The Development of Bearing Steels with Long Life and High Corrosion Resistance

摘要

The operating environments of rolling bearings are remarkably varied. With the use of bearings in various corrosive environments increasing, interest in stainless steel is growing. AISI 440C has been widely used in applications where corrosion resistance is of primary concern. However, its performance has not always been satisfactory because it contains coarse eutectic carbides that act as crack initiators under rolling contact stress and reduce Cr content in the martensitic matrix to the carbides. In response, we performed research to determine the most suitable bearing steel composition for both long fatigue life and noise performance and high corrosion resistance. Carbide size and hardness comparable to AISI 52100 steel were essential for the new stainless bearing steel(ESl), so we lowered the carbon and chromium contents and increased the nitrogen content of AISI440C. To control production costs, we applied conventional steelmaking processes for the nitrogen alloying. We evaluated the fatigue life and corrosion resistance of the new bearing steel(ESl). The new steel(ESl) outperformed conventional martensitic stainless steels in a tap water immersion test, a 5% aqueous sodium chloride immersion test, a saltwater spray test, noise level measuring test, water submerge life test, and oil lubrication life test.