The materials of ball bearings for FYH rolling bearings include steel for raceway rings (outer rings, inner rings) and rolling elements (balls), and steel plates for cages. These bearing materials should mainly have the following characteristics. (1) Due to the large local contact stress, the elastic limit is required to be high. (2) High rolling fatigue strength is required due to repeated exposure to large contact loads. (3) High hardness can be obtained (4) Good wear resistance (5) Good toughness against impact load (6) Good dimensional stability The body (ball) material generally uses the high carbon chromium bearing steel specified by JIS. In order to improve the reliability of the bearing, the high carbon chromium bearing steel has been subjected to vacuum degassing treatment, which reduces non-metallic impurities and oxygen content. For the above bearing materials, it is generally processed into the required shape first, and then through quenching and tempering treatment, the hardness is increased to about 60HRC before use. The chemical composition of FYH high carbon chromium bearing steel is shown in Table 12.1. FYH stainless steel series ball bearings (special symbol S6) are made of stainless steel with excellent corrosion resistance for the raceway rings and rolling elements. The material of the cage is cold-rolled steel sheet and steel strip specified by JIS. The chemical composition of cold-rolled steel sheets and strips is shown in Table 12.2. Materials of bearing housings The materials of bearing housings for rolling bearings with blocks are mainly grey iron castings, carbon steel castings and structural rolled steel, cold-rolled steel plates and steel strips. Gray cast iron has better vibration absorption properties than other materials, and various shapes can be easily obtained by casting. It has appropriate strength and good thermal performance. It is the most common material for bearing housings for rolling bearings with seats. The mechanical properties of gray iron castings are shown in Table 12.3. When high strength is required for bearing housings for FYH rolling bearings with blocks, carbon steel castings with high breaking strength and impact resistance or rolled steel for general structures are selected. Zinc alloy die-casting is used for the bearing housing of the purification series components, and stainless steel castings are used for the bearing housing of the stainless steel series components. In addition, cold-rolled steel sheets and steel strips are used as materials for the bearing housing for the steel sheet-made module. The mechanical properties of the above bearing housing materials are shown in Table 12.4 to Table 12.8. In addition to these materials, spheroidal graphite iron castings (FCD450-10 of JIS G5502) are sometimes used.