Aluminum Double Spindle 1605 Rolled

For example, during quenching and rapid cooling of forgings, because the surface layer is first cooled to another point, the surface layer changes from austenite to martensite, and the volume swells, but the core is still in austenite state, preventing the surface layer from swelling, so the forging The core is under tensile stress and the surface is under compressive stress; when cooling continues, the temperature of the surface decreases and no longer swells. As the core is transformed into martensite, the volume will continue to expand. Therefore, it will be blocked by the surface. The part is subjected to compressive stress, and the surface layer is subjected to tensile stress. After cooling and forming, this stress still exists inside the forging and becomes a residual stress.

Therefore, during the quenching and cooling process, the changes of thermal stress and phase transformation stress are opposite, and the two residual stresses in the forging are also opposite. The combined stress of thermal stress and phase transformation stress is called quenching internal stress. When this residual internal stress inside the forging exceeds the yield point of the steel, it will cause plastic deformation of the workpiece, which will cause distortion of the forging.

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