A Novel Flat Friction Stir Spot Welding of Triple Sheet Dissimilar Aluminium Alloys: Analyzing Mechanical Properties and
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ORIGINAL ARTICLE
A Novel Flat Friction Stir Spot Welding of Triple Sheet Dissimilar Aluminium Alloys: Analyzing Mechanical Properties and Residual Stresses at Weld Region Sachin Jambhale1
•
Sudhir Kumar2 • Sanjeev Kumar3
Received: 19 December 2019 / Accepted: 12 June 2020 The Indian Institute of Metals - IIM 2020
Abstract In present research work, a novel flat friction stir spot welding was performed on three dissimilar Aluminum alloy sheets (two sheets of AA6082-T6 and one sheet of AA6061-T6). The microstructural features and mechanical properties of joints were investigated at various parameters like tool tilt angle, tool rotational speed, dwell time and tool plunge depth. The optimized value of the response parameter was obtained using Taguchi orthogonal array L27. An increase in tool tilt angle, tool rotational speed and dwell time had improved the microhardness. Optical microscopy, scanning electron microscopy, microhardness tests, lap shear strength test and X-ray diffraction were employed to study the characterization of joints. The present investigations were carried out to correlate the microhardness with microstructural characterization of joints at different welding conditions. It was observed from the XRD analysis that the compressive residual stresses were developed due to reaction for forces exerted by the tool shoulder. Fractograph of joints exhibited mixed mode of fracture with the presence of dimples, transgranular texture and cleavage facets. The comparision of joint efficiency of FFSSW weldment with other variants was done. Keywords Heat-affected zone (HAZ) Thermo-mechanically affected zone (TMAZ) Analysis of variance (ANOVA) & Sachin Jambhale [email protected] 1
MGMCoET, Noida, UP, India
2
GNIOT, Greater Noida, UP, India
3
J.C. Bose University of Science and Technology, YMCA, Faridabad, India
Scanning electron microscopy (SEM) X-ray diffraction (XRD) Microhardness
1 Introduction The increase in use of aluminum alloys with lighter weight and higher strength in automotive sector need to pay more attention on research in joining processes of such alloys [1, 2]. A modern vehicle typically contains around 2000–5000 spot welds. Innovative lightweight materials for the components of vehicles have been developed for new generations of automobiles. Manufacturers are applying expertise to develop cost-effective joining solutions well beyond conventional spot-welding. Resistance spot welding (RSW) is considered as one of main joining technique that has been extensively used in the automotive industry. Some problems like consumption of tool during joining, large heat distortion, formation of thick and brittle phases at joint interface and poor weld strength in joints are associated with RSW. Interest in alternative joining technologies, such as friction stir welding (FSW), is increasing. FSW is also getting interest from manufacturers of airplanes, appliances, trucks, trains and even consumer electronics. Conventional RSW is replaced by friction stir spot welding (FSSW), which can
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