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Deformation-induced phase transformation in atype 304 austenitic stainless steel has been studied in tension at room temperature and -50°C. The evolution of transformation products was monitored using X-ray diffraction (XRD) line profile analysis of diffraction peaks from as ingle XRD scan employing the direct comparison method. Crystallographic texture transitions due to deformation strain havebeen evaluated using (111) g pole figures. The tensile stress-strain data have been analyzed to explain the influence of underlying deformation-induced microstructural changes and associated texturechangesinthe steel. It is found that the initial stage of rapidlydecreasing strain hardeningrate in type 304 steel is primarily influenced by hcp e -martensite formation, and the seconds tage of increasing strain hardening rate is associated with an increasei nt he a # -martensite formation. The formation of e -martensite is associated with ag radual strengthening of the copper-type texture componentsupto15pct strain and decreasing with further strain at -50°C. Texture changes during low-temperature deformation not only change the mechanism of e -martensite formation but also influence the strain rate sensitivity of the present steel.

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International audienceThe present paper reports the results of a blind round robin test dedicated to the measurement of the retained austenite content of different TRIP assisted multiphase steels. Various surface and volume techniques, i.e. light microscopy, X-ray diffraction, electron backscattered diffraction (EBSD), magnetic saturation, thermal diffusivity and laser ultrasonics, were used by different partners. The compiled results show a quite large variability of the estimated retained austenite content, particularly for well established techniques, such as X-ray diffraction (XRD) and magnetisation. On the other hand, emerging techniques like EBSD, thermal diffusivity and laser ultrasonics warrant further investigations

The effect of low-temperature aging, with aging temperatures up to 170 °C, on a cold-rolled CMnCrMo dual-phase (DP) ferrite-martensite steel was investigated. This material was processed using three different intercritical annealing treatments, leading to DP structures with different microstructures and properties. It has been found that both the aging in the ferrite phase and the tempering in the martensite play an important role in the mechanical behavior of the material with regard to the strain aging phenomena. The yield stress increase accompanying the aging phenomenon revealed three separate aging stages. In the present study, those stages were determined to be the result of the pinning of dislocations in the ferrite, the C-cluster formation, or low-temperature carbide precipitation in the ferrite and the volume contraction of the martensite due to formation of low-temperature carbides, leading to the relief of residual stresses in the ferrite. In the absence of a clear yield point, a new method is proposed to measure the increase in yield stress due to aging only.