A generalized phase transformation kinetics model is used to understand the martensite to austenite transformation in a cold-rolled and annealed metastable AISI 301LN ultrafine-grained austenitic stainless steel. The model shows that the presence of interstitial nitrogen and heavy cold-rolling is important to promote fast transformation kinetics, through rapid nitrogen-diffusion and austenite n...

In situ neutron diffraction experiment was used during tensile testing at room temperature to examine the changes on the percentage and texture of both ferrite and austenite in a nanocrystalline bainitic steels transformed at two different temperatures 200°C and 300oC for different times to achieve the same phase percentages. Both samples showed an inadequate capability of austenite to transfor...

Local electron work function, adhesive force, modulus and deformation of ferrite and austenite phases in a duplex stainless steel were analyzed by scanning force microscopy. It is demonstrated that the austenite has a higher electron work function than the ferrite, corresponding to higher modulus, smaller deformation and larger adhesive force. Relevant first-principles calculations were conduct...

The combined influence of prior plastic strain in the austenite, and applied stress in the course of the transformation, on the crystallographic texture of a bainitic steel was studied in this work. The experimental data were obtained using Electron Back Scatter Diffraction (EBSD) method and analyzed using two methodologically different approaches. It was concluded that the plastic deformation ...

Coarse crystals of martensite can form by the coalescence of thin individual platelets of martensite under appropriate circumstances. Although these coarse grains are essentially single crystals, there exist significant orientation gradients across their dimensions. It is demonstrated that these gradients arise because of the plasticity induced in austenite due to the transformation strain asso...

The carbon concentration trapped in films of austenite between parallel platelets of bainite is often found to be much larger than that in the larger blocks of austenite between sheaves of bainite. The effect of this non-uniform distribution of carbon on the overall transformation kinetics of bainite is examined theoretically. It is found that the trapping of carbon in the films of austenite ac...

Recent research suggests that extraordinary combinations of strength and ductility can be achieved in the so–called δ–TRIP steels, which contain ferrite, bainite and austenite. A part of the reason for the ductility of almost 40% elongation at a strength of some 900MPa, is believed to be the optimal stability of the austenite to plastic deformation. We demonstrate here that mechanical stabilisa...

Lath martensite reveals a specific hierarchical subgrain structure, with laths, blocks and packets of particular crystallography. The presence of interlath retained austenite layers has been reported in the literature. This paper investigates the potential influence of the interlath retained austenite on the mechanical behaviour of lath martensite subgrains. To this purpose, a martensite grain ...

The present paper is concerned to the theoretical and experimental study of the growth kinetics of allotriomorphic ferrite in medium carbon vanadium-titanium microalloyed steel. A theoretical model is presented in this work to calculate the evolution of austenite-to-allotriomorphic ferrite transformation with time at a very wide temperature range. At temperatures above eutectoid temperature, wh...