Analysis of micro hardness mechanism of grinding surface of spiral bevel gear steel

In the process of meshing transmission of spiral bevel gear, the surfaces of two teeth often need to contact and bear great load. If the surface hardness is not enough, it will cause serious problems such as wear and cracking of spiral bevel gear. Therefore, it is very important to study the surface microhardness of spiral bevel gear steel 30crmnti after grinding.

This is because there are two factors affecting the surface hardening in the grinding of spiral bevel gear steel. One is the plastic deformation caused by grinding force, which will distort the lattice, elongate and even break the grains, which will improve the surface hardness of the workpiece after grinding. On the other hand, the grinding heat of spiral bevel gear steel will restore and recrystallize the plastic deformation, lose the work hardening, and form the softening effect. However, if the grinding zone temperature of spiral bevel gear steel is too high, which exceeds the phase transformation temperature of the material, the workpiece surface will undergo secondary quenching.

The micro hardness of grinding surface of spiral bevel gear steel is the result of the combined action of work hardening caused by plastic deformation and hardness change caused by grinding heat. On the one hand, the plastic deformation caused by grinding force in the grinding of spiral bevel gear steel causes dislocation movement, and the obstacle formed by the interaction of dislocations between various sliding systems causes dislocation accumulation, which greatly increases the deformation resistance and causes work hardening of the crystal. This strengthening phenomenon under the action of plastic deformation is called cold work hardening, which occurs below the softening temperature (i.e. recovery temperature or recrystallization temperature) of the material. On the other hand, the grinding heat of spiral bevel gear steel will restore and recrystallize the plastic deformation, lose the work hardening, and form the softening effect. However, if the grinding zone temperature of spiral bevel gear steel is too high and exceeds the phase transformation temperature of the material, the workpiece surface will undergo secondary quenching, the transformation from austenite to secondary quenched martensite will occur, and the surface microhardness will be improved.

Microhardness of the grinding surface of spiral bevel gear steel according to the material and grinding conditions of spiral bevel gear steel, there is no clear relationship between its hardness and the matrix, which needs to be analyzed in detail. This is also an important reason for us to carry out the experimental research on the surface microhardness of 30crmnti after grinding.

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