The slewing bearing material is usually use 50Mn 45# or 42CrMo. 

In order to facilitate processing, the material hardness is usually 220-260HB. 

This hardness is relatively soft for use and will wear out quickly. Just like a pair of shoes, the soles need to be wear-resistant. so they use rubber material. Therefore, in order to increase the wear resistance, it is necessary to quench the frequently contacted areas to increase the hardness. Normally, the bearing track and gear are quenched. Medium frequency quenching is usually used, with a hardness of 55-65HRC and a quenching layer depth of 3-5mm.