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Investigating on the reverse transformation of martensite to austenite and Pseudoelastic behavior in Ultrafine-Grained Fe-10Ni-7Mn (wt %) Steel processed by heavy cold rolling
Paper ID : 2094-UFGNSM13-FULL
Authors:
hamidreza koohdar *1, Mahmoud Nili-Ahmadabadi2, محمد حبیبی پارسا2, hadi ghasemi-nanesa3
1Tehran
2Center of Excellence for High Performance Materials, School of Metallurgy and Materials Engineering, University of Tehran, Tehran, Iran.
3School of Metallurgy and Materials Engineering, University of Tehran, Tehran, Iran.
Abstract:
Fe-10Ni-7Mn (wt. %) steel is a member of ultrahigh strength steels which shows good ductility in the solution annealed condition and excellent age hardenability. In the current research, this alloy was subjected to heavy cold rolling in which the reverse transformation of martensitic to austenite was brought about. From the XRD, DSC and dilatometric analyses, it is resulted that after 60 % cold rolling the austenite phase may be formed by displacive mechanism. Stability of austenite at room temperature is referred to the ultrafine/nano grain size of austenite after deformation which prevents the austenite to martensite transformation. The presence of ultrafine/nano austenite formed by displacive mechanism leads to the observation of new mechanical properties during cyclic tensile test. This behavior is known as pseudoelastic phenomenon. In this behavior, during loading-unloading tensile cycle, the shape of the specimen return to its original configuration with a hysteresis loop in its path to the zero strain point.
Keywords:
Fe-10Ni-7Mn (wt %) alloy; cold rolling; reverse transformation; pseudoelasticity.
Status : Paper Accepted (Oral Presentation)