Welded Aluminum Alloy Research Articles

Effect of processing sequences in multi-pass friction stir processing on microstructure, microtexture and microhardness of 6063 aluminum alloy

ABSTRACT Single and double direction stir processing sequences were employed and investigated by fixing all other FSP parameters. Optical microscopy (OM) was utilised to assess the size and geometry of the processed zone. EBSD was also employed to evaluate the microstructure and microtexture development in different regions of the processed zones. In addition, Vickers microhardness measurements were made to evaluate the hardness evolution across the processed zone for the two processing sequences. The results show that using a single direction processing sequence is preferable due to better grain refinement, mainly in all regions of the processed samples. Gradual improvement was observed in microhardness with each additional pass, stronger refinement, and homogeneous grains in the processed regions (stir and overlapping zones). In the first pass’s stir zone (SZ), the microhardness is approximately 42.5Hv, while it increases to an average of 43.4Hv in SZ2 of the second pass and 44.3Hv in SZ3 of the third pass. Furthermore, more resistance to plastic deformation (slip) and lower intensity of heat distribution when compared to the double direction. Therefore, the application of a single direction processing sequence can be beneficial in the welding of such aluminium alloys.

Coupling effect of dynamic power and oscillation path on butt weld formation and melt flow behavior during aluminum alloys

The influence of the coupling effect between dynamic power and oscillation path on the formation of weld seams and the fluid behavior of the molten pool during laser welding of 5A06 aluminum alloy was investigated through numerical simulation and experimentation. Three power modes were compared in the experiments: equal power (EP), delayed dynamic power (D-DP), and non-delayed dynamic power (ND-DP). The experimental results show that both D-DP and ND-DP modes are favorable to improve the mechanical properties. Among them, the joints formed under the D-DP mode exhibit the best mechanical properties, with an average tensile strength reaching ≈ 99.1% of the base material, which is an increase of ≈ 35.3% and ≈ 5.6% compared to the EP and ND-DP modes, respectively. Numerical simulation results indicate that the D-DP mode effectively mitigates the average flow velocity of the molten pool, reduces the collision effects between liquid flows, suppresses the impact of fluid on the keyhole walls, and improves the stability of the keyhole and the welding process, thereby enhancing the mechanical properties of the joints.

Enhanced inertia friction welding of aluminum alloy and high-strength steel using CrCoNi interlayer: Microstructural and mechanical characterization

Enhanced inertia friction welding of aluminum alloy and high-strength steel using CrCoNi interlayer: Microstructural and mechanical characterization

Parametric characterization of the Christopher–James–Patterson model for crack propagation in welded zone of A7N01 Aluminum alloys

AbstractAluminum alloy is a widely used material in railway vehicle structures. In order to accurately analyze the crack propagation mechanism of Aluminum alloy welding structures and predict their crack propagation life, this study focuses on the A7N01 Aluminum alloy and proposes a full‐field strain solution method based on the least‐squares method. For the first time, digital image correlation (DIC) experimental measurements are combined with the finite element analysis method to determine the shape and size of the plastic zone at the crack tip of the compact tension (CT) specimen. And it also calculates the crack propagation driving force parameters of the Christopher–James–Patterson (CJP) model using traditional crack propagation driving parameters. The research results revealed that the plastic zone at the crack tip captured by DIC experiments is in good agreement with the finite element simulation results. Additionally, the crack growth rate curve of the A7N01 Aluminum alloy, fitted based on the CJP model, is insensitive to the stress ratio. The results offer an effective approach to utilizing the da/dN‐∆KCJP curve in analyzing A7N01 Aluminum alloy and welded structural failures, broadening the scope of engineering applications for the CJP model.

Information Retrieval in Friction Stir Welding of Aluminum Alloys by using Natural Language Processing based Algorithms

Information Retrieval in Friction Stir Welding of Aluminum Alloys by using Natural Language Processing based Algorithms

Effect of swinging laser on porosity, microstructure, and mechanical properties of laser welded aluminum alloy joints with different lap forms

Oscillating and conventional linear laser welding were conducted to enhance the bonding strength of dissimilar aluminum alloys. The effect of lap joint configuration on porosity, microstructure, and mechanical properties of laser-welded dissimilar aluminum alloy joints was investigated. It was found that the solidification rate of the melt pool was the dominant factor in the difference in porosity for oscillating laser-welded joints with different lap joint configurations. The main precipitated phase in welds with different lap joint configurations was eutectic Si, and the proportion of eutectic Si was higher in oscillating laser welds than in linear laser welds. The elemental distribution in oscillating laser welds was more uniform. The strengthening mechanism for tensile shear strength of oscillating laser welded lap joints was analyzed. The improved tensile shear strength and elongation were attributed to the reduced porosity and solid solution strengthening for the oscillating laser welding. The tensile strengths of the two lap types of oscillating laser welded joints increased by 25.1 MPa and 34.5 MPa, and the elongation increased by 0.7% and 4.5%.

Research on ultrasonic-stationary shoulder assisted friction stir lap welding of thermoplastic polymer and aluminum alloy

Friction stir lap welding (FSLW) has advantages on obtaining dissimilar upper polymer and lower aluminum materials joint (polymer/Al joint), and how to heighten the bearing capacity of polymer/Al joint as much as possible is greatly meaningful for the manufacturing industries. In this study, choosing dissimilar polyamide 6 (PA 6) polymer and 6061-T6 aluminum alloy materials as research object, traditional FSLW, stationary shoulder assisted FSLW (SSFSLW) and ultrasonic-stationary shoulder assisted FSLW (U-SSFSLW) processes were compared to understand the mechanism of ultrasonic enhancement on the polymer/Al joint. Firstly, the surface morphologies were studied. Then the analyses of micro/macro-structures, mechanical properties and fracture features were carried out by optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and tensile tests. Results showed that the lap shear failure load of polymer/Al joint by U-SSFSLW reached 1502 N from 814 N by traditional FSLW, because the addition of ultrasonic avoided the bulged-nodule structures on top surface and the cavity defect in stir zone (SZ), broke the Al anchor in upper plate, enlarge the width of SZ in lower plate, and made the deeper micro-pits and larger dents at the interface between SZ bottom and lower plate. The U-SSFSLW process provides an effective way to fabricate the high-strength hybrid joint of dissimilar upper polymer and lower Al materials.

Electron Beam Welding of Copper and Aluminum Alloy with Magnetron Sputtered Titanium Filler

In this work, the results from the electron beam welding of copper and Al6082T6 aluminum alloy with a titanium filler are presented. The influence of the filler on the structure and mechanical properties of the welded joint is studied in comparison with one without filler. The X-ray diffraction (XRD) method was used to obtain the phase composition of the welded joints. Scanning electron microscopy (SEM) was used for the study of the microstructure of the welds. Energy-dispersive X-ray spectroscopy (EDX) was applied to investigate the chemical composition. The mechanical properties were studied by means of microhardness measurements and tensile tests. A three-phase structure was obtained in the fusion zone consisting of an aluminum matrix, an intermetallic compound CuAl2, and pure copper. The application of Ti filler significantly decreased the amount of molten copper introduced in the molten pool and the number of intermetallic compounds (IMCs). This improved the strength of the joint; however, some quantity of IMCs was still present in the zone of fusion (FZ), which reflected the microhardness of the samples. The application of a titanium filler resulted in refining the electron beam weld’s structure. The finer structure and the reduced amount of the brittle intermetallic phases has led to an increase in the strength of the joint.

Microstructures and mechanical properties of laser-arc hybrid welded high-strength aluminum alloy through beam oscillation

High-frequency beam oscillation and synchronous wire-powder feeding were adopted for the laser-arc hybrid welding of a 2219-T6 high-strength aluminum alloy. Increasing the beam oscillation frequency from 0 to 250 Hz not only reduced the weld porosity from 2.64% to 0.16% but also promoted the transformation of columnar dendrites to fine equiaxed grains. In addition, the content of precipitated Al2CuMg increased with the refined size of the weld microstructure. The length of the columnar grains and the diameter of the equiaxed grains in the weld center were reduced by 40% and 50%, respectively. Owing to these improvements, the weld microhardness increased and became more uniform, and the variance decreased by 74%. The ultimate tensile strength and elongation of the welded joint reached 238.5 MPa and 4.3%, respectively, which were 26.5% and 105% higher than those of the non-oscillating hybrid weld, respectively. The weld tensile strength and the proportion of the area of the pore were negatively correlated. The porosity and microcracks of the welded joints were the main factors affecting the tensile strength of welded joints.

The analysis of microstructure evolution process considering the dynamic solidification conditions and flow field in the oscillating laser welding of aluminum alloy

The oscillating laser welding (OLW) can improve the weld microstructure and the mechanical properties of the welded joints, which greatly improves the quality of laser welding. In this paper, a macro-micro coupling model for investigating the microstructure evolution process in the OLW of 6061 aluminum alloy is developed. The dynamic solidification conditions (SCs) and flow field are considered in the model. The microstructure evolution process under the effect of the oscillating laser beam is analyzed and discussed in detail based on the calculated results. The obtained weld cross section and microstructure morphology results agree well with the experimental results, which proves the validity of the developed model. It is found that the microstructure morphology is significantly influenced by the dynamic temperature gradient (TG) and solidification rate (SR). The solute concentration distribution is changed by the flow field, which affects the microstructure evolution process. The results demonstrate that the developed model is efficient for refining weld microstructure and hence improving mechanical properties of the welded joints.

Investigation of Microstructural and Mechanical Characteristics of Friction Stir Welded Aluminum Alloy 7075-t6

Investigation of Microstructural and Mechanical Characteristics of Friction Stir Welded Aluminum Alloy 7075-t6

A Comprehensive Review on the Impact of Reinforced Nanoparticles in Friction Stir Welded Aluminium Alloys: An Analysis of Process Parameters and Mechanical Properties

A Comprehensive Review on the Impact of Reinforced Nanoparticles in Friction Stir Welded Aluminium Alloys: An Analysis of Process Parameters and Mechanical Properties

Numerical and experimental study on spatter in oscillating laser-arc hybrid welding of aluminum alloy

Spatter serves as a crucial metric for assessing welding stability, with excessive spatter posing significant risks to weld quality, performance, and equipment integrity while also impacting the environment adversely. In oscillating laser-arc hybrid welding (O-LAHW), the spatter exhibits a distinct pattern: an initial sharp decline followed by a gradual increase as oscillation speed rises. Existing research struggles to fully explain this trend due to challenges in developing a precise numerical spatter model. This paper introduces a novel heat flow labeling model and establishes an O-LAHW spatter validation model with 90 % accuracy based on it. Combined with hydrodynamics, this model explores the mechanisms behind spatter formation and suppression based on laser beam oscillation. Firstly, high-speed photography and numerical analysis reveal a third type of spattering in O-LAHW, distinct from spatter caused by keyhole collapse and droplet impact—spatter occurs when liquid metal is expelled from the melt pool due to laser beam oscillation. Secondly, hydrodynamic insights show that laser beam oscillation significantly reduces steam-induced driving force and metal vapor resistance to droplets. Consequently, as oscillation speed increases, the prevalence of the first two spatter types diminishes while the third type becomes dominant. Large-particle spatters decrease while small-particle spatters increase. Finally, by analyzing spatter statistics across various oscillating parameters, we observe a competitive mechanism among the three types of spatters. In non-oscillating welding, Type I spatter predominates; under low-frequency oscillation, Type II gains dominance; in high-frequency oscillation, Type III takes over. Optimal spatter reduction occurs at low-frequency oscillation, achieving a 27.1 % decrease compared to non-oscillating conditions.

Integrating Numerical Simulation and Experimental Validation to Analyze Temperature Distribution in Friction Stir Welding of Dissimilar Aluminum Alloy

This study explores the temperature distribution in Aluminum alloys, specifically AA2024 T351 and AA6351 T6, during friction stir welding (FSW). Utilizing COMSOL Multiphysics software, the research investigates FSW at rotational speeds of 800, 1200, and 1600 rpm, while maintaining a constant welding speed (35 mm/min) and axial force (3 kN). The simulation incorporates temperature-dependent material properties. The findings reveal that the maximum temperature occurs at the upper part of the stir zone for both alloys. Experimental validation demonstrates excellent agreement with the simulated temperature distribution, reaffirming the accuracy of the COMSOL Multiphysics model.

A comparative study on mechanical properties between linear and zigzag pattern holes reinforced with tialite particles during FSW of AA6082 alloy

In this study, a comparison between linear and zigzag patterned holes is carried out where the holes in the pattern are incorporated with tialite/aluminium titanate (Al2TiO5) particles at the weldment region during friction stir welding of AA6082-T6 aluminium alloy. Different values of tool rotational speed (TRS: 1000, 1200 and 1400 rpm) and welding speed (WS: 35, 40 and 45 mm/min) are considered for the fabrication of joints by both patterns. Visually, no defects are found in all the welded samples. Microstructural analysis has proven that the uniform distribution of particles along the weld region can be obtained by using a zigzag pattern. Maximum hardness is found in the stir zone (SZ), whereas minimum hardness is found in the heat-affected zone (HAZ) for all the samples. The maximum ultimate tensile strength (UTS: 268 MPa), maximum yield strength (YS: 200 MPa) and relatively higher elongation (EL: 7.89%) are exhibited by the Z5 sample, whereas minimum UTS (206 MPa) and minimum YS (142 MPa) was exhibited by L3 and Z7 samples, respectively.

Arc behavior and droplet transfer characteristics during oscillating laser-arc hybrid welding of 2024 Al alloy based on Zr-core-Al-shell wire

A novel zirconium (Zr)-core-aluminum (Al)-shell wire (ZCASW) combined with oscillating laser-arc hybrid welding (O-LAHW) process was employed for the welding of aluminum alloy 2024 (AA2024). The arc stability and characteristics, droplet transfer behavior and weld formation were systematically investigated. The results show that electrical signal waveform determines wire feeding rate, which affects the welding stability and weld quality. The increment in wire feeding rate increases magnetic field intensity and narrows arc cross-sectional area, which leads to arc contraction. The oscillating laser increases arc width and arc area, thereby expanding the conductive channel and greatly improving conductive ability of hybrid plasma, which promotes interactions between plasmas and helps to droplet transfer. Meanwhile, owing to the melting points differences between Zr wire and Al wire in ZCASW filler material, the melting rate of outer Al wire is larger than that of central Zr wire during welding, thereby resulting in two kinds of droplet transfer modes, and electromagnetic force and metal vapor reaction force strongly influence droplet transfer behavior. The oscillating laser improves the weld quality, which is deteriorated due to the appearance of spatters as wire feeding rate increases. When 1 m/min wire feeding rate is selected, a perfect formation is obtained. The current study offers insight into the formation mechanism of high-quality weld and welding stability during O-LAHW of AA2024 combined with ZCASW filler material.

Improving the corrosion resistance of aluminum alloy welds through powder-ball combined ultrasonic shot peening

Aluminum alloy 5052 is used extensively in various industries, including aerospace, shipbuilding, and automotive manufacturing. Components made from this alloy often require welding treatments; however, in marine environments, these welds are susceptible to corrosion, which affects their durability and service life. In this study, power-ball combined ultrasonic shot peening (USSP) was used for surface-strengthening 5052 aluminum alloy welds. The resulting surface characteristics and corrosion resistance were examined, and the compared to the untreated sample, the USSP-treated sample showed a shift in the stress state from residual tensile stress (31.4 MPa) to residual compressive stress (−257.5 MPa). Immersion and electrochemical corrosion experiments confirmed that the formation of residual compressive stress and a gradient structure on the surface enhanced the corrosion resistance, which was substantiated by detailed characterization. The corrosion rate of the treated aluminum alloy weld sample (7.18 μm/year) decreased by 72.90 % compared with that of the untreated sample. The study findings indicate that the powder ball combined USSP is a potential method for improving the corrosion resistance of aluminum alloy welds in marine environments.

Electrode life evaluation for varied electrode material composition and geometry in resistance spot welding of aluminum alloys

Electrode life evaluation for varied electrode material composition and geometry in resistance spot welding of aluminum alloys

Influence of Process Parameters on Residual Stresses in Dissimilar Friction Stir Welding of Aluminum Alloys

Foreseeing how welded structures will behave requires careful consideration of the residual stresses that the friction stir welding (FSW) process introduces. These residual stresses can cause severe deformation and compromise the ability of friction stir welded structures to bear imposed external loads. This work uses a Sequentially Coupled Thermo-mechanical finite element simulation to quantitatively evaluate the influence of such residual stresses coming from the FSW process. This modelling method examines the thermal and post- weld stress distributions during the friction stir welding of dissimilar AA2024-T3 and AA5086-O alloys. The procedure entails an initial thermal analysis followed by a mechanical analysis to determine the distribution of residual stresses across the entire dissimilarly welded alloys. The study examined how alterations in FSW operational parameters, such as rotational and translational speeds, influence both the thermal conditions and residual stress distribution. The findings highlighted that both temperature and residual stress exhibited higher values on the retreating side of the specimen compared to the intended advancing side. As the tool rotational speed rose, the magnitude of longitudinal residual stress dropped, however it showed an increase with greater tool translational speeds. Moreover, the simulated outcomes demonstrate the substantial impact of welding fixtures on the profiles and magnitudes of residual stresses.

Influence of welding parameters and post weld heat treatment on mechanical, microstructures and corrosion behaviour of friction stir welded aluminium alloys

A study on how corrosion and mechanical characteristics of friction stir welded joints are affected by processing parameters employed during the welding and the post-weld heat treatment administered on the welded materials has been reported in this paper. This study specifically investigated the effects of variable parameters such as the tool rotational and welding speeds and the post-weld heat treatment on the mechanical and corrosion behaviour of the friction stir welded dissimilar 6101-T6 and 7075-T651 Aluminium Alloys. The welded samples were characterized by the evolving microstructure and mechanical characteristics. The results show that the tensile strength of the joints decreases from 154 MPa to 144 MPa when the rotational speed increases from 950 rpm to 1550 rpm. However, the tensile strength increases from 138 MPa to 154 MPa with an increase in the welding speed from 20 mm/min to 110 mm/min. This is due to high heat input at higher rotational speed which weakens the bonding strength at the joints. The corrosion behaviour was observed to differ at different parameters. The corrosion inhibition efficiency was highest at a rotational speed of 950 rpm, welding speed of 65 mm/min, and lowest at 950 rpm and 20 mm/min. It was observed that the Post-Weld Heat Treatment (PWHT) process enhanced the mechanical properties as a result of an improvement in the grain refinement but lowered the corrosion resistance. This study is significant as it informs the basis for the optimization of processing parameters and post weld heat treatment for dissimilar aluminium alloys for the grades considered in this study.