Stochastic Tensile Failure Analysis on Dissimilar AA6061-T6 with AA7075-T6 Friction Stir Welded Joints and Predictive Mo
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TECHNICAL ARTICLE—PEER-REVIEWED
Stochastic Tensile Failure Analysis on Dissimilar AA6061-T6 with AA7075-T6 Friction Stir Welded Joints and Predictive Modeling Thella Babu Rao
Submitted: 17 June 2020 Ó ASM International 2020
Abstract The issue of weld solidification cracking in fusion welding of highly alloyed aerospace aluminum alloys is eliminated in friction stir welding (FSW) because the base materials do not melt during welding. However, in FSW, the weld joint quality characteristics are found with highly sensitive for the variation of process variables. Therefore, this investigation deals with the analysis of the significance of FSW processing conditions, construction of stochastic tensile failure probability models for dissimilar AA6061-T6 with AA7075-T6 aluminum alloy friction stir welded joints, and postulation of their statistical predictive models. The experimental results have shown an effective mixing at the interface of both base alloys attributed to efficient bonding and resulted in the mechanical properties with the weld joints. A lowest tensile strength was achieved for the weld joint produced by the straight cylindrical profiled tool pin, which is 24.51% lower than the UTS of AA6061-T6 unwelded alloy while 59.09% lower than the AA7075-T6 unwelded alloy. The survival probability of the weld joints fabricated at 30 mm/min is 92% for 260 MPa applied stress, but the weld joints fabricated at 20 and 40 mm/min are 70 and 40%, respectively. For 50% reliability of the weld joint, the maximum allowable stress values suggested are 270, 288, and 255 MPa for processed at of 20, 30, and 40 mm/min welding speeds, respectively. The application stresses beyond 290 MPa, and the survival probability of the weld joints fabricated at 40 mm/min is zero. Empirical models postulated for tensile strength, ductility, and microhardness were fund with a reasonable
T. Babu Rao (&) Department of Mechanical Engineering, National Institute of Technology Andhra Pradesh, Tadepalligudem, West Godavari Dist., Andhra Pradesh 534 101, India e-mail: [email protected]
agreement with their experimental measurements statistically. The derived reliability and empirical models can be used to estimate the reliability of the welded joints and predict their mechanical properties to estimate and enhance the functional performance of the welded structures in automobile and aerospace applications. Keywords AA6061-T6 and AA7075-T6 aluminum alloys Friction stir welding Stochastic tensile failure probability models Mechanical properties Weibull statistical analysis Empirical modeling Experimental validation
Introduction The constantly increasing demand for the utilization of light-weight materials for aerospace and automobile components has been attracted the aluminum and its alloys as the potential for their use. These materials offer superior characteristics such as easy machinability, reasonable strength, high resistance to corrosion, and reasonably low cost [1]. In fusion welding of aluminum alloys, the solidificati
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