Effect of Thermomechanical Processing on Ferrite Grain Size and Retained Austenite Morphology of Si-Mn TRIP steel

• First Author:Zicheng Zhang
• Journal:Metal Forming 2010
• Abstract:To study the effect of thermomechanical processing on ferrite grain size and retained austenite morphology in low carbon Si-Mn TRIP steel, the hot rolling process followed by a four-stages cooling process (Laminar Cooling-Air Cooling-Ultra-Fast Cooling-Asbestos-Heat-Preservation) was carried out using Fe-0.2C-1.44Si-1.32Mn steel. The steel microstructure possessing fine and uniform equiaxed ferrite grain with a size of 5 mu m in diameter as well as a high retained austenite volume fraction of more than 13.5% was obtained. The steel also exhibited a good balance of tensile strength with total elongation, e.g. 665 MPa and 41%. As a result, the lower finish rolling temperature, laminar cooling finish temperature and shorter air cooling time was found to lead to the refining of ferrite grain and changing of retained austenite morphology from film-like to granular shape. The latter was proved favourable to the plasticity of the steel.
• Key Words:Thermomechanical processing;TRIP steel;Retained austenite morphology;Si-Mn TRIP Steel;Ferrite grain
• Translation or Not:no