A bainitic microstructure with fine ferrite plates (20 to 40 nm) in a matrix of high-carbon retained austenite, obtained by isothermal transformation at 200°C, was characterized with an energy-compensated optical position-sensitive three-dimensional atom probe. The average carbon concentration in the austenite was found to be 8.0±1.6 at.% and in the bainitic ferrite 1.1±0.7 at.%. The latter con...

Calculations verify that carbon diffusion may occur during the lath martensite fomtion. Accordingly,the diffusion of int2rstitial ator ions must be taka into account nhfn martmitic transformtion is defined as a diffusionless transformation. In derivation of the kinetics equation of the ath& martensitic transfomtion,rzgardng the c a r h diffusion, i .e.the enrichment of the austenite during the ...

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...

Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure-in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate ...

the quenching and partitioning (q&p;) process is a new heat treatment cycle to produce the third generation of advanced high strength steels based on diffusion of carbon from martensite to retained austenite phase. the application of this process for various steels leads to a remarkable combination of mechanical properties including high strength and good ductility. using this process in automo...

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...

Using metallurgical models, three steels were designed to obtain carbide-free bainitic structures in the as-rolled condition. Experimental castings were hot-rolled in a pilot mill and their austenite decomposition kinetics were measured using dilatometry. Tensile and Charpy impact properties were measured and the microstructures were characterised using X-ray diffractometry, optical and scannin...

Transformation induced plasticity (TRIP) assisted steels contain a small quantity of carbon enriched retained austenite, which transforms into martensite during the course of plastic deformation. Transformation of this kind can be induced by both stress and plastic strain. The detailed mechanism by which the martensite is induced is different for these two scenarios. An attempt is made here to ...

The possibility to obtain multiphase steels with considerable fractions of retained austenite, which is of key interest for the occurrence of the TRIP effect, is investigated in steels with low amounts of Si and Al. Special emphasis is dedicated to the microstructural observation of this phase, since its volume fraction, distribution and stability, related to the carbon content, will determine ...