Effect of tool rotational speed on force generation, microstructure and mechanical properties of friction stir welded Al-Mg-Cr-Mn (AA 5052-O) alloy

Friction stir welding (FSW) between 3 mm thick AA 5052-O aluminum alloy plates was investigated in the present study. Different welded specimens were produced by employing a constant tool traverse speed of 120 mm/min and by varying rotating speeds from 800 to 3000 rpm. The welded joints were characterized by its appearances, microstructural and mechanical properties at room temperature. The measurement of different forces acted on the tool during the FSW of AA 5052-O plates provided a significant insight to determine the quality of the welded joints. From the appearances of the welded joints it was evident that, except the tool rotational speed of 3000 rpm all other rotational speeds produced sound welded joints with smooth surface. The joint produced at 1000 rpm yielded a maximum tensile strength of 132 MPa which was 74% of the base material strength. Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) analyses on the stir zone suggested that, beta-Mg2Al3 intermetallic phases of the base material were mechanically fractured, smeared and mixed to different geometries due to tool stirring. The dissolution and redistribution of beta-Mg2Al3 second phase particles in the stir zone had a considerable effect on the reduction of the tensile strength of the welded joints. The reduction in hardness at the nugget zone (NZ) of the welded joints under different tool rotational speeds could be attributed to the dislocation of Mg-rich phases and segregation of Mg solute atoms at grain boundaries, which drew solute Mg atoms away from the alpha-aluminum matrix. (C) 2014 Elsevier Ltd. All rights reserved

Preliminary study on the feasibility of friction stir welding in 7075 aluminium alloy and polycarbonate sheet

Joining of dissimilar materials, especially in the case of polymer and metal, is significantly challenging because of the difference in chemical, mechanical and thermal properties of the materials. In this paper, a feasibility study of dissimilar materials joint between 7075 aluminium alloy and polycarbonate sheet was conducted by using friction stir welding through butt joint. A series of friction stir welding experiments were executed at various levels in order to obtain good joint. The preliminary results indicated that 7075 aluminium alloy and polycarbonate sheet were successfully joined with the aid of frictional heat energy originated from the friction stir welding process. The formation of 7075 aluminium alloy dislocation at the polycarbonate sheet side was clearly observed at the welding interface, which believed to be contributing to the weld strength. The effects of traverse and spindle speed on weld properties as well as the effect of appearance at joint interface are discussed in the paper

Utilising friction spot joining for dissimilar joint between aluminium alloy (A5052) and polyethylene terephthalate

The weld strength of thermoplastics with aluminium alloy, such as high density polyethylene and polypropylene sheets, is influenced by friction stir welding parameters. This paper focuses on the preliminary investigation of joining parameter at various levels as well as the mechanical properties of friction spot joining (FSJ) of aluminium alloy (A5052) to polyethylene terephthalate (PET). A number of FSJ experiments were carried out to obtain optimum mechanical properties by adjusting the plunge speed and plunge depth in the ranges of 5-40 mm min and 0.4-0.7 mm respectively, while spindle speed remains constant at 3000 rev min . The results indicated that A5052 and PET successfully joined with the aid of frictional heat energy originated from the friction spot welding process. The effect of plunge speed on the joined area and the effect of formation of bubbles at the interface of joints on the shear strength of joint are discussed

Dissimilar friction stir welding between polycarbonate and AA 7075 aluminum alloy

In this paper, the effects of process parameters, such as the tool rotational and traverse speeds, on temperature evolution and the microstructural and mechanical properties of dissimilar friction stir welding between 3 mm thick AA 7075 aluminum alloy and polycarbonate (PC) plates were investigated. The tool rotational and traverse speeds were varied from 3 000 to 3 500 rpm and 50 to 150 mm min(-1), respectively. The joint fabricated at 3 250 rpm and 100 mm min(-1) yielded a highest tensile load of 586 N. Microstructural analysis of the stir zone revealed an interlock phenomenon, the transportation of AA 7075 in polycarbonate, and the absence of ceramic-type (carbide, hydride or oxide) compounds. Microhardness (HV) measurement on the weld zone showed an uneven distribution due to the complicated microstructure of the welded joint. The maximum temperatures of 164 degrees C and 66 degrees C were obtained at 3 250 rpm and 100 mm min(-1) at a distance of 5 mm away from the welding centerline in the AA 7075 and PC side, respectively