Critical Comparison of Novel and Conventional Processing for Dual-Phase Steels

The final properties of an industrial product depend on the processing route of the material. Hence there is an impetus to study different processing routes to obtain the most desirable final properties. In the present study, low carbon steels have been subjected to the novel deformation induced ferrite transformation (DIFT) technique to produce dual-phase microstructures that are composed of ultra-fine ferrite with martensite and/or bainite as a second transformation product. In this thermomechanical processing technique, the steels have been rapidly cooled from the austenitization temperature to the deformation temperature (which is at least 25°C above the Ar₃ temperature) to produce highly undercooled austenite, followed by heavy deformation, and subsequently rapidly cooled thereby facilitating transformation to fine grained ferrite. Comparing the final microstructures obtained by this route with those attained by conventional thermo-mechanical processing, it can be concluded that significant ferrite grain refinement is attainable by the novel DIFT technique thereby emphasizing its potential to achieve improved mechanical properties.