Friction Stir Welding Case Study

Microhardness and microstructural analysis of friction stir welded AA5052-H34 joints
B. Magamai Radja,* and T. Senthilvelana aDepartment of Mechanical Engineering, Pondicherry Engineering College, Pondicherry University, Puducherry 605 014, India

Abstract
Friction stir welding a novel solid state welding which gains momentum in versatile applications viz., aerospace, marine, defense equipments and automobile industries. In the present work, AA 5052-H34 weldments have been prepared by FSW process. Optimization has been done by applying Taguchi’s L9 orthogonal array with three input parameters and each with three levels in order to obtain maximum hardness and desirable macro and microstructures. A maximum hardness of 95.2 HV which is 14% higher
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However, to expand the usage of aluminum alloys, more effective welding and joining techniques are required. Friction Stir Welding (FSW) has greater potential for aluminum alloys since it can significantly reduce weld defects such as porosity, cracks and distortions commonly encountered in fusion welded joints [8]. Al alloy with magnesium as the major alloying elements constitute a group of non heat treatable alloys (AA5XXX series) used for structural materials in automotive, aircraft and marine applications. Welding of this alloy using conventional technique leads to vaporization of Magnesium, which causes compositional changes in the weld seam [9]. Hence, to regain the Mg content (from AA5XXX series materials) FSW may be the feasible technique to overcome this …show more content…
Figure 4(a) and (f) Shows the microstructure of the parent metal AA5052-H34 with elongated parallel grains along the rolling direction at advancing and retreating sides respectively. Figure 4(b) shows the shoulder region with fragmented particles of eutectic constituents. The grains have fragmented due to stirring action of the tool. Figure 4(c) shows the interface zone of the advancing side alloy and the nugget zone. The nugget zone shows the re-crystallized grains of the alloy due to heat and fragmented due to mechanical stirring stress. The left side of the image shows the parent metal at the advancing side and the right side of the image shows the nugget zone. Figure 4(d) shows the microstructure of the nugget zone at close to the retreating side with fine fragmented particles where plastic flow is observed with uniform grain orientation. Figure 4(e) shows the interface zone of the NZ and TMAZ at the retreating side of the parent metal. The parent metal at the right hand side shows the coarsened larger size particles and the nugget zone shows fine fragmented

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