Joining Of Different Materials Research Articles

Interfacial analysis by optical monitoring of layer level multi-material parts fabricated via Powder Bed Fusion–Laser Beam

This experimental work aims to contribute to the development of Powder Bed Fusion–Laser Beam (PBF-LB) processes for the fabrication of multi-material structures by studying the interfacial characteristics using an off-axis optical monitoring system and relating in-situ results with metallurgical and mechanical properties of built parts. The study was developed employing an innovative approach for intralayer multi-material fabrication by PBF-LB, based on the use of a partitioning system in the powder chamber.Image analysis was used to extrapolate information needed to describe possible contamination effects between powders, the size of the interface and the presence of metallurgical defects.Chemical, metallographic and statistical analyses were also carried out to study the interface between the two materials of the samples and to support the results from optical monitoring.The results showed that the optical monitoring system enables real-time verification of the required quality parameters during the joining of different materials with PBF-LB processes.

Enhancement of joint strength of dissimilar aluminum/polymer hybrid joints by friction stir spot welding by surface textures

The joining of different materials, particularly metals and polymers, is exceptionally challenging due to the necessity of producing lightweight hybrid structures in the automotive, aeronautics, and shipbuilding industries. In this research, an attempt was made to fabricate hybrid joints between aluminum alloy 5052-H32 and polycarbonate. The weld joint was made using friction stir spot welding. Response surface methodology was used to optimize the working process parameters. In addition, laser presurface treatment techniques were used to compare the joint’s performance. The mechanical and metallurgical findings demonstrate that these welds were effectively bonded together. Chemical adhesion was found to be the bonding mechanism between these dissimilar materials. The maximum tensile shear value obtained was 19.02 MPa at a tool rotational speed (TRS) of 1381 rpm, dwell time (DT) of 10 sec, and plunge depth (PD) of 0.9 mm in friction stir spot welding. Interestingly, the maximum joint strength of 23.37 MPa was obtained with the influence of laser-based presurface treatment at the same optimized welding parameters. This technology offers a feasible alternative to mechanical fastening and adhesive bonding for structural applications.

Investigations of Microstructure and Mechanical Properties of Lap Jointed Dissimilar Metals by Friction Stir Spot Welding Process

The joining of different materials is required for industrial application to utilize the hydride structures with attractive advantages such as superior strength to weight ratio, low cost, high tensile strength and less weight of the component. Specifically, Al-Cu composite material is widely used in foil conductors of a transformer, electrical connectors, foil windings in capacitors and tubes in heat exchangers. However, joining or spot welding the Al parts to Cu parts are significant challenge owing to variation in mechanical properties and chemical compositions of joining materials. In this present research work, the friction stir spot welded process (FSSWP) is carried out to join the Al and Cu materials. Further, microstructure and mechanical properties of friction stir spot welded specimens (FSSW) are studied at different tool rotational speeds likely from 1000rpm to 1500rpm. The microstructural study is carried out using scanning electron microscope images at the interface and overall welded region. The tensile strength of both single and double spot-welded specimens is analyzed using a universal tensile test machine. The output of this study states that the optimal tool rotational speed is 1500rpm for both single and double spot-welded specimens. Moreover, the double spot-welded specimen exhibits more tensile with a crack-free spot-welded surface than that of the single spot-welded specimen. The tensile strength double spot-welded specimen has a 6.8% higher strength than that of a single spot-welded specimen. Based on the present study, it is concluded that the double spot-welded specimen can be used for different industrial applications to replace Cu material with this Al-Cu material that gives added advantages to those components.

Investigation on clinch riveting process with different material combinations

Clinch riveting is a new joining process originating from clinching. The presence of rivets greatly enhances the shearing load of joints. However, conventional rivet is deformable, which may increase technological intricacy consequently. In this article, clinch riveting with rigid rivets was proposed, and the effects of sheet material combinations on the mechanical properties of joints were researched. Four sheet material combinations, involving two kinds of aluminum alloy (AA5052 and AA1060), were utilized to produce the clinch riveted joints. The joining quality was evaluated in four aspects: tensile load, shearing load, failure mode, and absorbed energy in shearing tests. Tensile and shearing tests were implemented to obtain the static load of joints. Results showed that both sheet materials and the geometrical parameters of joints were key factors determining the mechanical properties of joints. During the joining of different materials, the joint with a high-strength sheet on the top exhibited greater static load and absorbed energy than the joint with a low-strength sheet on the top. Neck fracture, button separation, and mixed failure could be observed in tensile tests. In shearing tests, all joints failed at the neck parts.

Microstructure and Fatigue Properties of Resistance Element Welded Joints of DP500 Steel and AW 5754 H22 Aluminum Alloy

The modern concept of lightweight design (LW) requires the application of different materials in one structure (multi-material structures). The structure of different materials has a good perspective for application in the automotive and aerospace industries but only if it is possible to achieve a quality joint between different materials. The most used technology for joining different materials in the automotive industry is Resistance spot welding (RSW). Due to different mechanical, physical, and chemical properties, the joining of different materials by RSW technology does not provide a quality joint, and accordingly, alternative technologies for joining different materials have emerged. Resistance element welding (REW) was developed to enable joint of different materials. This paper presents the welding of AW 5754 H22 Al alloy (1.0 mm-thick) and DP500 steel (1.5 mm-thick) using novel REW. The peak load, absorption energy, microstructure, microhardness and fatigue strength of the REW joint has been investigated. The joint of the same materials has been done also using conventional RSW to compare some results. The results that will be presented in this paper show that that REW can achieve reliable joining of the two materials at relatively low welding currents compared to RSW. Using REW process with a significantly lower welding current, satisfactory mechanical characteristics of the weld joint can be achieved, so peak load is between 2300–2500 N, displacement is between 2.5–3 mm and the absorption energy is between 3.3–5.7 J. REW joints showed fatigue strength with the fatigue limit of 882 N.

Development of a non-thermal atmospheric pressure plasma-assisted technology for the direct joining of metals with dissimilar materials

This work demonstrated the joining of SUS304 stainless steel to polycarbonate (PC) using an atmospheric pressure radio frequency (RF) plasma jet in conjunction with thermal press fitting. The tensile shear stress values of samples bonded after plasma treatment of both the SUS304 and PC were found to be higher than those of specimens in which only one or neither surface was exposed to the plasma. These results confirm that an atmospheric pressure RF plasma jet can be applied to the joining of different materials.

NDT studies and microstructure investigation on dissimilar materials joining by using FSW method

Recent research work is carried the joining of different materials of hardened steel, aluminum and titanium interface. The unique or comparable joining strategies are giving better execution of materials strength. High rotational speed and High manufacturing joining method is given good bonding contacts. The most extreme temperatures are Titanium and hardened steel materials range around 1600 °C. High-tension, Temperature and great speed locales are needed for the welding system. Titanium and tempered steels are covered 300 °C reaches to applied aluminum shower covering with steady tension. The reason for covering aluminum is great holding strength of titanium and hardened steel. Non Destructive testing results are checked and examined with the assistance of frictional joints. This exploratory work finishes four distinct trials of hardened steel, aluminum and titanium joints through various paces with constant manufacturing pressure. Hardened for titanium and tempered steel relations of 2100 °C and 60 MPa producing pressure, rubbing time 5 sec and grinding tension of 70 MPa. Rubbing welding tests are finished the materials surfaces and evaluated the assistance of contact behaviors.

Effects of Curie particle induced accelerated curing on thermo mechanical performance of 2K structural adhesives – Part I: Bulk properties

ABSTRACT Adhesive bonding represents a widely established manufacturing process, which offers many advantages such as joining of different materials while resulting in a more advantageous stress distribution when loaded. Compared to other, mainly mechanical, joining techniques, the long curing times of adhesives – sometimes up to days – represent a decisive disadvantage. After adhesive application, contractors have to maintain these times until components can be moved for further processing, or full load can be applied. Different methods are used to circumvent the problem of adhesive cure, and thus accelerate polymerisation, among others, microwave, UV or conventional oven curing. In addition to aforementioned methods, the use of electromagnetic induction represents a promising non-contact method for accelerated curing. With this method, bonded components are exposed to a high frequency (HF) electromagnetic field (EMF), which generates heat that is transmitted to the adhesives to be cured, and in turn speeds up polymerisation. If adherends, like for example wood, glass, or G-FRP, are not sensitive to EMF, so-called susceptors (e.g. meshes, fibres or particles) are introduced into the adhesives, which can be heated inductively. Curie particles (CP) represent a special type of susceptors, which can only be inductively heated up to their material specific Curie temperature (T c) above which heating automatically stops. Thus, a curing process is designed, which is independent from external temperature monitoring techniques and – at the same time – prevents the adhesives from overheating. The present study investigated the influences of inductive curing with CP on the bulk properties of a 2 K epoxy resin and a 2 K polyurethane using standardised specimen types: adhesive bulk (AB) and dynamic mechanical analysis (DMA) specimens. The authors showed with an experimental programme of 92 specimens that resulting thermo-mechanical bulk properties of the two investigated adhesives are fundamentally changed by application of the process.

Effect of input power and interfacial powder size on microwave joining of different materials: A review

The use of microwave energy for processing of different materials is gaining significant attention in today’s manufacturing industries. The microwave energy found to be applied in sintering, cladding, brazing, joining, casting and drilling of variety of materials. This paper is focused on the detailed review of the research works carried out on the effect of input power of microwave source and interfacial powder size on joint characteristics of different materials. It has been reported that majority of the isotropic to orthotropic materials can be joined using microwave heating source. The characteristics of the joints produced through microwave energy were studied by various researchers using mechano-metallurgical characterization techniques like tensile and hardness tests technique, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The characterization results found in different works are presented in the paper.

Adhesive-free joining and application for flexible devices - a review

Interface has been recognized for a long time as a part of materials such as surface and grain boundary in bulk in spite of the fact that interface gives decisive influences on the performance and durability of devices in practical use. Interface is also well known to have four principal performances and roles such as mechanical, electrical, magnetic and optical properties. Here, I will at first review the interface behavior with special emphasis on materials science and then introduce typical examples of case study. Mechanical behavior of interface can be attributed to joining of different materials in particularly at low temperature and intrinsic defects introduced in the process of joining caused by difference in thermal expansion. Defects thus introduced is known to result in work hardening of interface. Recently, an epoch-making method of joining to utilize water gas adsorption layer as an adhesive agent. This gas adsorption joining (GAJ) was demonstrated in cycloolefin polymer (COP) film and borosilicate glass system. Both surfaces were first modified by atmospheric pressure plasma, followed by close lamination to reaction distance and heated at about 100°C to result in the formation of a strong covalent bond for joining. Durability thus formed system was found to remain unchanged even after weathering test in 60°C, 95%RH for 2000 hrs. Joining mechanism can be explained in terms of an increase in density of functional molecules at the interface, followed by dehydration. Thickness of joining layer was confirmed by X-ray photoelectron spectroscopy and STEM and EELS to be 1∼2nm. Sealing performance of GAJ was examined by measuring Water Vapor Transmission Rate (WVTR) by MOCON system using joined PET films on which high barrier layer was coated. The WVTR of line sealing with 1 mm width and 1-2 nm thick was found to be better than 5 x 10−4 g/m2/day. Practical applications of thus developed GAJ for joining and sealing are now in progress for flexible film devices such as OLED display, solar cells, and healthcare devices. Finally, roles of interface in materials science in future will be critically discussed.

Manufacturing, high heat flux testing and post mortem analyses of a W-PIM mock-up

Abstract In the framework of the European material development programme for fusion power plants beyond the international thermonuclear experimental reactor (ITER), tungsten (W) is an attractive candidate as plasma facing material for future fusion reactors. The selection of tungsten is owing to its physical properties such as the high melting point of 3420 °C, the high strength and thermal conductivity, the low thermal expansion and low erosion rate. Disadvantages are the low ductility and fracture toughness at room temperature, low oxidation resistance, and the manufacturing by mechanical machining such as milling and turning, because it is extremely cost and time intensive. Powder Injection Molding (PIM) as near-net-shape technology allows the mass production of complex parts, the direct joining of different materials and the development and manufacturing of composite and prototype materials presenting an interesting alternative process route to conventional manufacturing technologies. With its high precision, the PIM process offers the advantage of reduced costs compared to conventional machining. Isotropic materials, good thermal shock resistance, and high shape complexity are typical properties of PIM tungsten. This contribution describes the fabrication of tungsten monoblocks, in particular for applications in divertor components, via PIM. The assembly to a component (mock-up) was done by Hot Radial Pressing (HRP). Furthermore, this component was characterized by High Heat Flux (HHF) tests at GLADIS and at JUDITH 2, and achieved 1300 cycles @ 20 MW/m². Post mortem analyses were performed quantifying and qualifying the occurring damage by metallographic and microscopical means. The crystallographic texture was analysed by EBSD measurements. No change in microstructure during testing was observed.

Investigations on tailored forming components as tribologically loaded machine elements

To fulfil future trends of machine elements, the surface and part properties need to be enhanced. To advance machine elements, the application of tailored forming technology offers new possibilities. With this approach, it is possible to design and manufacture machine elements consisting of two or more different metallic materials with improved performance and functionality specially adapted to their respective application. The process chain starts with the joining of different materials to multi-metal work pieces, which are subsequently formed close to the final contour. The properties of the joining zone can be improved by thermal and mechanical treatment accompanying the forming process. Exemplary multi-metal components with a boundary zone subjected to rolling contact fatigue were investigated. Thus, an axial bearing, a shaft with an integrated raceway, a bearing bushing/angular contact ball bearing and a bevel gear wheel were in the focus of this research. Here, the highly stressed areas are reinforced with a higher strength material, while the rest of the part consists of a lower grade material. In case of the shaft, the raceway acts like the inner ring of a bearing and should resist rolling contact fatigue and mechanical wear. The process route was set up and simulations regarding the fatigue life in dependence of the layer thickness of the material acting as raceway were performed. First fatigue tests were executed to prove the reliability of the described concept.

Considering the possibility of bonding utilizing cold sintering for ceramic adhesives

AbstractHere, we introduce a new bonding technique that enables the joining of different materials at low temperatures and provides a bond superior to that of polymer adhesives at high temperatures, in temperature ranges between 250°C and 500°C. This technique involves a low temperature sintering process that is termed the “Cold Sintering Process,” where a dielectric composite powder material is sintered to function as the adhesive between two other materials being bonded. In order to characterize and further discuss the potential of this new bonding methodology, which we call Cold Sintering Ceramic Bonding (CSCB), we demonstrate the initial mechanical characteristics of samples with sandwich structures of mesh/CSCB/mesh, including four‐point bending, micro‐indentation, and adhesion pull tests. Where appropriate, we compare mechanical properties against low and high temperature epoxies and demonstrate that the CSCB matches up competitively with the epoxies at low temperatures and remains strong at temperatures well above those where standard polymer adhesives fail. Transmission electron microscopy show a high quality interface between a stainless steel plate and the ceramic after the CSCB.

THE EFFECT OF WELD POSITION ON MECHANICAL PROPERTIES OF TMT ROD JOINED BY ARC WELDING

There are various welding processes for joining the materials. Arc welding is a prominent joining process in which two steel parts are joined by heat generated due to arc. Many researches have been carried out in joining of different materials by different welding techniques. Our research has been emphasized on TMT bars. A Thermo Mechanical Treated (TMT) bar is commonly used for making reinforced roofs and column of building. They are also used in for industrial purpose such as rock bolting in underground mines etc. Most of TMT bar’s joining process took place with arc welding. In this paper a study has been made for the effect of welding position on strength of joined rods. In this study four Nos. of samples were taken having different locations of welding. They were allowed to cool under ambient condition. The chemical composition of parent material and weld zone were checked and observed that weld zone have different chemical composition compared with parent material. The variations of hardness with respect to distance were also checked using Brinell hardness testing machine and it was found that firstly hardness decreases and then increases with increase in distance from weld centre. From microstructural examination it has been seen that weld zone, HAZ and parent material all have different grain size as well as phase composition. Such change has been due to differential heating during welding. This increase and decrease in hardness has been justified with microstructural changes. Smaller grains have high hardness. Higher the pearlite phase higher is the hardness. There is decrease in hardness and strength in weld zone compared to parent zone and this was justified by lower percentage of carbon in weld zone as well as the microstructure of weld zone.

Analyzing the diffusion weldability of copper and porcelain

Abstract Diffusion welding is one of the exclusive welding methods that provides a perfect material interface after joining of different materials and results in high mechanical properties at high temperatures. In particular, this technique can be used for joining porcelain and metal that have distinctly different features. In this study, diffusion welding of copper to porcelain has been investigated. After the diffusion welding with different parameters, shear tests have been applied to the samples in order to investigate the weld properties and the changes in hardness in the weld region. In order to elucidate the changes in microstructure and composition in the weld region, SEM, EDX and XRD analyses were performed on the samples. As a result, the joining of copper and porcelain materials can successfully be performed by diffusion welding. Samples have the highest weld strength, if they are joined by diffusion welding at 900 °C for 60 min and at 4.5 MPa.

Mechanical and microstructural investigations of tungsten and doped tungsten materials produced via powder injection molding

The physical properties of tungsten such as the high melting point of 3420°C, the high strength and thermal conductivity, the low thermal expansion and low erosion rate make this material attractive as a plasma facing material. However, the manufacturing of such tungsten parts by mechanical machining such as milling and turning is extremely costly and time intensive because this material is very hard and brittle.Powder Injection Molding (PIM) as special process allows the mass production of components, the joining of different materials without brazing and the creation of composite and prototype materials, and is an ideal tool for scientific investigations.This contribution describes the characterization and analyses of prototype materials produced via PIM. The investigation of the pure tungsten and oxide or carbide doped tungsten materials comprises the microstructure examination, element allocation, texture analyses, and mechanical testing via four-point bend (4-PB). Furthermore, the different materials were characterized by high heat flux (HHF) tests applying transient thermal loads at different base temperatures to address thermal shock and thermal fatigue performance. Additionally, HHF investigations provide information about the thermo-mechanical behavior to extreme steady state thermal loading and measurements of the thermal conductivity as well as oxidation tests were done.Post mortem analyses are performed quantifying and qualifying the occurring damage with respect to reference tungsten grades by metallographic and microscopical means.

Joining of Dissimilar alloy Sheets (Al 6063&AISI 304) during Resistance Spot Welding Process: A Feasibility Study for Automotive industry

Present design trends in automotive manufacture have shifted emphasis to alternative lightweight materials in order to achieve higher fuel efficiency and to bring down vehicle emission. Although some other joining techniques are more and more being used, spot welding still remains the primary joining method in automobile manufacturing so far. Spot welds for automotive applications should have a sufficiently large diameter, so that nugget pullout mode is the dominant failure mode. Interfacial mode is unacceptable due to its low load carrying and energy absorption capability. Strength tests with different static loading were performed in, to reveal the failure mechanisms for the lap-shear geometry and the cross-tension geometry. Based on the literature survey performed, venture into this work was amply motivated by the fact that a little research work has been conducted to joining of dissimilar materials like non ferrous to ferrous. Most of the research works concentrated on joining of different materials like steel to steel or aluminium alloy to aluminium alloy by resistance spot welding. In this work, an experimental study on the resistance spot weldability of aluminium alloy (Al 6063) and austenitic stainless steel (AISI304) sheets, which are lap joined by using a pedestal type resistance spot welding machine. Welding was conducted using a 45-deg truncated cone copper electrode with 10-mm face diameter. The weld nugget diameter, force estimation under lap shear test and T – peel test were investigated using digital type tensometer attached with capacitive displacement transducer (Mikrotech, Bangalore, Model: METM2000ER1). The results shows that joining of Al 6063 and AISI 304 thin sheets by RSW method are feasible for automotive structural joints where the loads are below 1000N act on them, it is observed that by increasing the spots per unit length, then the joint with standing strength to oppose failure is also increased linearly incase of interfacial failure mode and non linear for pullout failure mode.

Failure criterion for adhesively bonded joints using Arcan´s experimental method

Characterization of polymeric materials mechanical behavior requires some previous knowledge about their structure, which allows the choice of more appropriated models and methods. Polymeric materials, below their glass transition temperature (Tg), may be handled as perfect elastic solids, allowing the use of classic mechanics to characterize their behavior. Polymers above their Tg present a viscous contribution to mechanical behavior, which has to be taken into consideration by modeling it. Adhesively bonded joint, joining of different materials using a polymer as adhesive, adds to the mentioned requirements more parameters, such as surface roughness, adhesive thickness and different types of contributions to adhesively bonded joint strength. This work has the purpose of presenting a mechanical behavior characterization of adhesive bonded joints, concerning their average stress at rupture. A modified Arcan´s device was used to obtain the average stress at rupture under different angles or loading conditions, such as pure shear 0°, pure tensile strength 90° and combined conditions. The experimental results were applied to a theoretical model, which takes into consideration the hydrostatic contribution to the mechanical behavior, called Drucker-Prager Model, which was initially developed to characterize soils.

1602 A1/ポリプロピレン樹脂異材接合における金属表面状態の影響(機械材料・材料加工IV)

1602 A1/ポリプロピレン樹脂異材接合における金属表面状態の影響(機械材料・材料加工IV)

Enlargement of the application range of solid punch riveting by two-piece dies

Punch riveting with solid rivets is an admitted technology in joining by forming of metallic workpieces. Conventional this technology works with a rigid die. This causes the disadvantage of dimensioning the width of the coining contour separately for every single joining task to avoid a prematurely coining during the blanking stage. By using a two-piece die an improvement is feasible. Thus there can be realized a plane surface of coining ring and die ring during the stamping process. So an equal coining ring can be used for all joining tasks. The article shows the advantages of the two-piece dies especially in joining of different materials with distinct differences in strength. The use of these dies effects convenient technological conditions and an extended range of application for solid punch riveting.