Performance evaluation of thermally reduced ex situ wheat husk biocarbon-assisted dissimilar AA7075 T651-magnesium AZ31B friction stir welded joints

The emerging industrial need requires effective energy efficient materials and processing technologies that can be made engineering better. In this present study, a new attempt has been made to improve the effortless joining process of AA7075 T651-AZ31B base materials by using non-consumable rotating tool with novel biolubricant (biocarbon). The biocarbon was thermally reduced (TRB) from wheat straw via low temperature pyrolysis process at 450 degrees C. The fine biocarbon particles of sizes of about 1-3 mu m are then surface modified to prevent the clustering effect using a silane chemical. The sound weld joints were prepared with the help of vertical machining centre as lap joint format. According to the result, the thermal reduction on the biocarbon particle makes the particle lesser impurities. The ordered structure biocarbon effectively offered the lubrication effect and improved the microstructure. The weld made with 1 vol% of biocarbon scored the highest tensile strength of 348 MPa, % of elongation of 28, microhardness of 106 Hv, and Charpy impact toughness of 23.4 J respectively. Similarly, the wear properties show improved wear resistance for large biocarbon particle dispersed weld. The microstructure of welded portion shows highly refined and typically smaller grains. The heat-affected zone (HAZ) and thermo-mechanically treated zone (TMTZ) are typically occupied lesser orbit from the weld pool. The weld bead microstructure reveals improved joining geometry for biocarbon-assisted welds even after more trials. These high strength and joint efficient dissimilar welded joints could be used in automotives, airlines, and shipping where joining of high strength alloys frequently done.