The decomposition of austenite to ferrite or cementite begins at the equilibrium phase boundary of austenite/ (ferrite austenite) or austenite/(cementite austenite) in binary Fe–C phase diagram. The temperature values on the phase boundaries of austenite/(ferrite austenite) and austenite/(cementite austenite) at a certain carbon content are called Ae3 and Acm temperatures of the steel, respecti...

The microstructural evolution of Fe–0.2C–5Mn steel during intercritical annealing with holding time for up to 144 hours was examined by TEM and STEM. It was demonstrated by TEM that the martensite lath structure gradually transformed into a lamellar ferrite and austenite duplex structure. The partitioning of manganese from ferrite to austenite was found by STEM. Typical Kurdjumov-Sachs orientat...

This study investigated the microstructures of pearlite and martensite transformed from ultrafine-grained austenite in 0.45C steel and Vadded 0.45C steel. The mean prior austenite grain sizes were refined to be 4.5 μm in the 0.45C specimen and 2.4 μm in the V-added 0.45C specimen through cyclic heat treatment of austenitizing and water quenching, i.e., repetition of martensite § austenite trans...

The effect of different austenite grain size and different cooling rates on the austenite to ferrite transformation temperature and different ferrite morphologies in one Nb-microalloyed (HSLA) steel has been investigated. Three different austenite grain sizes were selected and cooled at two different cooling rates for obtaining austenite to ferrite transformation temperature. Moreover, samples ...

Abstract: transformation temperature and different ferrite morphologies in one Nb-microalloyed (HSLA) steel has beeninvestigated. Three different austenite grain sizes were selected and cooled at two different cooling rates for obtainingaustenite to ferrite transformation temperature. Moreover, samples with specific austenite grain size have beenquenched, partially, for investigation on the mic...

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...