Stacking Fault Energy of Austenite Phase in Medium Manganese Steel
- PDF / 2,208,269 Bytes
- 16 Pages / 593.972 x 792 pts Page_size
- 15 Downloads / 235 Views
ON
IN recent years, medium manganese (Mn) steels (3 to 10 wt pct Mn)[1–3] under the category of third-generation advanced high-strength steels (3G-AHSSs) have drawn considerable research attention because of their improved mechanical properties, lower cost, and easy processing conditions. In such medium Mn steels, the microstructure consists of the face-centered cubic (fcc) austenite phase in an ultrafine martensite matrix.[1,4–7] An austenite reverted transformation[5,8–10] annealing technique is most frequently employed where the steel specimen with a fully martensitic structure is held at an intercritical annealing temperature for the partitioning
AVANISH K. CHANDAN, S.G. CHOWDHURY, and J. CHAKRABORTY are with the Materials Engineering Division, CSIR-National Metallurgical Laboratory, P.O.: Burmamines, Jamshedpur, Jharkhand 831007, India, and also with the Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India. Contact e-mail: [email protected] G. MISHRA and S. KUNDU are with the Research and Development Division, Tata Steel Limited, Jamshedpur 831007, India. B. MAHATO is with the Materials Engineering Division, CSIR-National Metallurgical Laboratory. Manuscript submitted September 13, 2019. Article published online July 26, 2019 METALLURGICAL AND MATERIALS TRANSACTIONS A
of solute alloying elements (C and Mn) in the austenite phase in order to stabilize it at room temperature. The partitioning phenomena leads to an increase in Mn level in the austenite phase that in turn can alter the stacking fault energy (SFE) of that austenite phase.[11] The plastic deformation of the austenite phase is primarily facilitated either by stacking faults through the martensitic transformation of the austenite phase via the transformation sequence c-austenite fi e-martensite fi amartensite or by twinning in such medium Mn steel. The former is the basic work hardening mechanism of the transformation-induced plasticity (TRIP),[12–18] and the latter is the basis for twinning-induced plasticity (TWIP).[15,16,19,20] These deformation pathways work harden the austenite phase during deformation.[14,15,19] Thus, the introduction of the austenite phase in the microstructure may improve both the strength and the ductility of the medium Mn steels. The deformation behavior of the austenite phase strongly depends on its SFE. It is well established that there exist different ranges of SFE values over which different deformation pathways are active; for instance, deformation-induced martensitic transformation is favored for SFE values < 18 to 20 mJ m2, whereas twinning is the major mode of plastic deformation along with the glide mechanism, for SFE values > 18 to 20 mJ m2.[21–26] Therefore, the
VOLUME 50A, OCTOBER 2019—4851
precise measurement of SFE of the austenite phase is essential to predict the possible deformation mechanism of the steel. To this end, X-ray diffraction (XRD) is a powerful tool for the determination of SFE, which requires precise determination of stacking fault probability (SFP) and the mean square st
Data Loading...
