For large load to withstand the railway, rolling mill bearings, quenched by M after the main failure mode is used: When the inner sheath cracking, the outer wall of the outer wall of the block during use, the inner ring fragmentation, and austempered bearings Due to good impact toughness and surface compressive stress, no matter whether the inner sleeve is cracked during assembling or the outer sleeve is blocked off during use, the propensity of the inner sleeve is greatly reduced and the stress concentration on the edge of the roller can be reduced. Therefore, after quenching after quenching than M, the average life expectancy and reliability increase.