Biochar-assisted copper-steel dissimilar friction stir welding: mechanical, fatigue, and microstructure properties

This present work investigates the effect of adding novel biochar microparticle into the welding zone of dissimilar friction stir welding of AISI-SAE 1010 (steel)–CDA 101 (copper) alloys. The primary aim of this work was to produce efficient weld joints in AISI-SAE 1010–CDA 101 alloys using biochar as solid lubricant via friction stir welding process. The biochar particles were prepared from rice husk biomass via carbonization process. The welding was performed using tapered pin profiled tool with rotational speed of 900 rpm, traverse speed of 30 mm/min, axial load of 5 KN, dwell time of 5s, plunging depth of 0.2mm, and biochar additions of 0.5, 1, 2, and 4wt%. The highest tensile strength of 205 MPa, elongation of 44%, yield strength of 177MPa, strain value of 36, and Vickers hardness of 121 were observed for FSW joints made using 2wt% of biochar content. Large addition of biochar up to 4wt% marginally affects the properties. Similarly, the fatigue strength of 157MPa was observed for weld made using 2wt% of biochar. The microstructure of biochar-assisted weld nugget shows highly refined less thermally affected grains. The grains were in equiaxial with distortion-free. The EDAX report confirms the presence of copper, iron, and carbon on the weld nugget, which indicates fine mixing of parent metals with solid lubricant. These mechanical properties improved environmental friendly dissimilar welding method could be used in industrial applications such as automobile, aerospace, construction, defense, medical, energy where high strength with high durable weld joints are required to meet the current technology demand, and process economy.