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© 2023, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.The surface of the commercial CoCr28Mo alloy was textured using a 20W pulsed fiber laser according to different beam scan strategies. Surface roughness and drop contact angle measurements made on the textured surface were used to evaluate the effects of process parameters. The surface topography was highly affected by both scan direction and beam overlaps named pulse-to-pulse overlap and scan overlap. As the beam overlap ratio increased, the amount of heat transferred to the unit area also increased, which caused more metal to evaporate in the interaction zone and form a more considerable amount of molten and re-solidified metal layer, resulting in a chaotic texture formation on the surface. The mean surface roughness values of textured surfaces for eighteen test samples ranged from 1 to 7 μm. These surface roughness values were in the micro-scale roughness value range. According to the results of the drop contact angles, the surface topography significantly changed the wettability. The test results were also analyzed by the Taguchi method considering signal-to-noise ratios and evaluated by analysis of variance. Considering the highest S/N values for each parameter, the optimum parameters combination for the laser engraving process was 45°/-45° for scan direction, 70 % for power, 1000 mm/s for scan speed, 50 kHz for frequency, 0.01 mm for hatch distance, and 75 ns for pulse duration.

This study focused on process factors, namely welding speed and tool rotation speed, to investigate the friction stir welded joint characteristics of AA 7075-T651 aluminum alloy via microstructural and mechanical properties. On the weld created using the parameters of 40 min/min welding speed and 630 rpm tool rotation speed, the coarsest grain size measured was 3.75 mu m; however, the finest grain with a size of 2.37 mu m was measured on the welded joint produced with 80 mm/min welding speed and 800 rpm tool rotation speed. The tensile strength with the highest value was achieved when welding parameters were set at 800 rpm tool rotation speed and 80 mm/min welding speed. The defective joints exhibited lower tensile strength and ductility. Hardness measurement results revealed that each welded joint had a "W" hardness profile.

The effect of tool rotation speed and welding speed on the microstructural and mechanical properties of AA 7075-T651 welded plates produced using friction stir welding is the research subject of this study. A basin-shaped stir zone characterized all friction stir welded joints' microstructures. The fracture location following the tensile test was found to be outside the stir zone for each welded joint. All welded joints were subjected to a 90 degrees root bending test. The tests were terminated before each welded joint could reach the 90 degrees bend angle in the stir zone. The stir zone of each welded joint was characterized by the fine and equiaxed grains with the effect of dynamic recrystallization. In addition, intermetallic particles were also detected to occur in the weld joint. Among the nine welded joints, the welded joint with the highest ultimate tensile strength of 382 MPa was produced with a tool rotation speed of 400 min(-1) and a welding speed of 80 mm min(-1). The highest welding efficiency of 71 % was obtained with the welding process parameters of 400 min(-1) tool rotational speed and 80 mm min(-1) welding speed. Increasing tool rotation speed caused the grain size to be coarser.

AA 3003-H24 aluminum alloy plates were butt-welded in order to investigate the effect of friction stir welding process variables on the structural properties of the welded joints. The welded joints were characterized using macro-structural investigations; and tunnel-type defects with varied sizes were detected to occur. At a welding speed of 50 mm/min, tunnel-type defects with large size were found to occur in joints welded with the tool rotational speed of 500 and 1000 rpm. The tunnel-type defects were detected to occur in welded joints produced with the process parameters of 80 mm/min welding speed and 500 and 800 rpm tool rotational speed. However, cavity-type defects were observed to occur at both welding speeds. Even, defects were found to occur in the welded joints, all welded joints were detected to fracture between the base metal and the heat-affected zone, except for the joints welded under the process parameters of 50 mm/min welding speed, 500 and 1000 rpm tool rotational speed. The highest ultimate tensile strength among all the welded joints was measured to be 128 MPa produced under the process parameters of 50 mm/min welding speed and 800 rpm tool rotational speed. It has been revealed that there is a good correlation between the size of the defects and the tensile properties of welded joints. An examination on the fracture surface of the welded joints revealed that welded joints were fractured in ductile manner except the joint produced under the process parameters of 50 mm/min welding speed and 500 rpm tool rotational speed.

In this study, AA 2024-T351 aluminum alloy plates were butt-welded using friction stir welding process at a constant welding speed of 63 mm/min and tool rotational speed of 400 and 630 rpm. Two welding seams were overlapped via shifting the pin towards advancing side or retreating side. The effect of friction stir welding parameters on mechanical and microstructural properties were investigated. Microstructural investigations and micro-hardness measurements were performed on the transverse cross section of welded joints. The decrease in tensile strength is attributed to the increase in tool rotational speed, leading to an increase in frictional heat generation regardless of overlapping of weld seams. Consistent correlation between tool pin type and other process parameters was found to occur, revealing that the higher tensile strength values were obtained in case pentagonal shaped pin was used. It was revealed that tapered threaded pin profile was resulted in producing defective welded joints; defects, located in the stir zone, were found to be effective on deteriorating the mechanical properties of welded joints.

The aim of this work is to present a case study relating to the dissimilar friction stir welding (FSW) ability of AA 7075-T651 and AA 6013-T6 by applying pin offset technique. An orthogonal array L18 was conducted to perform the overlapped weld seams using three different values of pin offset, welding speed and tool rotational speed along with two different pin profiles determine the impact of welding parameters on the tensile properties of friction stir welded joints. The nugget zone for each of overlapped weld seams exhibited a complex structure and also, the pin offset and profile also were found to have a great impact on the microstructural evolution of the nugget zone. The ultimate tensile strength, elongation at the rapture and bending strength of welded joints were measured in the ranges of 194-215 MPa, 1.79-3.34 % and 203-352 MPa. From the Taguchi based Grey relational analysis, the optimum welding condition was determined for the welded joint performed using a single fluted pin profile with the zero pin offset, tool rotational speed of 630 min(-1) and welding speed of 63 mm/min. Microstructural and macro-structural observations revealed that welded joints exhibiting lower tensile strength are consistent of various types of defects (e. g. cracks, tunnels and cavities). The fracture location of welded joints was found to be on the heat affected zone and between the heat affected zone and AA 6013-base metal. The tool and pin wear was not observed during the welding applications

The objective of the present study is to analyze the effect of dissimilar friction stir welding process parameters associated with the tool pin profile. Nine different welding experiments were conducted on EN AW 2024 and EN AW 5083 plates. Each of the welded joints was exposed to metallurgical and mechanical tests to determine the effect of the parameters on the welded joint's strength and characteristics. The welding responses or characteristics were analyzed using the statistical tools, grey relational analysis and analysis of variance. Thus, the contribution of each parameter to the process response (ultimate tensile strength and percentage of elongation) was analyzed, and an optimal welding condition was determined. The results of metallurgical analyses showed that the defective joints were mostly in the welded joints fabricated with a conical threaded pin, and the shape of the stir zone was affected by the pin profile and tool rotational speed. The metallurgical results were consistent with the tensile test results. Statistical analyses showed that the most effective parameter on the welded joint strength and elongation is tool rotational speed with 70.3%. While the tool pin profile affects the stir zone shape, the strength and elongation are not affected. The effect of welding speed (5.6%) is not significant on strength and elongation.

In this study, the friction stir weldingability of AA7075 / AA6013 aluminum alloy couple was investigated. Theinteraction between the pin profiles and overlapped welding seams affecting themechanical properties was investigated. The welded joints were characterized bytensile and bending tests. The highesttensile strength of 203 MPa and the lowest elongation at rupture with a valueof 2.12% were obtained in the absence of offset using a tool with conical pingeometry. Root bending strength and surface bending strength values were foundto be 288 MPa and 284 MPa, respectively. The highest root bending strength was measuredto be 293 MPa; it was obtained from the welded joint manufactured viaoffsetting the tool with the pentagonal pin profile on the AS direction. Thiswelded joint was found to contain defects. All welded joints joined by toolswith pentagonal pin profiles have been found to exhibit crack-typeimperfections affecting the tensile test results., Bu çalışmada, AA7075/AA6013 alüminyum alaşımçiftinin sürtünme karıştırma kaynak yöntemiyle kaynaklanabilme kabiliyetiincelenmiştir. Üst üste bindirilmiş kaynak dikişlerinin ve pim profillerininetkileşiminin mekanik özellikler üzerindeki etkisi araştırılmıştır. Çekme veeğme testleri ile kaynaklı bağlantılar karakterize edilmiştir. En yüksek çekmedayanımı olan 203 MPa ve en düşük kopma uzaması değeri %2,12 konik pimgeometrisine sahip takımın kullanılması ve herhangi bir ofsetin söz konusuolmadığı durumda elde edilmiştir. Kök eğme mukavemeti ile yüzey eğme mukavemetideğerleri ise sırasıyla 288 MPa ve 284 MPa olarak bulunmuştur. Eğme testisonrasında ölçülen en yüksek kök eğme mukavemeti değeri 293 MPa’dır ve beşgenpim profiline sahip takımın AS yönünde ofsetlenmesiyle imal edilen kaynaklıbağlantıdan elde edilmiştir. Bu kaynaklı bağlantı aynı zamanda kusurlar daiçermektedir. Beşgen pim profiline sahip takımlarla yapılan kaynaklıbağlantıların hepsinde çatlak tipi kusurlar tespit edilmiştir ki bu durum çekmetesti sonuçlarına da yansımıştır.

In the present study, the effect of two different pins which shaped in the triangular and straight helical threaded were associated with the ratio of the tool rotational speed to the welding speed on the mechanical properties of dissimilar friction stir welding (FSW) of EN AW 6082 and EN AW 5754. The responses of FSW process were investigated by the UTS, Ɛ% and hardness of weld joint. The results showed that the ratio of the tool rotational speed to the welding speed have a dominant effect on the weld joint strength., Bu çalışmada EN AW 6082 ve EN AW 5754 malzemelerin birbiri ile FSW kaynağında helisel diş açılmışve üçgen şekilli iki farklı pim ile takım dönme hızının kaynak hızına oranının mekanik özellikler üzerine etkisiincelenmiştir. FSW işleminin sonuçları kaynaklı bağlantının maksimum çekme mukavemeti, % şekil değiştirmeve sertliği ele alınarak incelenmiştir. Sonuçlar takım dönme hızının kaynak hızına oranının kaynaklı bağlantınınmukavemeti üzerine çok önemli bir etkiye sahip olduğunu göstermiştir.