HOSSEINI Seyed Mohammad Kazem Imam Khomeini International University

Spoluautoři ZAREI-HANZAKI Abbass, YUE Steve

The outstanding balance of strength-ductility exhibited in newly-developed low silicon content TRIP-assisted steels can be achieved through precise controlling of microstructures which are composed of allotrimorphic ferrite, bainitic ferrite, retained austenite, and martensite. Ferrite as the first transformation product of austenite decomposition during cooling stage of any TMP processing has a profound effect on microstructural characteristics of subsequent transformation products and, hence, on resulted mechanical properties. In this study, a typical multi-stage TMP program was simulated in laboratory by using an automated hot-compression machine and the effects of ferrite grain size and its fraction on microstrucuural characteristics of subsequent austenite transformation products were investigated. Microstructure of samples were characterized by optical and electron microscopy, XRD, and Mössbauer spectroscopy. The results have shown that by increasing the amount of ferrite, retained austenite volume fraction, after a slight plateau, decreases. Ferrite grain refinement has also found to not only increase retained austenite fraction but also changes particle morphology to the desired type of interlath film-like.

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