Welding Of Dissimilar Alloys Research Articles

Experimental investigation of FSW induced property changes in welded dissimilar Mg–Al–Zn alloys

Intense plastic deformation and intermixing during friction stir welding of dissimilar alloys may suppress the properties in welded zone. To suitably control these changes, careful study is required. Present research investigates microstructure, mechanical performance and corrosion behaviour at different rotational speeds in friction stir welded dissimilar AZ31–AZ91 Mg alloys. Very small cracks were present in welded zone due to formation of magnesium oxide (MgO). The EBSD analysis suggest more concentrated fibre texture at 1000 rpm tool rotational speed as compared to 700 rpm tool rotational speed in welded zone and the texture maximum intensity was 39.447 times of random distribution at tool rotational speed of 1000 rpm. The obtained maximum microhardness was 82 Hv at tool rotational speed of 700 rpm. The maximum values of tensile strength (234.86 ± 7.77 MPa) and flexural strength (350.89 ± 17.67 MPa) of welded samples were decreased as compared to base materials. The corrosion rate of welded samples was increased and corroded surface have some pits and corroded rings. The highest corrosion rate (2.1596 mm / year ) was obtained at 700 rpm. This experimental work suggests that in overall, sample welded at 1000 rpm tool rotational speed has better weld property.

Evaluating the Microhardness Profiles in Friction Stir Welding of Dissimilar Alloys

Abstract: Friction stir Welding (FSW) advancement is used generally in the utilization of present-day flying and vehicle industry for predominant fundamental mentioning. Such a joining technique is displayed to avoid serious twists and the made excess weights are exhibited as low when it is stood out from the traditional welding structure. In this research, focus on to identify the parameters that will provide the dissimiliar alloys of aluminium AA6061 and AA8011 with good microhardness properties. From the current study microhardness strength of dissimiliar alloys of aluminium varies with the rpm, feed rate and shoulder diameter of the tool. At 2000 rpm and 15mm/min welding speed strength of joints is low and at high rpm 2400 and welding speed 20mm/min micro hardness strength is always low but at a rotation speed of 2200 rpm and welding speed 20 mm/min maximum strength of the weld joint . Hence at high rotational speed rise in the temperature occurs and cause dissolution of precipitates which lowers the hardness and at low rotational speed less heat generation at the tool workpiece interface causing less refinement of grains which lower the hardness value. During tensile strength test fracture and cracks occurs at weld center line.

An embedded machine learning strategy for analyzing interfacial characteristics in impact welding of dissimilar alloys

ABSTRACT In this study, a novel embedded machine learning (ML) framework was employed to analyze interfacial characteristics in dissimilar-alloy impact welding. While keeping the substrates constant, i.e., stainless steel and Ti alloy, the influence of interlayer types on the resultant morphology of impact-welded bonds was also highlighted. The dataset was meticulously generated through numerical simulations, utilizing materials properties and processing parameters as primary inputs. These inputs were used to predict various interfacial features, including the extent of wave formation (L), specific welding zone area (S), average waveform amplitude (A), and maximum interface temperature (Tmax). Impressively, exceptional predictive capabilities were demonstrated by the ML model, with determination coefficients of 0.938, 0.924, 0.967, and 0.909 for S, L, A, and Tmax, respectively. Based on the results, strong dependencies between interfacial features and the weight functions of materials properties and processing parameters were unveiled. Intriguingly, as the weight function of materials properties for a specific output objective increased, a corresponding decrease in the weight function of processing parameter inputs was observed. These findings emphasize the complex connection between input parameters and output characteristics, revealing previously unexplored intricacies in the impact welding process, facilitated by our advanced ML methodology.

Experimental investigations on the position of plates in friction stir welding of dissimilar alloys

Friction Stir Welding (FSW) is a solid-state welding procedure that involves heating and stirring the surfaces of two metal components to cause them to fuse together. The paper aims to present the influence of the plate position in friction stir welding of dissimilar aluminum alloys, of the same family. Friction stir welding experiments are conducted on AA6061 and AA6082 for different plate positions. The results of mechanical and microstructural characterization reveal that AA6082 on the advancing side provides better strength due to the material properties, temperature developed, and distribution along and across the weldments.

A Review: Laser Welding of Dissimilar Materials (Al/Fe, Al/Ti, Al/Cu)-Methods and Techniques, Microstructure and Properties.

Modern structural engineering is impossible without the use of materials and structures with high strength and low specific weight. This work carries out a quantitative and qualitative analysis of articles for 2016–2021 on the topic of welding of dissimilar alloys. It is found that laser welding is most widely used for such metal pairs as Al/Fe, Al/Ti, and Al/Cu. The paper analyzes the influence of the basic techniques, methods, and means of laser welding of Al/Fe, Al/Ti, and Al/Cu on the mechanical properties and thickness of the intermetallic compound (IMC). When welding the lap joint or spike T-joint configuration of Al/Fe, it is preferable to melt the steel, which will be heated or melted, by the laser beam, and through thermal conduction, it will heat the aluminum. When welding the butt-welded joint of Al/Fe, the most preferable is to melt the aluminum by the laser beam (150–160 MPa). When welding the butt-welded joint of Al/Ti, it is possible to obtain the minimum IMC and maximum mechanical properties by offsetting the laser beam to aluminum. Whereas when the laser beam is offset to a titanium alloy, the mechanical properties are 40–50% lower than when the laser beam is offset to an aluminum alloy. When lap welding the Al/Cu joint, under the impact of the laser beam on the aluminum, using defocusing or wobbling (oscillation) of a laser beam, it is possible to increase the contact area of electrical conductivity with the tensile shear strength of 95–128 MPa.

Компьютерное моделирование сварки давлением образцов из гетерофазных никелевых сплавов через прослойку

Computer simulation of pressure welding of cylindrical workpieces through an interlayer was carried out using the DEFORM-2D software package in a two-dimensional formulation (axisymmetric deformation). Two combinations of materials to weld were considered: sample I — cylinders of heterophase nickel-based deformable superalloy EP975 in a coarse-grained state were welded through an interlayer of EP975 with a fine-grained microduplex structure; sample II — cylinders of dissimilar nickel-based alloys, one the deformable alloy EP975 in a coarse-grained state and the other an intermetallic alloy VKNA-25 with a single-crystal structure, were welded through an interlayer of EP975 alloy with a fine-grained microduplex structure. The welding process was carried out under isothermal conditions at a temperature of 1125°C and an initial strain rate of 10−4 s−1. The material characteristics were described by experimental curves obtained under uniaxial compression tests of alloys at the welding temperature. The Siebel friction model was used to describe the contact conditions on the surfaces to be welded. The friction coefficient was taken equal to 0.3. The distribution of equivalent, axial, radial, circumferential and shear components of stress and strain in the samples have been investigated. Analysis of the simulation results allowed one to conclude that, in comparison to welding of similar materials, during welding of dissimilar materials the values of the radial, axial and circumferential stresses increase. Radial and circumferential stresses in the material of the cylinders are tensile, while compressive stresses prevail in the material of the interlayer. Area with the maximum values of shear stresses in the region of contact between the cylinders and the interlayer also increases. In this case, axial, radial and circumferential strains decrease in a cylinder made from a material with higher strength, the overall level of shear strain does not change, and on the reciprocal contact surface of the interlayer, the region of extension of maximum shear strain extends to the entire contact zone. Such a combination of factors allows one to conclude on more favorable pressure welding conditions for welding of dissimilar alloys in comparison with similar materials.

Fatigue Behavior of Linear Friction Welded Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.1Si Dissimilar Welds.

The use of joints fabricated from dissimilar titanium alloys allows the design of structures with local properties tailored to different service requirements. To develop welded structures for aerospace applications, particularly under critical loading, an understanding of the fatigue behavior is crucial, but remains limited, especially for solid-state technologies such as linear friction welding (LFW). This paper presents the fatigue behavior of dissimilar titanium alloys, Ti–6Al–4V (Ti64) and Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242), joined by LFW with the aim of characterizing the stress versus number of cycles to failure (S-N) curves in both the low- and high-cycle fatigue regimes. Prior to fatigue testing, metallurgical characterization of the dissimilar alloy welds indicated softening in the heat-affected zone due to the retention of metastable β, and the typical practice of stress relief annealing (SRA) for alleviating the residual stresses was effective also in transforming the metastable β to equilibrated levels of α + β phases and recovering the hardness. Thus, the dissimilar alloy joints were fatigue-tested in the SRA (750 °C for 2 h) condition and their low- and high-cycle fatigue behaviors were compared to those of the Ti64 and Ti6242 base metals (BMs). The low-cycle fatigue (LCF) behavior of the dissimilar Ti6242–Ti64 linear friction welds was characterized by relatively high maximum stress values (~ 900 to 1100 MPa) and, in the high-cycle fatigue (HCF) regime, the fatigue limit of 450 MPa at 107 cycles was just slightly higher than that of the Ti6242 BM (434 MPa) and the Ti64 BM (445 MPa). Fatigue failure of the dissimilar titanium alloy welds in the low-cycle and high-cycle regimes occurred, respectively, on the Ti64 and Ti6242 sides, roughly 3 ± 1 mm away from the weld center, and the transitioning was reasoned based on the microstructural characteristics of the BMs.

Laser welding of dissimilar alloys between high tensile steel and Inconel alloy for high temperature applications

ABSTRACT Inconel alloys are used for high temperature applications due to their excellent properties at elevated temperatures. The joining of Inconel alloys with other alloys is challenging due to the formation of cracks and interface microstructural segregation of alloying elements. In the present investigation Inconel 718 alloy was joined with high tensile steel using laser welding. In order to attain the quality joints, welding parameters were studied and identified their range. The microstructural characteristics of the welds at the fusion zone and heat-affected zone were analyzed. The microhardness variations across the fusion zone and other zones were observed. The mechanical properties of the joints were evaluated and found that the strength of the joints was related to laser power. The elemental analysis across the fusion zone was revealed the formation of segregation of the elements which has an influence on the strength of the joints.

Review on Friction Stir Processed TIG and Friction Stir Welded Dissimilar Alloy Joints

There is an increase in reducing the weight of structures through the use of aluminium alloys in different industries like aerospace, automotive, etc. This growing interest will lead towards using dissimilar aluminium alloys which will require welding. Currently, tungsten inert gas welding and friction stir welding are the well-known techniques suitable for joining dissimilar aluminium alloys. The welding of dissimilar alloys has its own dynamics which impact on the quality of the weld. This then suggests that there should be a process which can be used to improve the welds of dissimilar alloys post their production. Friction stir processing is viewed as one of the techniques that could be used to improve the mechanical properties of a material. This paper reports on the status and the advancement of friction stir welding, tungsten inert gas welding and the friction stir processing technique. It further looks at the variation use of friction stir processing on tungsten inert gas and friction stir welded joints with the purpose of identifying the knowledge gap.

Effect of Process Parameters on Microstructural and Mechanical Properties of Friction Stir Welded Dissimilar Aluminium Alloys AA 6061 and AA 7075

Frictions stir welding of dissimilar alloys are an efficient way in industrial applications. The effect of joining dissimilar alloys (AA6061-AA7075) has improves the mechanical strength of the welded joint. This work investigated the micro-hardness and mechanical properties of frictions stir welded dissimilar alloys. Aluminium alloy is heat treatable and may be subjected to either hot working or cold working. The heat treatment is followed by revolutionising and precipitation hardening. Microhardness was measured at various zones of the welded joints. The tensile properties of dissimilar joints are characterised. Tensile test results distributed the material flow and the stress-strain curve designates the mechanical strength of the frictions stir welding parameters. Cylindrical threaded profile has an important role among the other tool profiles. It contributes 93% to the overall efficiency. The high strength of 172 MPa was attained in the tool which is made up of cylindrical threaded pin profiled tool. This work inferred that the rotational speed, transverse speed, and D/d ratio for cylindrical threaded are considered more efficient. Maximum tensile strength could be obtained from the cylindrical threaded tool and it is comparatively high than other materials. Tensile and hardness measurement were done on this part of material characterisation.

Gas tungsten and shielded metal arc welding of stainless steel 310 and 304 grades over single and double ‘V’ butt joints

Shielded metal (SM) and Gas tungsten (GT) arc welding of two different sheet metal grades of stainless steel 310 and 304 of 3 mm thickness is attempted to produce a sound weld. The single and double ‘V’ butt joint is made to find its suitability for the anticipated use by producing the differences in strength in the welded joints. Two gas tungsten arc welded butt joint is produced by choosing the current as 110 A and voltage 19 V. Two shielded metal arc welded butt joints are produced when the current is kept as 80 A and voltage 19 V. The welded specimens are evaluated by dye penetrant inspection to identify the weld defects. From the inspection weld specimens are found defect free from porosity, cracks, lack of penetration and etc. The welded specimens are undergone for tensile testing and found as maximum 594 MPa in the case double ‘V’ shielded metal arc welded butt joint and 556 MPa in the case of double ‘V’ butt joint by the gas tungsten arc welding process. The research work will be suitable to choose effective welding technique for the butt welding of dissimilar alloys of stainless-steel grades 310 and 304 of 3 mm thickness with single or double ‘V’ edges for the practical use.

Tensile properties of dissimilar friction stir weld joints of Al-2024 and Al-7039 alloys

This manuscript deals with the dissimilar friction stir welding of 2024 and 7039 aluminum alloys, which are mainly used in aviation and automotive industry. A threaded truncated conical tool was used to carry out friction stir welding of dissimilar alloys. The weld joints were characterized by visual inspection, optical and scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction and tensile tests. Weld joints exhibited mixed structure comprising of both the base materials and heterogeneously distributed Cu and Zn in the weld region. The weld strength efficiency was found higher than the elongation efficiency. The low weight percentage of Cu and Zn in weld nugget zone can be attributed to dissolution of strengthening precipitates in this zone. Softening due to dissolution resulted in reduction of mechanical properties of dissimilar welds. The results suggest that 2024 and 7039 dissimilar alloys are friction stir weldable with promising properties.

Effect of Welding Parameters on the Corrosion Behavior of Dissimilar Alloy Welds of T6 AA6061 Al-Galvanized Mild Steel

Partial replacement of steel by Aluminium (Al) alloys is a promising approach adopted by automotive sector to improve fuel efficiency without compromising on the strength. However, this results in the generation of dissimilar welds of Al alloys and steel. Understanding the corrosion behavior of Al alloys–steel welds as a function of welding parameters is critical in the successful application of such alloys. The present study reports the intergranular corrosion behavior of T6 heat-treated AA6061 Al alloy-galvanized mild steel lap joints, welded by metal inert gas welding–brazing technique as a function of different welding parameters, viz. weld speed (4-6 m/min) and wire feed rate (0.8-0.9 m/min), following ASTM G 67-04. Weld characterization was performed by field emission scanning electron microscopy (FESEM), x-ray diffraction and nano-hardness measurement. Results indicate heavy dissolution and metal loss at the interface. A high volume fraction of Al-Fe intermetallics was precipitated at the weld interfaces, resulting in high hardness and higher localized corrosion. The thickness of Al-Fe intermetallic layer increased with increasing wire feed rate and lower weld speed which enhanced the severity of galvanic and intergranular corrosion.

Linear Friction Welding of Dissimilar Materials 316L Stainless Steel to Zircaloy-4

In the nuclear industry, there are a number of applications where the transition of stainless steel to Zircaloy is of technological importance. However, due to the differences in their properties there are considerable challenges associated with developing a joining process that will sufficiently limit the heat input and welding time—so as to minimize the extent of interaction at the joint interface and the resulting formation of intermetallic compounds—but still render a functional metallurgical bond between these two alloys. As such, linear friction welding, a solid-state joining technology, was selected in the present study to assess the feasibility of welding 316L stainless steel to Zircaloy-4. The dissimilar alloy welds were examined to evaluate their microstructural characteristics, microhardness evolution across the joint interface, static tensile properties, and fatigue behavior. Microstructural observations revealed a central intermixed region and, on the Zircaloy-4 side, dynamically recrystallized and thermomechanically affected zones were present. By contrast, deformation on the 316L stainless steel side was limited. In the intermixed region a drastic change in the composition was observed along with a local increase in hardness, which was attributed to the presence of intermetallic compounds, such as FeZr3 and Cr2Zr. The average yield (316 MPa) and ultimate tensile (421 MPa) strengths met the minimum strength properties of Zircaloy-4, but the elongation was relatively low (~ 2 pct). The tensile and fatigue fracture of the welds always occurred at the interface in the mode of partial cohesive failure.

Joining of dissimilar metals by diffusion bonding: Titanium alloy with aluminum

This paper presents a novel diffusion bonding process of commercially pure aluminum to Ti-6Al-4V alloy at 520, 560, 600 and 640 °C for 30, 45 and 60 minutes under argon gas shielding without the use of interlayer. The approach is to overcome the difficulties in fusion welding of dissimilar alloys. Diffusion bonding is a dissimilar metal welding process which can be applied to the materials without causing any physical deformations. Processed samples were metallographically prepared, optically examined followed by Vickers microhardness test and subjected to tensile test in order to determine joint strength. Scanning electron microscopy and energy dispersive spectroscopy were used in this work to investigate the compositional changes across the joint region. Elemental composition of the region has been successfully defined between titanium alloy and aluminum. The maximum tensile strength was obtained from the samples bonded at the highest temperatures of 600 and 640 °C.

Localized Corrosion Resistance of Dissimilar Aluminum Alloys Joined by Friction Stir Welding (FSW)

2XXX and 7XXX high strength aluminum alloys are the most used materials for structural parts of aircrafts due to their high strength/weight ratio. Their joining procedure is an engineering challenge since they present low weldability. Friction Stir Welding (FSW) is a joining technology developed in the early 90 ́s. It is a solid-state welding process, without the use of fillers or gas shield, that eliminates conventional welding defects and has been considered of great interest for application in the aircraft industry. FSW of aluminum alloys results in four regions of different microstructures, specifically: the base material (BM), the heat affected zone (HAZ), the thermo-mechanically affected zone (TMAZ), and the nugget zone (NZ). The complex microstructure of the weld region leads to higher susceptibility to localized corrosion as compared to the BM even when similar alloys are joined. The welding of dissimilar alloys in its turn results in even more complex microstructures as materials with intrinsically different composition, microstructures and electrochemical properties are put in close contact. Despite the great interest in FSW, up to now, only few corrosion studies have been carried out for characterization of the corrosion resistance of dissimilar Al alloys welded by FSW. The aim of this study is to investigate the corrosion behavior of aluminum alloy 2024-T3 (AA2024-T3) welded to aluminum alloy 7475-T761 (AA7475-T761) by FSW. The evaluation was performed in 0.01 mol.L-1 by means of open circuit potential measurements, polarization techniques and surface observation after corrosion tests.

Investigation of dissimilar metal welds by energy-resolved neutron imaging.

A nondestructive study of the internal structure and compositional gradient of dissimilar metal-alloy welds through energy-resolved neutron imaging is described in this paper. The ability of neutrons to penetrate thick metal objects (up to several cm) provides a unique possibility to examine samples which are opaque to other conventional techniques. The presence of Bragg edges in the measured neutron transmission spectra can be used to characterize the internal residual strain within the samples and some microstructural features, e.g. texture within the grains, while neutron resonance absorption provides the possibility to map the degree of uniformity in mixing of the participating alloys and intermetallic formation within the welds. In addition, voids and other defects can be revealed by the variation of neutron attenuation across the samples. This paper demonstrates the potential of neutron energy-resolved imaging to measure all these characteristics simultaneously in a single experiment with sub-mm spatial resolution. Two dissimilar alloy welds are used in this study: Al autogenously laser welded to steel, and Ti gas metal arc welded (GMAW) to stainless steel using Cu as a filler alloy. The cold metal transfer variant of the GMAW process was used in joining the Ti to the stainless steel in order to minimize the heat input. The distributions of the lattice parameter and texture variation in these welds as well as the presence of voids and defects in the melt region are mapped across the welds. The depth of the thermal front in the Al-steel weld is clearly resolved and could be used to optimize the welding process. A highly textured structure is revealed in the Ti to stainless steel joint where copper was used as a filler wire. The limited diffusion of Ti into the weld region is also verified by the resonance absorption.

Thermo-mechanical finite element model of friction stir welding of dissimilar alloys

A thermo-mechanical finite element model is developed based on Coupled Eulerian Lagrangian method to simulate the friction stir welding of dissimilar Al6061-T6 and Al5083-O aluminum alloys using different tool pin profiles. The model is validated using published measured temperatures and weld microstructure. The finite element results show that maximum temperatures at the weld joint were below the materials’ melting point. Placing the harder alloy (Al6061-T6) at advancing side led to a decrease in maximum process temperature and strain rate, but increased tool reaction loads. Featured tool pin produced better material mixing resulting in enhanced joint quality with reduced volumetric defects.

Friction Stir Welded Butt Joints of AA2024 T3 and AA7075 T6 Aluminum Alloys

The main objective of this research work is to investigate the feasibility of Friction Stir Welding (FSW) of AA7075 T6 and AA2024 T3 dissimilar aluminum alloys, with thickness ratio of 1.3, and to investigate the mechanical and structural properties of the weld. Since both AA2024 T3 and AA7075 T6 are not weldable by fusion welding processes, FSW process is used to weld both of these dissimilar alloys. Defect-free, tailor weld blanks were produced on the plates of AA7075 T6 and AA 2024 T3 having thickness of 6.5mm and 5mm respectively. The process parameters employed in this study include the tool rotation and travel speeds. The FSW tool employed in this study was made using AISI H13 tempered steel with square pin profile having pin diameter of 5mm, concavity at pin start of 1mm and pin length of 4.85mm. The welded plates have been characterized for their mechanical and metallurgical properties. The effects of tool rotational speed and the welding speed on the joint performance were discussed.

Effect of ultrasonic welding parameters on microstructure and mechanical properties of dissimilar joints

Ultrasonic spot welding has received significant attention during past few years due to their suitable applications in comparison to conventional fusion welding techniques. Fusion welding of dissimilar Aluminum and Stainless steel alloys is always a challenging task because of poor control on grain size and formation of undesirable brittle intermetallic compounds in the weld metal, which have deleterious effect on mechanical properties. In the past, welding of dissimilar alloys has been performed using electron beam welding, laser beam welding and friction stir spot welding, resistance spot welding, etc. However, little work has been reported on dissimilar welding of Aluminum and Stainless steel alloys using ultrasonic spot welding. The objective of the present work is to optimize ultrasonic spot welding parameters for joining 3003 Aluminum alloy with 304 Stainless steel. Welding was performed at various clamping pressures (i.e. 30, 40, 50 and 60psi) and energy levels for investigating its effect on microstructure, mechanical properties and bond quality of the weld. Different levels of weld quality i.e. ‘under weld’, ‘good weld’ and ‘overweld’ were identified at various welding parameters using physical attributes. The weld specimens prepared with energy 125 and 150J showed the maximum bond strength and were rated as “good” weld. It was also revealed that for a good quality weld, the maximum tensile strength is achieved once a reasonable amount of bond density and material thinning (required for the formation of metallurgical bonds) is attained.