Reduce quenching and grinding cracks

In the production of railway and rolling mill bearings, due to the large size and heavy weight of the ferrule, the M structure is brittle during oil quenching. In order to obtain high hardness after quenching, strong cooling measures are often taken, resulting in quenching microcracks; During BL quenching, the toughness of BL structure is much better than that of M structure, and the compressive stress of -400~-500mpa is formed on the surface, which greatly reduces the tendency of quenching cracks; During grinding, the surface compressive stress counteracts part of the grinding stress, reduces the overall stress level, and greatly reduces the grinding cracks.