longer be performed, and the heat treatment causes deformation changes such as half-axis precision (bending) and surface roughness, and the accuracy level and requirements of the original processing cannot be achieved.