The semi-axle is an important part of the automotive transmission system. It is a solid shaft that transmits torque between the differential and the drive wheels. The inner end is generally connected to the half-shaft gear by a spline, and the outer end is connected to the hub by a flange. . The structural form of the automobile half shaft depends on the structure of the driving wheels. According to the force of the half shaft, the half shaft is divided into a full floating half shaft and a half floating half shaft. It can be seen that the automobile axle is an important part of the normal driving of the car. The performance of the axle is an important factor for the safe driving of the car.

Automobile axle shaft fracture type

Under the action of long-term torsional fatigue and impact forces, automobile half shafts are prone to bending, twisting and breaking, and spline teeth wear or skew, and other enemy obstacles. For semi-axial fractures, there are several types of morphology:

(1) Shedding or cracking of semi-axle blue disk

(2) Fracture of axle shaft

(3) Spiral fracture of axle shaft

(4) Mixed fractures and cracks on the axle shaft

(5) Fracture at the semi-axis spline

(6) Fractures and cracks of other morphologies of the semi-axis

Therefore, we first analyze the material selection of the semi-axis to find its cause and solution.

Material selection analysis of half shaft:

1) There are impurities in the material; observe the section with electronic instruments, there are many non-metallic impurities at the surface of the fracture, such as strip sulfides and spherical oxides. When the axle is subjected to torque, bending moment, force, etc. during normal driving, these impurities in the axle will make the strength, stiffness, elasticity and other properties of the axle shaft uneven. The place with impurities is easy to become the source of fatigue, which causes the source of fatigue to expand under the action of force, become cracks, and eventually break the semi-axis.

2) Material selection is incorrect

In the early days, medium carbon alloy steels such as 40MnB were used as materials for automotive axle shafts. After experimental analysis, it was found that the strength and hardness of these materials are low, especially the depth of the quenching layer is shallow and, with the radius, the depth of the quenching layer The difference is very large, so it is easy to cause problems such as poor performance and cracks in the shallow layer of the quenched layer when the shaft is under stress, which will cause the shaft to break.