Characterizations of weld defects, intermetallic compounds and mechanical properties of friction stir lap welded dissimilar alloys

• Published in: Materials characterization 2020-02, Vol.160, p.110115, Article 110115
• Main Authors: Mahto, Raju Prasad, Kumar, Ravi, Pal, Surjya Kanta
• Format: Article
• Language: English
• Subjects: Dissimilar alloys; Intermetallic compound; Kissing bond; Weld defects; X-ray micro-computed tomography
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2019.110115

This experimental investigation describes the effect of tilt angle and rotational speed on the characteristics of welding defects, intermetallic compounds, weld strength and micro-hardness in friction stir welding of thin sheets of AA6061-T6 and AISI304. Qualitative and quantitative assessments of the welding defects have been made by using X-ray micro computed tomography and metallographic study. Three-dimensional tomography and special distribution of internal voids (pores) have been discussed by correlating it to different values of tool rotational speed and tilt angle. Internal defects were localized in the stir zone. Welding at a tilt angle of 1° reduced both surface and internal defects. Non-uniform thickness of intermetallic compound (FexAly) layer has been found in the weld zone whose thickness varied with the values of process parameters. Higher weld porosity, bigger steel hook defect and increased layer thickness of intermetallic compound caused a significant reduction in the joint strength and elongation. •Hook defects significantly deteriorates the load bearing capacity of the friction stir lap welded samples.•Non-uniform size and shapes of weld pores obtain in FSW of Al alloy and steel.•Kissing bond and lazy S defects have an insignificant effect on the failure locations.•Non-uniform of thickness of IMC layer forms at the weld interface.