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Analysis on Surface Crack of Steel Ball (II) ---- Raw material crack and Forged folding crack

    In the last article, we have introduced the Quenching crack, here we will introduce Raw material crack and Forged folding crack.
    1. Raw material crack
    Macroscopic morphology characteristics and location: the shapes and sizes of cracks are different, which are perpendicular to the ball equator along the rolling direction of the material.
    Microcosmic morphology characteristics: decarburization on the both sides of the cracks, mainly produced by oxide.
    Reasons: mixed with much nonmetal, too high heat temperature and cooled too fast after forging.
    Ways of analysis: use metallurgical microscope to observe the cracks and metallographic structure in two sides and use hot pickling process to make sure the morphology and location of the cracks.
    2. Forged folding crack
    Macroscopic morphology characteristics and location: arc shape, mainly in the poles of steel balls
    Microcosmic morphology characteristics: the tail of the profile of cracks is bald and show decarburization on the both sides of the cracks, mainly produced by the oxide.
    Reasons: cutting unevenly and improper application
    Ways of analysis: use metallurgical microscope to observe the cracks and metallographic structure in two sides and use hot pickling process to make sure the morphology and location of the cracks.