Upper Bainite Formation Mechanism in Fe-1.36Si-1.01Cr-0.88C Steel

In this paper it is discussed on the mechanism of upper bainite formation. According to the results obtained in Fe-1.36Si-1.01Cr-0.88C steel, we discovered that the primary upper bainite is formed by subunits arranging along its long axis and steps are formed by subunits growing into different size along the thickness, the macro-plane of the primary upper bainite plate is the same as the basal plane (shear plane), the formation mechanism of the primary upper bainite plate is the nucleation-growth mechanism of subunits shearing one by one along long axis, controlled by diffusion.