Hemantha Kumar Yeddu

Reverse phase transformation of martensite to austenite in stainless steels: a 3D phase-field study

The martensitic transformation of austenite as well as the reversion of martensite to austenite has been reported to significantly improve mechanical properties of steels. In the present work, three dimensional (3D) elastoplastic phase-field simulations are performed to study the kinetics of martensite reversion in stainless steels at different annealing temperatures. The input simulation data are acquired from different sources, such as CALPHAD, ab initio calculations, and experiments. The results show that the reversion occurs both at the lath boundaries as well as within the martensitic laths, which is in good agreement with the experimental observations. The reversion that occurs within the laths leads to splitting of a single martensite lath into two laths, separated by austenite. The results indicate that the reversed austenite retains a large extent of plasticity inherited from martensite.

Martensitic Transformations in Steels : A 3D Phase-field Study

Martensite is considered to be the backbone of the high strength of many commercial steels. Martensite is formed by a rapid diffusionless phase transformation, which has been the subject of extensi ...

3D Phase Field Modeling of Martensitic Microstructure Evolution in Steels

Complex martensitic microstructure evolution in steels generates enormous curiosity among the materials scientists and especially among the Phase Field (PF) modeling enthusiasts. In the present work PF Microelasticity theory proposed by A.G. Khachaturyan coupled with plasticity is applied for modeling the Martensitic Transformation (MT) by using Finite Element Method (FEM). PF simulations in 3D are performed by considering different cases of MT occurring in a clamped system, i.e. simulation domain with fixed boundaries, of (a) pure elastic material with dilatation (b) pure elastic material without dilatation (c) elastic perfectly plastic material with dilatation having (i) isotropic as well as (ii) anisotropic elastic properties. As input data for the simulations the thermodynamic parameters corresponding to Fe - 0.3% C alloy as well as the physical parameters corresponding to steels acquired from experimental results are considered. The results indicate that elastic strain energy, dilatation and plasticity affect MT whereas anisotropy affects the microstructure.