Modeling the effect of prior austenite grain size on bainite formation kinetics

While experiments show that refining the prior austenite grain size can either accelerate or decelerate bainite formation in steels, kinetic models based on the successive nucleation of bainitic ferrite subunits can only predict an acceleration. In this work we develop a physically-based model for bainite kinetics assuming a displacive growth...

In situ TEM observations of the growth of bainitic ferrite in an Fe-0.3C-3Mn-1.5Si-0.15Mo steel

The current study reports in situ TEM observations of the growth of bainitic ferrite in an Fe-0.3C-3Mn-1.5Si-0.15Mo steel held isothermally at 300 °C with a higher spatio-temporal resolution than in previous studies. Significant variations were found in the lengthening rate, with the highest being in excess of 30,000 nm.s⁻¹ while...

Microstructure of vanadium micro-alloyed steels for automotive applications: Interaction of precipitation with austenite-to-ferrite phase transformation studied by SANS and neutron diffraction

The focus of the present work is on the micro-alloying element vanadium, which is well known for providing precipitation strengthening to steels and which has, therefore, attracted a lot of interest the last decades. Vanadium carbide precipitation can take place in the migrating austenite/ferrite interface during the austenite-to-ferrite phase...

Effect of the initial microstructure and thermal path on the final microstructure and bendability of a high strength ferrite-martensite dual phase steel

The combined effects of the initial microstructure and heating rate on ferrite recrystallization, austenite formation and transformation kinetics of a regular ferrite-martensite dual phase steel are investigated. Special attention is given to the effect of the martensite distribution on mechanical properties, particularly the bendability....

The role of the austenite grain size in the martensitic transformation in low carbon steels

There is sufficient experimental evidence to propose that the formation kinetics of athermal martensite directly depends on the austenite grain structure from which the martensite forms. Yet, this dependence is frequently ignored. The present study investigates the role of the prior austenite grain size (PAGS) in the martensitic...

Interaction of precipitation with austenite-to-ferrite phase transformation in vanadium micro-alloyed steels

The precipitation kinetics of vanadium carbides and its interaction with the austenite-to-ferrite phase transformation is studied in two micro-alloyed steels that differ in vanadium and carbon concentrations by a factor of two, but have the same vanadium-to-carbon atomic ratio of 1:1. Dilatometry is used for heat-treating the specimens and...

Revealing operando transformation dynamics in individual Li-ion electrode crystallites using X-Ray Microbeam Diffraction

For the development of next-generation batteries it is important to understand the structural changes in electrodes under realistic non-equilibrium conditions. With microbeam X-ray diffraction it is possible to probe many individual electrode grains concurrently under non-equilibrium conditions in realistic battery systems. This makes it...

Effect of Prior Athermal Martensite on the Bainite Transformation Kinetics for a Medium Carbon Steel

Bainitic steels have a right combination of strength and toughness when compared to that of martensitic and pearlitic steels. For the same reason, it is becoming a popular kind of steel among the automobile industry. It is important to study the bainite transformations to have an explicit knowledge about the same and to design bainitic steels...

In-situ investigation of strain-induced martensitic transformation kinetics in an austenitic stainless steel by inductive measurements

An inductive sensor developed by Philips ATC has been used to study in-situ the austenite (γ) to martensite (α′) phase transformation kinetics during tensile testing in an AISI 301 austenitic stainless steel. A correlation between the sensor output signal and the volume fraction of α′-martensite has been found by comparing the results to the...

Ferrite formation in Fe-C alloys during austenite decomposition under non-equilibrium interface conditions

Ferrous phase transformation kinetics: A combined dilatometric-calorimetric approach