Publications Scientifiques

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Author: search.filters.author.Badji, Riad

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    Dissimilar FSW of AA2024 and AA7075 : effect of materials positioning and tool deviation value on microstructure, global and local mechanical behavior
    (Springer, 2021) Hadji, Idir; Badji, Riad; Gaceb, Mohamed; Cheniti, Billel
    In this work, the effect of material location and tool deviation on global and local mechanical behavior of dissimilar AA2024/ AA7075 friction stir weld joints was investigated. The results showed that increasing the tool deviation value up to 1 mm towards the soft material, fixed in the advancing side, improved the material mixing quality and enhanced the grain refine- ment in the stir zone. It was found that the highest ultimate tensile strength was obtained when the AA7075 alloy was fixed in the retreating side for 1-mm tool deviation towards the AA2024 alloy. Above this deviation value, a gradual decrease of the global mechanical properties of the weld joints was noticed. The digital image correlation (DIC) technique coupled to tensile testing revealed an improvement of local strain in the stir zone as well as the heat-affected zones of the dissimilar joints when the AA2024 alloy was positioned in the advancing side
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    Investigation of the effect of aluminum alloy position on residual stresses in dissimilar fsw weld by using the ultrasonic method
    (IOP Publishing, 2018) Hadji, Idir; Badji, Riad; Gaceb, M.; Kherrouba, N.; Rabahi, L.
    The main goal of this study is to show the effect of the advancing side (AD) and the retreating side (RT) position on the Residual stresses and local mechanical behaviour of dissimilar friction stir welds of aluminum alloys AA2024-T3 and AA7075-T6. Different samples were produced by varying the rotational speed of the tool (1200 and 1400 rpm) and the alloy position regarding the advancing side of the tool. Ultrasonic Method has been used to evaluate Residual Stresses. This method is based on the acoustoelastic effect, which measures the velocity variation of the elastic waves according to the stress state of the material. This can be achieved through a calibration test, which permits the determination of the acoustoelastic coefficient (K). The results show a tensile stress in the Nugget (N), the heat affected zone (HAZ) and a compression stress in the base metal (BM). Increasing the rotational speed reduces the amplitude of the longitudinal residual stresses with a high reduction in the case where AA7075 - T6 is in the advancing side whit 1400 rpm. This has been directly associated to the increase in the heat input and the reduction of the thermal mismatch between different areas of the weld. The microstructure effect of aluminum alloy position acts on the acoustoelastic constant K. The choice of t0 corrects the overestimated residual stresses in the (HAZ) and (N).
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    Microstructure, corrosion and magnetic behavior of an aged Dual-Phase stainless steel
    (Springer, 2018) Ziouche, Aicha; Haddad, A.; Badji, Riad; M. Zergoug, M. Zergoug; Zoubiri, N.; Bedjaoui, W.; Abaidia, Seddik-El-Hak