Friction stir welding (FSW) is a solid-state weld process that broadly used by industries and preferred rather than other weld process due to its capability to weld similar and dissimilar materials under high quality. It can be used to weld high strength materials to weight ratio such as aluminum alloys, copper alloys, and magnesium alloys which are normally hard to be welded by conventional fusion welding processes. FSW has significant advantages over other weld processes, such as, automatic, used for most materials, can be carried out in all positions, low distortion, no shielding gas or filler are needed, can be employed under water, and environmentally friendly. On the other hand, FSW is like any other weld methods can produce series visualized or hidden defects if improper care used to process preparation. Of these defects are cracks, pores, voids and tunnel, fragment, lack of penetration, kissing bond, hooking, flash, and other surface defects. This paper presents the most common defects types that can be produced in FSW process and weaken the joint. The defects will be reviewed from some of significant studies made by researchers, and their results will be used to build up a guidance to detect and prevent these defects and their causes to assure producing a free defect weld joint.

/pdf/review-the-common-defects-in-friction-stir-welding-w9jchtfih5.pdf

Review The Common Defects In Friction Stir Welding

Dissimilar friction stir welding of Al to non-Al metallic materials: An overview

Friction stir processing (FSP) is an effective technique in microstructural refinement. It is expected to make a great change in the manufacturing industries. However, the weak region of thermo-mec...

Parametric optimization for friction stir processing in Al-Zn-Mg-Cu alloy

Friction stir welding (FSW) is an effective technique for producing quality welds and resolving solidification issues of aluminium alloys found in fusion welding (FW) techniques. This study seeks to establish the effect of welding speeds (WSs) of 25, 45, 65, and 85 mm/min with a constant tool rotation speed (TRS) of 1000 rpm and a tool tilt angle (TTA) of 20. Furthermore, mechanical testing was performed to determine the tensile strength, microhardness, and residual stresses. In addition, microstructure characterization was performed using optical microscopy, SEM/EDS and EBSD to identify the quality assurance of the dissimilar AA7050 T7651-AA2014A T6 weld joint. The results indicated that while the WS increased from 25 to 85 mm/min, the width of the stir zone decreased from 9.497 mm to 6.315 mm, according to the macrostructure analysis. Moreover, microstructural analysis reveals the direction of material flow and grain structure on the advancing side (AS) and retreating side (RS) of the thermo-mechanical affected zone (TMAZ) in the weldment. EBSD analysis reveals the 65 mm/min weld joint has a finer grain size (the average grain size is 2 µm) compared to other WS. Residual stress analysis also reveals compressive residual stress in all weld zones except for RS. The RS of residual stress values for 25–85 mm/min weld joints is 3, 7, 4, and 5 MPa. At the same time, UTS values were obtained as 274 MPa (25 mm/min), 317 MPa (45 mm/min), 332 MPa (65 mm/min), and 308 MPa (85 mm/min), and fracture occurred on the RS of all the welded joints, which was confirmed by harness values that are (AS and RS) 115–157 HV and 63–154 HV, respectively. The observed results show that WS at 65 mm/min has better mechanical and metallurgical properties than other welding speeds because of proper material mixing and finer grains obtained in the weldment, which resulted in higher UTS values being attained for WS at 65 mm/min of the FSW joint. 

Effect of welding speeds on the metallurgical and mechanical property characterization of friction stir welding between dissimilar aerospace grade 7050 T7651-2014A T6 aluminium alloys

The permanent metal joining processes play a vital role in assembling the complex aluminium structures of the aerospace, automotive, marine, and oil industries. The invention of friction stir welding (FSW) redefined the mechanism of metal joining to produce high-quality welds by eliminating the consumption of electrodes and shielding gases, resulting in economical processes. Research works still lack to explore the application of FSW in complex geometries. In this view, the present work reports a critical review of various geometries welded by FSW, mainly circular geometries that are majorly used in the oil and gas industries. The various aspects of the FSW of pipes, such as process facilitation, process parameters, tool material selection, and tool design selection are discussed. The paper also presents insights into the parameters responsible for the weld quality, the feasibility of optimization techniques, and the status of various fixture arrangements. The facilitation requisites for FSW of pipes are also provided based on the reviews made. The review concludes by discussing the challenges associated with the FSW of pipes, economic aspects, and future research directions.

/pdf/a-contemporary-review-on-friction-stir-welding-of-circular-hgxa1yvv.pdf

A Contemporary Review on Friction Stir Welding of Circular Pipe Joints and the Influence of Fixtures on This Process

Filling Friction Stir Welding (FFSW) is an FSW completing process, in which the exit-holes at the end of friction stir welded lines are filled by a rotational semi-consumable pin. In the present st...

A.H. Ghavimi

Papers

Exit-hole repairing in friction stir welding of AA5456 pipe using consumable pin