Specific analysis of longitudinal cracks in cracks in ultrasonic quenching furnaces and complete sets of ultrasonic quenching equipment

① The macroscopic shape of the longitudinal crack of the ultrasonic quenching machine:

The crack is initiated along the surface of the slender part, and while expanding longitudinally, it expands to the inside of the section in the direction of the vertical surface, forming a wedge-shaped crack with an outer width and an inner tip. The extension of longitudinal crack always terminates near the center of the section. In appearance, the longitudinal single crack and the wedge-shaped crack on the cross section are the basic macroscopic form of longitudinal crack.

② The formation conditions of longitudinal cracks in the ultrasonic quenching machine:

Hardening is a necessary condition for the formation of longitudinal cracks. The stress state of the small workpiece after hardening belongs to the residual stress of the tissue stress type. In general, the tangential stress of the tissue stress is significantly larger than the axial stress. Therefore, the formation of structural stress-type residual stress is the stress condition for longitudinal cracks.