In this work, the influence of carbon nanotube (CNT) addition on the micro-structure and tensile properties of laser-welded AA5052 aluminium alloy joints was systematically investigated, with emphasis on quantifying the individual contributions of distinct strengthening mechanisms. The addition of CNTs refined the fusion zone grain size by approximately 31% and reduced crystallographic texture intensity by 42%. Consequently, the tensile strength and elongation of the CNT-reinforced joints reached 256.11 MPa and 15.81%, respectively. Quantitative analysis demonstrated that load transfer and dislocation strengthening were the predominant mechanisms, whereas grain refinement played a negligible role. This study provides novel quantitative insights into the synergistic strengthening mechanisms of CNTs in laser-welded aluminium alloys.
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