Development of ultrafine bainite + martensite duplex microstructure in SAE 52100 bearing steel by prior cold deformation

摘要

We explore microstructural refinement through complete/partial recrystallization of prior cold-deformed ferrite during austen-itizing or austempering of SAE 52100 steel to obtain ultrafine bainite and martensite. Optical and scanning/transmission electron microscopy coupled with compositional microanalysis were employed to determine the volume fraction and dimension (thickness/ length) of ferritic sheaves and carbides. Characterization of mechanical properties indicates that 5-15 percent cold deformation significantly enhances the impact strength (approx 72 J) with marginal improvement in hardness and tensile strength over that in the unde-formed condition.