Longitudinal crack: along the longitudinal distribution of the workpiece, the crack is deep and long, for one or more. Reason: complete quenching, temperature rise, crack tendency increase, the size of the workpiece and complex shape is easy to produce longitudinal crack.Transverse crack: the crack is perpendicular to the axial direction, and the crack form diverges from the center to the surrounding, easy to grow in large size workpiece. Due to the difference between the inner and outer martensitic phase transitions, the phase transition stress is very large.Surface crack: reticulated and shallow. High frequency heating or flame quenching will result in rapid cooling until austenitizing temperature is reached.Spalling crack: after surface hardening or chemical heat treatment, spalling along the surface of the diffusion layer is called a glass crack. The cracks are parallel to the surface of the workpiece and lie beneath the surface.The microscopic characteristics of quenching cracks: in the polished state, they are serrate and straight, mainly along the crystal, but also along the crystal and mixed crystal. There is no decarbonization on either side of the crack, fracture, no oxidation color on the crack, and fracture along the crystal or mixed crystal is brittle.
Longitudinal crack: along the longitudinal distribution of the workpiece, the crack is deep and long, for one or more. Reason: complete quenching, temperature rise, crack tendency increase, the size of the workpiece and complex shape is easy to produce longitudinal crack.<br>Transverse crack: the crack is perpendicular to the axial direction, and the crack form diverges from the center to the surrounding, easy to grow in large size workpiece. Due to the difference between the inner and outer martensitic phase transitions, the phase transition stress is very large.<br>Surface crack: reticulated and shallow. High frequency heating or flame quenching will result in rapid cooling until austenitizing temperature is reached.<br>Spalling crack: after surface hardening or chemical heat treatment, spalling along the surface of the diffusion layer is called a glass crack. The cracks are parallel to the surface of the workpiece and lie beneath the surface.<br>The microscopic characteristics of quenching cracks: in the polished state, they are serrate and straight, mainly along the crystal, but also along the crystal and mixed crystal. There is no decarbonization on either side of the crack, fracture, no oxidation color on the crack, and fracture along the crystal or mixed crystal is brittle.
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