Please cite this article as: V. Javaheri, S. Kolli, B. Grande, et al., Insight into the induction hardening behavior of a new 0.40% C microalloyed steel: Effects of initial microstructure and thermal cycles, Materials Characterization,

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Deterioration of the toughness in heat-affected zones (HAZs) due to the thermal cycles caused by welding is a known problem in offshore steels. Acicular ferrite (AF) in the HAZ is generally considered beneficial regarding the toughness. Three experimental steels were studied in order to find optimal conditions for the AF formation in the coarse-grained heat-affected zone (CGHAZ). One of the steels was Al-deoxidized, while the other two were Ti-deoxidized. The main focus was to distinguish whether the deoxidation practice affected the AF formation in the simulated CGHAZ. First, two different peak temperatures and prolonged annealing were used to study the prior austenite grain coarsening. Then, the effect of welding heat input was studied by applying three cooling times from 800 °C to 500 °C in a Gleeble thermomechanical simulator. The materials were characterized using electron microscopy, energy-dispersive X-ray spectrometry, and electron backscatter diffraction. The Mn depletion along the matrix-particle interface was modelled and measured. It was found that AF formed in the simulated CGHAZ of one of the Ti-deoxidized steels and its fraction increased with increasing cooling time. In this steel, the inclusions consisted mainly of small (1–4 μm) TiOx-MnS, and the tendency for prior austenite grain coarsening was the highest.

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Single phase aluminium laminates of AA6063, AA2014 and AA6063/AA2014 composites were produced by accumulative roll bonding processed up to 6 cycles. The microstructure and texture of the initial materials and the sheets after 6 cycles were studied using electron backscatter diffraction and X-ray diffraction, respectively. It is observed that 6 cycles lead to an ultrafine grained microstructure. In both the single phase laminates and the composite the texture consists of the typical components for rolling and shear deformation of face-centred cubic metals. For all texture components, the intensity in the composite is about the average of the intensities in the single phase laminates. Therefore, the deformation process in the individual layers of the composite is comparable with that in the single phase alloys. K e y w o r d s : aluminium alloys, accumulative roll bonding, texture, microstructure