The Effects of Pin Offset for FSW of Dissimilar Materials: A Study for AA 7075 – AA 6013

The trend in welding of dissimilar aluminum alloys oriented to new application techniques to increase the functionality and perform the welding procedure without any problem in the welded joints. The pin profile and process parameters determined for the friction stir welding greatly affect the weldability and strength of the welded joints. In addition, it is also considered that the pin offset is also an effective factor on the strength and microstructure of welded joints. In the present study, aluminum alloys AA 6013–T6 and AA 7075–T651 were welded with the FSW process applying pin offset technique. The changes in the mechanical and microstructural properties were investigated. The onion ring structure was observed in all of microstructure of weld stir zone. Except the welded joint fabricated with the tool rotational speed of 400 rpm for both without pin offset and with offset to retreating side, all the welded joints were fractured at the base metal region and heat affected zone in AA 6013 alloy. The welded joints fabricated with the tool rotational speed of 400 rpm consisted of small and large cavity-type defects. Although defects were found to occur in the welded joints, none of the welded joints were fractured at the SZ during the tensile and bending tests. The ultimate tensile strength and elongation at rupture of the dissimilar FS welded joints were ranged between 164 MPa and 179 MPa, 6.5 and 7.6%, respectively. These defects were found to affect the ductility feature of the welded joints. The pin offset direction was found to affect the volume of parent materials in the stir zone. Hence, the material volume in the onion rings changes and, the hardness distribution is also affected by the changes in the material volume.   Keywords: aluminum alloys, friction stir welding parameters, fracture analysi

The Effect of Helical Pin Profiles on the Friction Stir Welding Performance of Aluminium Alloy AA6082

WOS: 000320151700001In this study, one of the solid state welding methods, friction stir welding, was studied with the AA6082 aluminum alloy. Two types of pins with a special geometry were used to investigate the effect of pins profile, tool rotational speed, and welding speed on the mechanical properties of welded joints. The pin profile was associated with weld joint properties such as tensile strength, elongation, bending strength, bending force, hardness distributions and temperature. Results have shown that the friction surface area of the pin has a significant role on the mechanical behaviour of the joint. The results of tensile tests associated with the pin profile indicate that the helical two-flute pin has a high tensile strength and elongation compared to the helical four-flute pin. Discrepancies in the tensile strength of the welded samples of the two pin profiles have been found between 37-55 % at the same welding conditions. Despite the relatively poor static properties, the helical four-flute pin has better bending properties. Higher bending strength and force (260.634 MPa and 347.513 daN) were obtained at test conditions of 2000 rpm and 100 mm/min. Bending without any defect on the joint was achieved at 2000 rpm and 200 mm/min. The effect of welding parameters on the hardness profile was not clear, and it has been observed that, in comparison, the helical two-flute pin did not create a remarkable difference with regard to hardness.Dokuz Eylul University in TurkeyDokuz Eylul University [2011.KB.FEN.045]This study was financially supported by Dokuz Eylul University (Project No: 2011.KB.FEN.045) in Turkey. The author would like to thank for the financial support

Analyzing dissimilar friction stir welding of AA5754/AA7075

WOS: 000330220300013AA5754/AA7075 was butt-welded by friction stir welding, and the joint of each weld case was identified by ultimate tensile strength, percentage of elongation, and hardness. Moreover, the significance of each parameter was investigated, and a mathematical relation was constructed by regression analysis. A defect-free joint was achieved in the case of a weld produced with 1000 rpm of tool rotational speed, 80 mm/min of welding speed, and an 22-mm tool shoulder diameter. Most of the failures are located at the bottom of the pin and side of AA7075. The ultimate tensile strength (UTS) decreases with increasing welding speed (WS) or increasing tool rotational speed (TRS). Hardness distribution in the weld zones varied dependent on the nugget zone formation affected by TRS and WS. The present study also investigated the significance and contribution of each parameter on the UTS by analysis of variance (ANOVA). From the results of ANOVA, the conclusion reached is that the all the parameters have a great influence on UTS. The contributions are 41.41 % for WS, 17.58 % for diameter, and 13.28 % for TRS. Moreover, a full quadratic model was constructed between the parameters and the UTS value. The results show that the variation from the predicted values was between 0.41 % and 10.36 %. The strength of the model was analyzed by R-Sq. The achieved R-Sq is 0.892, which means that there is a strong relation between predicted and actual values.Dokuz Eylul UniversityDokuz Eylul University [2011.KB.FEN.045]This study is fully supported by Dokuz Eylul University under project no. 2011.KB.FEN.045. The author would like to acknowledge this financial support

Investigation of micro-milling process parameters for surface roughness and milling depth

WOS: 000290164500013The main objective of this study is to investigate the micro-milling performance of the AISI H13 with different process parameters namely laser power, scan speed, frequency, and fill spacing using 30W fiber laser marking machine and to find the optimal operation conditions for minimum surface roughness and maximum milling depth. The 108 different combinations occurred with the interaction of each level of the parameters used in this study. Therefore, the main contribution of this paper to the related literature is that it produces new evidence regarding the effects of the multi-scan times on both surface roughness and milling depth. The experimental results are showed that 0.03 mm of fill spacing, the highest scan speed (800 mm/s), lowest frequency (20 kHz), and laser power (60%) produced better surface roughness, which is 1.75 mu m. The deeper cavity on the geometry is obtained under the experimental combination as 200 mm/s of scan speed, 0.02 mm of fill spacing, 60% of laser power, and 40 kHz of frequency, which is 195 mu m. The regression analysis was used to develop a mathematical model and determine the effect of process parameters on the surface roughness and milling depth. The results of subsequent tests verifies regression models.Ege UniversityEge University [35MUH08]We are grateful to Laser Mikron Ltd. Sti. Company where the laser milling experiments were performed in Izmir, Turkey. This work was supported by Ege University under project no.35MUH08

A Case Study for the Welding of Dissimilar EN AW 6082 and EN AW 5083 Aluminum Alloys by Friction Stir Welding

The aim of this study is to investigate the effect of keeping constant the tool rotational speed to the welding speed ratio (υ ratio) on the mechanical properties of the dissimilar friction stir welding of EN AW6082-T6 and EN AW5083-H111. Two different pins shaped as triangular and pentagonal were associated with the constant υ ratio. From the tensile test results, it was found that the υ ratio does not create an evident change in the weld joint strength. The small cavity- and tunnel-type defects were observed at the nugget zone and located on the advancing side of the pin. These defects caused a decrease in the strength and elongation of the weld joint. The most important inference obtained from the experimental results is that if the υ ratio is kept constant, the weld joint strength for each weld does not correspond to a constant value

A Case Study for the Welding of Dissimilar EN AW 6082 and EN AW 5083 Aluminum Alloys by Friction Stir Welding

The aim of this study is to investigate the effect of keeping constant the tool rotational speed to the welding speed ratio (υ ratio) on the mechanical properties of the dissimilar friction stir welding of EN AW6082-T6 and EN AW5083-H111. Two different pins shaped as triangular and pentagonal were associated with the constant υ ratio. From the tensile test results, it was found that the υ ratio does not create an evident change in the weld joint strength. The small cavity- and tunnel-type defects were observed at the nugget zone and located on the advancing side of the pin. These defects caused a decrease in the strength and elongation of the weld joint. The most important inference obtained from the experimental results is that if the υ ratio is kept constant, the weld joint strength for each weld does not correspond to a constant value

An Investigation of WEDM Process Parameters on the Surface Roughness of Al/B4Cp Metal Matrix Composites

2nd International Congress on Advances in Applied Physics and Materials Science (APMAS) -- APR 26-29, 2012 -- Antalya, TURKEYWOS: 000309528800065The purpose of this study is to define the effects of wire electrical discharge machining (WEDM) process parameters on surface roughness for Al/B4Cp metal matrix composites (MMCs) having different amounts of reinforcement particle (3, 6, and 12 wt.%). Totally nine experiments were performed according to the experimental design method conducted by Taguchi L-9 orthogonal array on Al/B4Cp MMC samples to determine the effect of WEDM process parameters on the surface roughness. The particle reinforcement amount (wt.%) is the most dominant factor (60.69%) on the surface roughness and it is followed by pulse on time (36.28%) and wire feed (1.49%), respectively. The surface roughness value taken from confirmation experiments and predicted value is 5.26 mu m, 5.37 mu m respectively.Gebze Inst Technol, Izmir Katip Celebi Univ, Istanbul Kultur Univ, Doga Nanobiotech Inc, Terra Lab, Inc, LOT Oriel Grp Europe, Redoks Inc, Edinburgh Instruments, Anamed & Analitik Grp, NanoMagnet Instruments Ltd, Maney Publishin