The pinning effect is useful for restraining austenite grain growth in low alloy steel and improving heat affected zone toughness in welded joints. We propose a new calculation model for predicting austenite grain growth behavior. The model is mainly comprised of two theories: the solute-drag effect and the pinning effect of TiN precipitates. The calculation of the solute-drag effect is based o...

In recent years, there has been a growing interest in steels of multi-phase structures, composed of a ferritic matrix, in which islets occur, that contain bainite-B, martensite-M and the untransformed austenite-A 1-9 . The multi-phase structure of steel with untransformed austenite promotes the increase of plasticity induced by the phase transformation – the TRIP effect 3-4, 6-8 . In steels con...

The stability of the retained austenite has been studied in situ in low-alloyed transformation-induced-plasticity (TRIP) steels using high-energy X-ray diffraction during tensile tests at variable temperatures down to 153 K. A detailed powder diffraction analysis has been performed to probe the austenite-to-martensite transformation by characterizing the evolution of the phase fraction, load pa...

Recent studies on TRIP-assisted multiphase steels have emphasised the drastic importance of the bainitic transformation in the optimisation of properties. Bainitic ageing is necessary for the stabilisation of austenite with respect to the martensitic transformation. This metastable retained austenite can still transform to martensite when plastically deformed (TRIP effect). The present work dea...

The redistribution of carbon after tempering of a novel nanocrystalline bainitic steel consisting of a mixture of supersaturated ferrite and retained austenite has been analyzed by atom probe tomography. No direct evidence supporting the additional carbon enrichment of austenite beyond that initially achieved during the bainite heat treatment was obtained during subsequent tempering of this hig...

Developing medium-Mn steels (MMnS) demands a better understanding of the microstructure evolution during thermo-mechanical treatments (TMTs). This study demonstrates relationship among processing, microstructure, and mechanical properties warm-rolled steel containing 1.5 wt. % Cu Ni. After short-time warm rolling (WR) in an intercritical temperature range, significant quantity (40.6 vol.%) aust...

High resolution synchrotron X–ray diffraction has been used to conduct in situ studies of the temporal evolution of phases during the isothermal growth of bainite. Two populations of austenitic material were identified: one corresponding to the initial austenite, the other to the carbon–enriched austenite associated with the bainitic ferrite. The observed lattice parameters and the asymmetry of...

The uniaxial thermomechanical behavior of a polycrystalline Fe-9%Cr-5%Ni-14%Mn-6%Si (all wt.%) shape memory alloy is investigated for both tensile and compressive stress states. The martensite start stresses measured upon tension and compression loading of austenite depend linearly on temperature, thus forming straight lines in the stress-temperature regime. The lines belonging to tension and c...

Austenite formation and its decomposition control the final microstructure and performance of steel welds. This paper presents an in-situ characterization of austenite formation and its decomposition in both the fusion zone (FZ) and heat-affected zone (HAZ) of an Fe-C-Al-Mn steel using time-resolved X-ray diffraction (TRXRD) with synchrotron radiation. Measurement of X-ray diffraction spectra a...