Abstract:The aim of this paper is to determine the feasibility of submerged friction stir welding of 6061-T6 aluminium alloy on different water heads through macrostructuralanalysis.In this work, aluminium 6061-T6 alloy was friction stir welded under normal and submerged conditions at different rotational speeds of 400 rpm, 800 rpm, 1200 rpm, 1600 rpm. The water head was varied from 10 to 30 mm in the case of thesubmerged friction stir welding process. In both normal and submerged friction stir welding processes, a wel… Show more
“…The increase in the tensile strength and percentage elongation correlates with the microstructural grain sizes. Similar studies where the application of submerged multiple pass SFSP increased UTS were reported in the literature [23,[35][36][37].…”
Section: Tensile Propertiessupporting
confidence: 82%
“…The fourth SFSPed pass resulted in a very fine homogeneous grain structure. Similar work including the application of multiple pass SFSP was reported in the literature [34][35][36].…”
The AA6082–AA8011 friction stir-welded joints were subjected to submerged multiple pass friction stir processing to evaluate the microstructure and mechanical properties of the joints. A maximum of four submerged friction stir processed passes were used in this study. All the specimens were extracted from three different joint positions (start, middle and end). The tests conducted included microstructural analysis, tensile tests, hardness and fracture surface morphology of the post-tensile specimens, were performed using a scanning electron microscope (SEM). There was no particular trend in the microstructure and mechanical properties when looking at the specimen positioning in all the passes. The minimum mean grain sizes were refined from 3.54 to 1.49 µm and the standard deviation from 5.43 to 1.87 µm. The ultimate tensile strength was improved from 84.96 to 94.77 MPa. The four-pass SFSPed specimens were found to have more ductile properties compared to the one-pass SFSPed one. The hardness of the stir zones in all the passes was found to be higher compared to the AA8011 base material but lower than the AA6082 one. The maximum stir zone hardness of 75 HV was observed on the one-pass SFSP joints.
“…The increase in the tensile strength and percentage elongation correlates with the microstructural grain sizes. Similar studies where the application of submerged multiple pass SFSP increased UTS were reported in the literature [23,[35][36][37].…”
Section: Tensile Propertiessupporting
confidence: 82%
“…The fourth SFSPed pass resulted in a very fine homogeneous grain structure. Similar work including the application of multiple pass SFSP was reported in the literature [34][35][36].…”
The AA6082–AA8011 friction stir-welded joints were subjected to submerged multiple pass friction stir processing to evaluate the microstructure and mechanical properties of the joints. A maximum of four submerged friction stir processed passes were used in this study. All the specimens were extracted from three different joint positions (start, middle and end). The tests conducted included microstructural analysis, tensile tests, hardness and fracture surface morphology of the post-tensile specimens, were performed using a scanning electron microscope (SEM). There was no particular trend in the microstructure and mechanical properties when looking at the specimen positioning in all the passes. The minimum mean grain sizes were refined from 3.54 to 1.49 µm and the standard deviation from 5.43 to 1.87 µm. The ultimate tensile strength was improved from 84.96 to 94.77 MPa. The four-pass SFSPed specimens were found to have more ductile properties compared to the one-pass SFSPed one. The hardness of the stir zones in all the passes was found to be higher compared to the AA8011 base material but lower than the AA6082 one. The maximum stir zone hardness of 75 HV was observed on the one-pass SFSP joints.
“…In the role of higher rotation speed and traverse speed, the weld center temperature may reach the solid solution temperature of aluminum alloy, so that the Mg 2 Si reinforcing term particles dissolved in the α-Al matrix and the nucleation effect on the grain boundaries is weakened, resulting in abnormal grain growth in the welding process. According to the research of Rathinasuriyan et al [26], excessive welding heat input in friction stir welding leads to turbulent flow in the weld fusion zone, thus promoting the formation of defects. Figure 11 shows different rotation speeds and traverse speeds under the influence of grain boundary content.…”
The two main process parameters of Bobbin tool friction stir welding (BT-FSW) are ω (rotational speed) and v (traverse speed). Both of these factors have a significant effect on heat input, microstructure, and mechanical properties. At present, most studies on friction stir welding adopt the control variable method to study the thermal cycling during the welding process and the mechanical properties of joints, and there are few studies on changing the two process parameters at the same time, because it can be difficult to assess the correlation between heat input and mechanical properties when changing both factors at the same time. In this study, the w/v ratio is defined as the thermal index, which is a characteristic value of heat input. The study uses ABAQUS 6.5 software to establish a BT-FSW CEL (coupled Eulerian–Lagrangian) thermal coupling model. This model explores the relationship between joint thermal cycles, microstructure, and mechanical properties for different w and v values with the same w/v ratio. The results show that increasing rotational and traverse speeds under the same w/v ratio leads to an increase in the peak temperature of the nugget zone (NZ). However, the peak temperature of the thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ) remained almost constant. Joint strength was highest at a rotational speed of 750 r/min and a traverse speed of 650 mm/min, with a yield strength of 227 MPa. As rotational and traverse speeds increased, the recrystallized grain content of the NZ showed an increasing trend followed by a decreasing trend. The recrystallized grain content of the advancing side thermo-mechanically affected zone (AS-TMAZ) and retreating side thermo-mechanically affected zone (RS-TMAZ) showed a decreasing trend. Joint hardness had a “W” shaped distribution, with the highest average hardness value found in the NZ.
“…Gambar 7 menunjukan perbandingan besar daerah lasan berdasarkan perbedaan besar diameter pin pada tool, dimana semakin besar diameter pin maka akan semakin besar pula daerah lasan. Penelitian ini juga menujukkan struktur makro akibat pengadukan logam yang berbentuk onion ring seperti pada penelitian R. Chandran [20]. Semakin besar diameter pin pada tool maka daerah lasan akan semakin besar.…”
Section: Analisis Cacat Dan Struktur Makrounclassified
Aluminium merupakan logam yang memiliki sifat mampu las yang kurang baik dibandingkan dengan jenis logam lainnya. Hal tersebut dikarenakan memiliki konduktifitas panas tinggi, koefisien muai besar, dan reaktif dengan udara sehingga mudah terbentuk lapisan oksida (Al2O3) sehingga menghasilkan temperatur cair lebih tinggi dari aluminium murni. Panas yang berlebih pada metode penyambungan GTAW dan GMAW rentan terjadi cacat seperti porositas, crack dan distorsi. Proses Friction Stir Welding (FSW) bisa menjadi solusi untuk mengatasi masalah cacat yang muncul karena proses penyambungan terjadi dibawah temperatur cair logam aluminium. Penelitian ini bertujuan untuk mendapatkan parameter pengelasan yang optimum dengan mengetahui sifat mekanik dan struktur mikro hasil proses FSW pada pelat aluminium 6061-T6. Proses FSW aluminium tipe butt joint tebal 6 mm menggunakan putaran tool konstan 1500 rpm, kecepatan pengelasan 29 mm/min dengan variasi ukuran berdiameter pin 6 mm , 8 mm dan 10 mm. Hasil sambungan spesimen dengan pin berdiameter 6 mm memiliki sifat mekanik terbaik dengan kuat tarik 144 MPa dan kekerasan 70,27 HVN dibanding spesimen lainnya. Sedangkan pada spesimen dengan pin berdiameter 10 mengalami cacat berupa void (rongga) kecil yang terdapat pada bagian permukaan. Parameter optimum untuk proses FSW aluminium 6061-T6 menggunakan pin dengan diameter 6mm menghasilkan sifat mekanik dan struktir mikro lebih baik daripada penggunaan diameter pin 8 mm dan 10 mm
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