Aluminum Welding Research Articles

Friction stir welding on temperature field for aluminum alloy based on combined HSM

A combined heat source model (HSM) is a new technology to resolve the welding problem of aluminum alloy in the friction stir welding (FSW) process. It authenticates advantage is solid-phase welding technology for magnesium, aluminum, and other low melting point alloy welding. Temperature field analysis is the prerequisite for improving the welding quality, welding metallurgy, and mechanical analysis. An accurate grasp of the temperature field distribution on the FSW process plays a vital role. In this research, the temperature field of FSW for 6005 aluminum alloy is simulated and analyzed by SYSWELD software. Then the simulation results were verified by experimental results. First of all, the finite element simulation and theoretical analysis were carried out for the FSW process. Then finite element model was established by using the SYSWELD software. And the temperature field of the FSW process was established by grid partitioning, HSM setting, and subsequent observation. The numerical simulation method is used to analyze the temperature field of the FSW process. Finally, the simulation results are verified and calibrated by the thermocouple temperature test. The influence of different welding parameters (Welding Speed and Rotational Speed) on the temperature field is evaluated by the thermal field curves analysis and some particular nodes analysis of the target area.

Experimental analysis of friction stir welded of dissimilar aluminium 6061 and Titanium TC4 alloys using Response Surface Methodology (RSM)

In this present study, aluminium and its alloys are welded using friction stir welding technique (FSW) and the experimental work is ameliorated by Response Surface Methodology (RSM) and Artificial Neural Networking (ANN). FSW is exploited predominantly in many industries for welding of aluminium and its alloys. Moreover, the mechanical properties of the welded zone are prompted by the quality of the weld and the welding parameters. RSM and ANN are the various techniques are deployed to validate the tensile strength (TS) based on the welding parameters. Back propagation (BP) is instigated for the prediction of the error such as (Mean Absolute Error) MAE. Three different tools have been exploited for welding of aluminium alloys and comparison is also effectuated using ANN and RSM. In these techniques, the TS of the predicted value is consequential in the range of 202.64Mpa to 219.30Mpa at high Rotational Speed (RS). Also, the percentage of error is less than 1.5 % in ANN which ascertains the superior TS in design space.

Effect of work material combination and welding speed in dissimilar friction stir welding of aluminium to steel

Effect of welding speed on strength and ductility of the friction stir butt welded assemblies formed with two different combinations of sheet metals viz. AA 1100 – AISI 304 and AA 7075 – AISI 304 was investigated. The experiments were conducted on a 30 kN CNC friction stir welding machine with the help of a tool made of H13 steel having a tapered cylindrical pin. Finite element simulation of approximated heat transfer model was conducted to check the effect of tool offset on distribution of temperature in aluminium and steel. Ultimate tensile strength and percentage elongation at break of weld metals decreased with the rise of welding speed. Microstructural characterization was carried out to investigate the reasons of poor joint efficiency obtained.

Mathematical modelling to predict angular distortion in MIG welding of aluminium 6063 plates

Goal of the present investigation is to see how different operational factors such as voltage, weld speed, nozzle plate distance (NPD), torch angle, and wire feed rate affect the angular distortion of welds on aluminium 6063 plates. This grade of aluminium has extensive applications ranging from industrial to domestic usage. A structured set of experiments were carried out using the statistical approach of design of experiments. The CCRD (central composite rotatable design) approach developed a mathematical model relating the response, angular distortion and input parameters. The adequacy of this model was checked by using the ANOVA technique. For studying the results graphically, RSM (Response Surface Methodology) is applied. The developed model optimises the input parameters to minimise the resultant angular distortion. Such a prediction of angular distortion before welding could be of significant help in improving and maintaining weld joint quality.

Analysis of bend angle variation in aluminium – copper friction welding in the presence and absence of nickel interlayer

Friction welding of Aluminium with Copper without interlayer and with Nickel interlayer were performed. Friction welding parameters were Friction pressure, upset pressure and burn-off length. Three levels were chosen for each of these parameters and Taguchi analysis was done, with bend angle as the output parameter. Burn off length followed by friction pressure and upset pressure were found to be the significant parameters for friction welding without interlayer. Friction pressure followed by burn off length and upset pressure were found to be significant parameters for friction welding with Nickel interlayer. The results were analyzed and possible analysis for the results obtained have been given based on friction welding theory.

Effects of reduced ambient pressure on the OCT-based weld depth measurement signal in laser welding of aluminum and steel

For the process monitoring during laser deep penetration welding, optical coherence tomography (OCT) has emerged as a promising method for the in-situ measuring of the keyhole depth or, as a result, of the weld penetration depth. Prior research on this topic with steel substrates has shown that reducing the ambient pressure significantly improves the detectability of keyhole bottoms. In addition to OCT measurements, high-speed recordings of the process zone enable the evaluation of the keyhole opening behavior in this study. Bead-on-plate welds in steel demonstrate that the reduction of the ambient pressure improves the measurements unambiguity and decreases the average keyhole diameter while the keyhole opening stability seems to remain mainly unchanged. Therefore, it can be concluded that the higher measurement unambiguity at lower ambient pressure is not caused by a higher keyhole accessibility of the OCT probe beam but rather by changed conditions inside the keyhole. Experiments with aluminum substrates validated the beneficial effects of the reduced ambient pressure on the detectability of the keyhole bottom.

Vol4 num2-17 Influence of surface topography parameters on the structural adhesive of aluminum 7075 polishing by robot and TEPEX®

In the process of continuous improvement of manufacturing processes in the field of the automotive sector comes this study developed within the framework of the Ecovoss project. Its objective is based on substitution of aluminum welding operations with the option of adhesive operations with other types of materials such as polyamides or, in this case, a TEPEX® composite material (dynalite 202-c200 / 50% TYP 13). In this work we try to test the best texturing in the union of 7075 aluminum specimens manufactured by robotized polishing with ABB 6640 robot, with specimens in TEPEX® material cutted in order to have a surface for application of the adhesive product. It uses a structural adhesive film AF-163-2 from 3M, which must be applied with determined pressure and temperature. The tests carried out are based on the topographic measurement of the surfaces to be adhesively bonded with the Alicona interferometer and in the tests for cutting the adhesive bond. The expected results must provide the state conditions of the surfaces to optimize the adhesiveness of the materials studied.

Analysis of Eddy Current Testing Detection Ability to the Varied Longitudinal Cracks on Coated Weld Metal Tee Joint of 5083 Aluminum Ship Structure

Due to its service, crack sometimes occur on the coated 5083 aluminum weld metal. One method for finding crack under protective coating is by using eddy current testing (ECT). This method of nondestructive testing relies on a circular electrical path generated by the coils positioned just above the surface being examined. The purpose of this research is to analyze the sensitivity of ECT by using variety of crack dimensions on 5083 aluminum welded plate tee joint. Five test pieces, each 200 mm × 50 mm × 10 mm were used and each sample contain four cracks. Artificial cracks are fabricated using electrical discharge machining (EDM) with length and depth variations. Variations in crack length are 5.0 mm, 7.0 mm, 9.0 mm, and 15.0 mm, and variation in depth are 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm and 2.5 mm. Results obtained by the analysing height and average length of the crack signal indication are as follows: for 0.5 mm crack depth, the height of the crack signal is 5 mm; 1.0 mm depth is 11.75 mm; 1.5 mm depth is 19.75 mm; 2.0 mm depth is 26.5 mm and 2.5 mm depth is 31.25 mm. The degree of accuracy obtained for the detection of crack depth is 93.57%. For the detection of crack length, it is found that the measured average length of artificial cracks is 5 mm actual crack length has measured crack length of 6.32 mm; 7 mm actual crack length has measured crack length value of 7.18 mm; 9 mm actual crack length has a measured crack length value of 8.8 mm and 15 mm actual crack length has measured crack length of 14.48 mm. The degree of accuracy obtained for crack length detection is 91.31%.

An investigation on galvanic corrosion in frictionstir-welded AA 5083 aluminum alloy

Friction-stir welding (FSW) is a well-known solid-state technology for manufacturing high-quality aluminum welds. However, corrosion may become an issue due to the changes in the microstructure within the stir zone, perhaps creating a local galvanic couple. In this work, AA 5083-O aluminum plates were joined by FSW, and corrosion analyzes were undertaken. Therefore, corrosion behavior was investigated using an immersion test, open circuit potential (OCP), and zeroresistance ammeter (ZRA) measurements. The stirred material was found to be more resistant to pitting nucleation than the AA5083-O alloy base material on immersion test and OCP analyzes. Nevertheless, deeper pits were more significant in the stirred material. The ZRA test showed similar results for both regions, indicating this system’s low galvanic couple effect.

Influence of high frequency wobbling parameters on the weld quality of aluminium LBW

Currently available commercial remote laser beam welding (LBW) scanners allow a fast laser beam manipulation up to 1 KHz. In this work, wobbling (fast laser beam oscillation) was applied to weld aluminium alloy (5754) sheets of 1.6 mm thickness that are subjected to stamping processes later on. Influence of process parameters (laser power and speed, incidence angle and wobbling frequency and amplitude) in weld quality of T joint and edge lap joint configurations was studied. In T joint configuration, the use of 4047 wire filler metal of 1.2 mm of diameter was beneficial to avoid excessive undercuts and provide good penetration, weld shape and dimensions. Metallographic characterisation confirmed the absence of other defects such as lack of fusion, pores or cracks. In addition, wobbling led to optimal results without removing the protective coating of Ti/Zr from the sheets. Finally, mechanical characterisation for post-welding stamping suitability assessment of the welds was performed using shear and bending tests.

Rotary Friction Welding and Dissimilar Metal Joining of Aluminium and Stainless Steel Alloys

Friction welding (FW) is cost-effective, efficient, occupational safer and also eco-friendly in the absence of pollution, smoke, fume, and IR radiation during welding than conventional welding technologies. In this paper, the joining of aluminium AA6063 and steel SS304 dissimilar metal is explained with different faying surfaces and their SEM images of weld interface (WI), joint quality, tensile and yield strength, and the axial shortening are evaluated and compared. The joint quality factor of the experiment faying surface modification ‘E3’ was the maximum and about >100% with 236 MPa strength. The axial shortening was also less than 27 mm. The joint with hemispherical faying surface showed ‘U’ shaped WI and the joint with taper faying surface showed ‘V’ shape WI. So, the cross-sectional area of WI can be increased and the strength also increased. FW yields very high strength, low-stress weld with no weld defects such as porosity, voids etc. Here, in most cases, the joint strength is equal to base metal strength and it can avoid fastening to join two metals. FW has a minimal and narrow heat-affected zone (HAZ) of few microns size that differentiates FW from other welding techniques. The grain size of HAZ is directly proportional to the heat input during welding. During fusion welding of dissimilar materials, a lot of intermetallic compounds are formed at the weld interface and that will lead to poor strength of the welding because they have different chemical and mechanical qualities; therefore FW is a good choice for joining dissimilar metal rods as the intermetallic compounds can be reduced by FW.

On intermetallic phases formed during interdiffusion between aluminium alloys and stainless steel

One of the major challenges in welding of aluminium (Al) alloys and steels is the growth of brittle intermetallic phases, which depends on the thermomechanical processing history and the alloying elements. This work focuses on the intermetallic phase layers formed in roll bonded composites of Al alloy 6082 and stainless steel 316L after interdiffusion at temperatures in the range of 400 – 550 °C. Scanning and transmission electron microscopy characterisation showed that during interdiffusion, an αc-Al15(Fe,Cr,Mn)3Si2 phase layer formed first, before a discontinuous layer of τ1-FeNiAl9 formed at the Al-αc interface. Subsequently, a layer of θ-Fe4Al13 and τ11-Al5Fe2Si formed at the αc-steel interface, followed by a layer of η-Fe2Al5 with precipitates rich in Cr and Si or Ni. Nanoindentation and density functional theory calculations were performed to assess the mechanical properties of the formed phases. Miniature tensile testing confirmed that the bond strength decreased as the thicknesses of brittle phase layers increased. Further, it was found that the growth rate of the total intermetallic phase layer was significantly reduced for the high alloyed 6082-316L composites compared to unalloyed reference composites of 1080-S355. Altogether, this work provides insight into the combined effects of the alloying elements Si, Mn, Cr and Ni on the formation, growth and mechanical properties of the interfacial intermetallic phases in Al-steel joints.

Experimental studies on friction stir welding of aluminium alloy 5083 and prediction of temperature distribution using arbitrary Lagrangian–Eulerian-based finite element method

The present work focused on welding aluminium alloy 5083 using the friction stir welding process. Suitable welding process parameters were identified to fabricate a defect-free butt joint with a tool rotational speed of 1600 rpm, traverse speed of 20 mm/min and tilt angle of 3°. The microstructure at the nugget zone, thermo mechanically affected zone, heat-affected zone and base metal zone are examined. Mechanical properties of the weldment exhibited promising results with an average joint efficiency and hardness of 75.70% and 94.0 ± 5.0 vickers hardness, respectively. Fractography revealed ductile mode of failure in base and weld metal tensile samples. Furthermore, a 3D thermomechanical finite element model was utilized to simulate the friction stir welding process using the selected process parameters. Arbitrary Lagrangian–Eulerian-based model aided in predicting residual stress distributions and thermal history during the friction stir welding process.

Multi-sensing signals diagnosis and CNN-based detection of porosity defect during Al alloys laser welding

Porosity is one of the most common defects in laser welding of aluminum (Al) alloys, which seriously affects the welding quality. Online monitoring of porosity defect can provide guidance for the adjustment of process parameters to reduce the occurrence of porosity, which has attracted increasing attention. This paper presents a novel method for recognizing and detecting porosity defect during Al alloys laser welding based on multi-sensing signals diagnosis and deep learning. A multi-sensor platform, including a high-speed camera and a coherent light measurement system, is established to measure the keyhole 3D morphological characteristics. The obtained keyhole depth signal is processed by ensemble empirical mode decomposition (EEMD), and it is found that the change of keyhole depth can be used to recognize the regions where the pores appear. Besides, the sliding window algorithm is used to scan the keyhole opening morphological characteristic signals, followed by the wavelet packet transform (WPT) processing on a small segment of the signals in each window to obtain the time-frequency spectrum graphs. The messy spectrum graphs show that the keyhole opening fluctuates violently, indicating the formation of porosity in the corresponding location of the weld seam. A convolutional neural network (CNN) is constructed to identify the spectrum graphs, realizing the online detection of porosity. The results show that the proposed method has high accuracy and good reliability.

Effect of external magnetic field on resistance spot welding of aluminium to steel

Resistance spot welding of aluminium to steel with magnetic-assisted apparatus was performed for the first time to understand the metallurgical joining mechanism in the melt region and at the material interface. The electromagnetic force promoted circular motion of the molten metal and accelerated the diffusion of Fe atoms to the aluminium sheet, which induced finer grains, thinner intermetallic compound layers, reduced interface defects, and elevated hardness of the resulting aluminium nugget. Coach peel tests revealed that welds made with an external magnetic field presented enhanced strength and ductility compared to welds made with no external magnetic field. The enhanced strength and ductility resulted in a transition of the fracture behaviour from brittle interfacial mode to ductile button pullout mode, and increased the peak load and the energy absorption by 90% and 1327%, respectively.

Fatigue improvement of aluminium welds by means of deep rolling and diamond burnishing

Deep rolling is an industrially widely established mechanical surface treatment process for the modification of roughness and fatigue resistance. However, the process has not been considered as a potential method for the mechanical post welded treatment of welded joints yet. Even, the potential of deep rolling for increasing the fatigue strength is comparably well-known in the case of non-welded components. Therefore, the effect of deep rolling (hydrostatic mounted tool) and diamond burnishing (mechanical mounted tool) to increase the fatigue strength of butt joints was approved in this work for aluminium alloy AlMg4,5Mn0,7 (EN AW 5083). For this purpose, fatigue tests under full tensile loading were performed in as-welded and deep rolled, burnished and ultrasonic impact treated conditions. Different residual stress states as well as work hardening states are determined in deep rolled and burnished condition. However, similar and significant fatigue life improvement was determined for both processes.

Mechanical Properties of Aluminum 5083 Alloy GMA Welds with Different Magnesium and Manganese Content of Filler Wires

Gas metal arc welding of aluminum 5083 alloys was performed using three new welding wires with different magnesium and manganese contents and compared with commercial aluminum 5183 alloy filler wire. To investigate the effect of magnesium and manganese contents on the mechanical properties of welds, mechanical properties were evaluated through tensile strength, bending, and microhardness tests. In addition, the microstructure and chemical composition were analyzed to compare the differences between each weld. The tensile strengths of welds using aluminum alloy filler wires with a magnesium content of 7.33 wt.% (W1) and 6.38 wt.% (W2), respectively, were similar. The tensile strength and hardness of welds using wires with a similar magnesium content, but a different manganese content of 0.004 wt.% (W2) and 0.46 wt.% (W3), respectively, were higher in the wire with a high manganese content. Through various mechanical and microstructural property analyses, when the magnesium content of the filler wire was 6 wt.% or more, the manganese content, rather than the magnesium content, had a dominant effect on the strengthening of the weld.

Laser pressure welding of dissimilar aluminium and copper: microstructure and mechanical property

In this work, laser pressure welding of dissimilar aluminium and copper was conducted at a high welding speed of 15 m min−1. One-micron intermetallic compounds (IMCs) layer with heterogeneous dual-phases (copper and γ-Al4Cu9 phases) laminates in the joint interface were observed by transmission electron microscopy. The results showed that the combination of two joining mechanisms led to improved mechanical property, namely the mechanical interlocking due to the curved interface and the metallurgical bonding by the presence of the thin IMCs layer with heterogeneous laminates. The tensile shear force and the shear strength of the joint reached 2055 N and 111.94 MPa, respectively. The present study provides a more efficient method to join dissimilar aluminium and copper.

Effect of tungsten mesh interlayer on microstructure and mechanical performance of A6061/Ti6Al4V dissimilar joints

A novel method of laser welding-brazing A6061/Ti6Al4V with the assistance of a tungsten mesh interlayer was proposed. The spreading and wetting abilities of the molten aluminum on the Ti6Al4V surface were improved by the addition of the tungsten mesh. Al5(Ti, W) and Al18Mg3W2 were observed as second phases in the aluminum weld, which was a benefit to refine the aluminum grains and improve the mechanical properties of the aluminum weld. The Al3(Ti, W) layer and the (Al, Si)3Ti layer were observed at the Ti/Al interface. W and Si atoms substituted Ti and Al atoms in Al3Ti, respectively. W element distributed unevenly in the Al3(Ti, W) layer and segregated at the grain boundaries of the Al3(Ti, W) phases. D022-Al3(Ti, W) was transformed into L12-Al3(Ti, W) at the grain boundaries resulting from the segregation. The c/a value of the (Al, Si)3Ti crystal lattice was higher than that of Al3Ti. Nanohardness and elastic modulus of the (Al, Si)3Ti phase were higher than those of the Al3(Ti, W) phase. The tensile shear capacity and ductility of the A6061/Ti6Al4V joints with tungsten mesh were better than those of the joints without tungsten mesh at the same welding parameters.

Simulation of Friction Stir Spot Welding of Copper and Aluminium During Plunging Phase

Simulation is limited and remains briefly addressed in the literature of friction stir spot welding (FSSW) process in joining dissimilar copper and aluminium. Thus, this study simulated the FSSW process of copper and aluminium to investigate the peak temperature during the plunging phase produced by all possible combinations of levels for tool rotational speed, plunge rate, and plunge depth according to the full factorial design. The modeling was established by Coupled Eulerian-Lagrangian (CEL) model and ‘dynamic, temperature-displacement, explicit’ analysis. The highest peak temperature of 994.4 oC was produced by 2400 rpm rotational speed, 100 mm/min plunge rate, and 1.6 mm plunge depth. The combination was suggested to be the optimum welding parameters in joining copper to aluminium as sufficient heat input was essential to soften the area around the welding tool and adequately plasticize the material. Three sets of confirmation tests presented consistent responses with a mean peak temperature of 994.4 °C, which validated that the response produced by the suggested optimum welding parameters was reliable. The statistical result reported that the variability in the factors could explain 84.12% of the variability in the response. However, only the rotational speed and plunge depth were statistically significant. The residual plots showed that the regression line model was valid.