Welding Of Dissimilar Materials Research Articles

Micro-welding of High Thermal Conductive Material Aluminum-Graphite Composite by Pulsed Nd:YAG Laser

The development of advanced materials with superior high thermal properties and high specific strength has led to new metal matrix composites (MMCs) as a great attractive material in electrical and electronic industries. In order to manufacture more practical component from MMCs, a tech-nique for joining MMCs to other similar composites or monolithic materials is strongly required. Therefore, the reliable and economic joining technique is investigated to increase the applications of MMCs. In this study, the overlap welding of pure aluminum and super thermal conductive (STC) aluminum-graphite composite was experimentally and numerically investigated by using a pulsed Nd:YAG laser. In order to discuss the welding of dissimilar materials with different thermophysical properties, the temporal change of heat input was controlled by arranging the laser pulse waveform. The porosities and bumps were observed as the remarkable weld defects in the welding process without a pulse control. On the other hand, the weld bead was largely free of defects, and a size of bump was relatively small with the appropriate controlled pulse waveform. It was clarified that the laser welded joint of an aluminum and a STC aluminum-graphite composite could be successfully achieved with the better weld penetration stability by the appropriate controlled pulse waveform.

Evaluation of PMMA joining to stainless steel 304 using pulsed Nd:YAG laser

This paper reports an experimental study of welding of dissimilar materials between transparent Polymethylmethacrylate (PMMA) and stainless steel 304 sheets using a pulsed mode Nd:YAG laser. The process was carried out for two cases; laser transmission joining (LTJ) and conduction joining (CJ). The former is achieved when the joint is irradiated from the polymer side and the latter when the joint is irradiated from the opposite side (metal side). The light and process parameters represented by the peak power (Pp), pulse duration (τ), pulse repetition rate (PRR), scanning speed (ν) and pulse shape have a significant effect on the joint strength (Fb), joint bead width (b), joint quality and appearance. The optimum parameters were determined according to joint quality, joint strength and bead width. The optimum results for the joint strength and bead width for both LTJ and CJ are 925N, 7.25mm and 495N, 8mm respectively using a rectangular pulse shape (RC). Further modeling studies were carried out based on two methods; one factor at a time method (OFM) and surface response methodology (RSM) method. RSM was used to determine optimum parameters for the experimental data building mathematical models for correlating parameters and responses (Fb and b) as well as to investigate how different parameters interact with each other and their effect on the weld quality.

Strength and microstructure of laser fusion-welded Ti–SS dissimilar material pair

The ability to efficiently create robust and reliable dissimilar metal joints has the potential to enable new functionalities and reduce the manufacturing costs of medical devices. The need for dissimilar material welds in the medical device industry is driven by the unique properties exhibited by biocompatible materials such as stainless steel and titanium, as well as shape memory materials such as NiTi. Many material pairs, however, suffer from significant intermetallic phase formation during welding which greatly reduces their strength. This study investigates the microstructures and strength of the laser fusion-welded titanium–stainless steel dissimilar material pair as a simplified model of the NiTi–stainless steel pair. Compositional and structural analysis of the weld pool is performed and fracture morphologies are analyzed in different regions of the weld joint. The role of weld pool geometry, heat flow, and quench rate on the resultant phases, microstructures, and strength of the welds is discussed.

Statistical test planning for ultrasonic welding of dissimilar materials using the example of aluminum‐carbon fiber reinforced polymers (CFRP) joints

AbstractThis paper is focused on statistical test planning methods to increase process stability by means of reproducibility in comparison to a stepwise empirical variation of each process parameter during solid state joining as well as the significant reduction of experimental time and costs. The methodology will be presented for the specific challenges of ultrasonic welding. This pressure welding technology was investigated systematically for joining aluminum sheet metals to carbon fiber reinforced thermoplastic polymers (CFRP). In this study two aluminum wrought alloys were investigated to be welded onto CFRP with PA66 matrix. To evaluate suitable process parameters, the statistical model named “central composite design circumscribed (CCC)” was used to prove the weldability of the Al/CFRP‐joints. An important advantage of the CCC‐model is the description of the mutual dependence of the three central welding parameters: oscillation amplitude, welding force and energy in relation to the achievable mechanical properties of the joints. It allows the reduction of the number of necessary welds at a factor of seven in comparison to a conventional empirical investigation. All combinations of the welding parameters were proved in tensile shear tests. Additional microstructural analysis helped to understand the mechanical behaviour of ultrasonically welded hybrid joints in detail.

Study on Dissimilar-Material Welding with Vanadium and Austenitic Stainless Steel

The hardness distribution and the effect of post welding heat treatment (PWHT) at 600°C and 1000°C for 1 h and aging heat treatment at 600°C for 1000 h in the dissimilar-material electron beam weld (EBW) joint with pure-V and SUS316L austenitic stainless steel were investigated. The electron beam was positioned just on the butt joint (EB00), shifted by 0.2 mm (EB02) and 0.4 mm (EB04) on the pure-V side. The EBW joint was distinguished into the base metal of V (V-BM), weld metal (WM), interlayer at the edge of the WM of SUS316L side (IL) and base metal of SUS316L (SUS316L-BM). The IL was observed only in the EB02 and EB04 joints. The formation of macro-pore was observed in the EB04 joint. Much higher hardness was observed at the WM and IL of the as-welded EB00 and EB02 joints than the other regions of them. The hardness change in the WM was relatively small due to the PWHT at 600°C up to 1 h, whereas significant increment was observed due to the PWHT at 1000°C for 1 h regardless of the EB position. The hardness of the IL after the PWHT at 600°C was almost twice higher than that of the as-welded one, which showed slightly further increment at 1000°C. Rapid increment of the hardness due to the aging at 600°C for 1–10 h and slightly further increment of it due to the aging for 100–500 h occurred in the WM of the EB00 joint.

Microstructural evolution of aluminum/magnesium lap joints welded using MIG process with zinc foil as an interlayer

Dissimilar material welding between 1 mm-thick magnesium and aluminum alloy plates in lap form was performed using the MIG process with zinc foil as the interlayer material. The zinc foil acted as a barrier layer that restrained reactions between the aluminum and magnesium atoms, and a crack-free lap joint of dissimilar materials was obtained. The interfacial layer between the fusion zone and the unmelted magnesium substrate was mainly composed of Mg–Zn binary intermetallic compounds. The tensile strength of the lap joint was 64 MPa, and a fracture occurred at the interface between the fusion zone and the unmelted magnesium alloy.

Numerical and experiment analysis of residual stress on magnesium alloy and steel butt joint by hybrid laser-TIG welding

Hybrid welding technology has received significant attention in the welding of dissimilar materials recently. While, great welding residual stress and deformation often result by the difference of coefficient of thermal expansion This study describes the thermal elastic–plastic analysis using finite element techniques to analyze the thermo mechanical behavior and evaluate the residual stresses and welding distortion on the AZ31B magnesium alloy and 304L steel butt joint in laser-TIG hybrid welding. A new coupled heat source model was developed which combined by double-elliptic planar distribution, double-ellipsoid body distribution and Rotary–Gauss body distribution model. From the results, it can be concluded that the temperature distribution at the hybrid weld region is exposed to faster rate of heating and cooling in hybrid welding than TIG. Furthermore, compared to the welding stress distribution on the TIG weld, residual stress σy is found about 20% higher on hybrid weld joints, and the residual stress on the 304L steel plate is lower than that on the AZ31B magnesium plate.

Laser Beam Welding with High-Frequency Beam Oscillation: Welding of Dissimilar Materials with Brilliant Fiber Lasers

Brilliant laser beam sources in connection with a high frequent beam oscillation make it now possible to join metallic material combinations, which have been conventionally non-laser weldable up to now. It concerns especially such combinations like Al- Cu, where brittle intermetallic phases occur. Extreme small weld seam with high aspect ratio leads to very short meld pool life time. These allow an extensive reduction of the heat input. On the other side the melting behavior at metallic mixed joint, seam geometry, meld pool turbulence and solidification behavior can be influenced by a high frequent time-, position- and powercontrolled laser beam oscillation.

Finite element simulation of laser transmission welding of dissimilar materials between polyvinylidene fluoride and titanium

Now-a-days, metal to plastic micro-welding is of great interest in the field of biomedical and electronics applications. Laser transmission welding (LTW) has emerged as the most suitable technique for such applications. In this paper, a three-dimensional finite element (FE) thermal model is developed to simulate the laser transmission welding process for joining polyvinylidene fluoride to titanium using a distributed moving heat flux. The objectives of this study are to predict the transient temperature field as well as the weld dimensions. All the major physical phenomena associated with the LTW process, such as, heat radiation, thermal conduction and convection heat losses are taken into account in the model development. The simulation algorithm is programmed as a macro routine within the ANSYS® finite element code. The developed model derives its main advantage from its applicability in parametric studies of a wide range of laser transmission metal to plastic welding problems of different geometrical, material and joint type, requiring only the basic thermo-physical material properties, the geometric details and the laser process parameters as input. Keywords: Laser transmission welding, Temperature field, Weld dimension, Finite element analysis, Thermal modeling

Welding of dissimilar materials

In fossil fuel fired power plants, appropriate materials are required which correspond to the different temperature and oxidizing conditions in the boiler and in the super-heater sections. Pipe steels with (T/P22; T/P23; T/P24) must be welded with 9–12%Cr steels (T/P91; T/P92). In this area, the choice of the appropriate welding filler material is decisive for the quality of the connection. This report highlights the possibilities for achieving optimal qualities in different dissimilar metal welds under conditions of reduced carbon diffusion.

Deformation behaviour of spot-welded high strength steels for automotive applications

Numerical simulation of component and assembly behaviour under different loading conditions is a main tool for safety design in automobile body shell mass production. Knowledge of local material behaviour is fundamental to such simulation tests. As a contribution to the verification of simulation results, the local deformation properties of spot-welded similar and dissimilar material joints in shear tension tests were investigated in this study for a TRIP steel (HCT690T) and a micro-alloyed steel (HX340LAD). For this reason, the local strain distribution was calculated by the digital image correlation technique (DIC). On the basis of the hardness values and microstructure of the spot welds, the differences in local strain between the selected material combinations are discussed. Additionally, the retained austenite content in the TRIP steel was analysed to explain the local strain values. Results obtained in this study regarding similar material welds suggest significant lower local strain values of the TRIP steel HCT690T compared to HX340LAD. One reason could be the decrease of retained austenite in the welded area. Furthermore, it has been ascertained that the local strain in dissimilar material welds decreases for each component compared with the corresponding similar material weld.

Fibre laser welding of dissimilar alloys of Ti-6Al-4V and Inconel 718 for aerospace applications

Challenges in dissimilar materials welding are the differences of physical and chemical properties between welding materials and the formation of intermetallic brittle phases resulting in the degradation of mechanical properties of welds. However, dissimilar materials welding is increasingly demanded from the industry as it can effectively reduce material costs and improve the design. In aerospace applications, Ti-6Al-4V titanium alloy and Inconel 718 nickel alloy have been widely used because of their superior corrosion resistance and mechanical properties. In this study, a single-mode continuous-wave fibre laser was used in butt welding of Ti-6Al-4V to Inconel 718. Investigations including metallurgical and mechanical examinations were carried out by means of varying processing parameters, such as laser power, welding speed and the laser beam offset position from the interface of the metals. Simple analytical modelling analysis was undertaken to explain the phenomena that occurred in this process. Results showed that the formation of intermetallic brittle phases and welding defects could be effectively restricted at welding conditions produced by the combination of higher laser power, higher welding speed and shifting the laser beam from the interface to the Inconel 718 alloy side. The amount of heat input and position of laser beam to improve the Ti-6Al-4V/Inconel 718 weld quality are suggested.

Experimental Investigations on Friction Welding of AL 6061 and SS 304

The friction welding of dissimilar materials is more complicated than welding similar materials due to differences in the physical, thermal, chemical and mechanical properties of base materials. The welding of Al 6061 and SS 304 is susceptible to intermetallic layer formation. The interface properties are degraded due to formation of intermetallic layer at the weld interface. The formation of intermetallic compounds strongly depends on local temperature attained during the welding process. These intermetallic compounds are responsible for brittle failure of the components. In the present study experimental investigations are done on influence of joint geometry on the interface properties of Al 6061 and SS 304 friction welded parts. A new joint geometry is designed for friction welding to enhance the quality of weld joint. The shape of new joint geometry removes the oxides and other unwanted impurities from the joint interface due to formation of burrs during friction phase of welding process. The advantages of the new joint geometry, when compared to regular joint geometry, are many, which include a) reduction in material consumption, b) reduction is energy consumption, c) use of machine with lower capacity, d) reduction in the formation of intermetallics, e) reduction in the size of the heat affected zone (HAZ) and f) improved mechanical strength.

Interfacial Behavior of Dissimilar Friction Welded Nodular Cast Irons with Low Carbon Steels

Welding of dissimilar materials is frequently accompanied by structural and technological difficulties and not always successful. The knowledge resulting from dissimilar welding experiments can be used to further identify directions and suitable technological parameters for optimal results. This paper report on the difficulties encountered on friction welding of nodular cast irons with low alloyed steels, due in principle to the low deformation capacity and the microstructural differences. It was shown through experiments that low friction times and high axial pressure leads to a significant plastifiation of the cast iron, while the low alloyed steel remains practically undeformed. The early (premature) plastifiation of the cast iron leads to a radial expulsion of the base structure associated with a continuous transport of the graphite nodules in the joint plan. As a result, a new graphite film forms which hinders a metallic contact between the parts and a welded joint. Qualitative and quantitative electron microscopy observations reveal carbon and alloying elements diffusion phenomena on the interface of the dissimilar materials to be joined.

Welding of dissimilar materials

In fossil fuel fired power plants, appropriate materials are required which correspond to the different temperature and oxidizing conditions in the boiler and in the super-heater sections. Pipe steels with (T/P22; T/P23; T/P24) must be welded with 9–12%Cr steels (T/P91; T/P92). In this area, the choice of the appropriate welding filler material is decisive for the quality of the connection. This report highlights the possibilities for achieving optimal qualities in different dissimilar metal welds under conditions of reduced carbon diffusion.

809 Laser spot welding of dissimilar materials between PET and metals

PET/Cu and PET/SUS304 is able to joint using Nd:YAG spot laser welding. The weld area and joining strength for the PET/SUS304 joint is higher than that for PET/Cu joint. Formation of bubbles in PET and molten pool at the metal can be observed significantly in the case of PET/SUS304 joint and this due to higher absorption of laser beam compared with copper.

Joining of stainless steel and copper materials with friction welding

PurposeThe purpose of this paper is to investigate mechanical and metallurgical variations at interfaces of commercial austenitic‐stainless steel and copper materials welded by friction welding.Design/methodology/approachIn this paper, austenitic‐stainless commercial steel and copper materials are welded using the friction welding method. The optimum parameters are obtained for the joints. The joints are applied to the tensile and micro‐hardness tests. Then, micro‐ and macro‐photos of the joints are examined.FindingsIt is found that some of the welds show poor strength depending on some accumulation of alloying elements at the interface result of temperature rise and the existence of intermetallic layers.Research limitations/implicationsIt would be interesting to search about the toughness values and fatigue behaviour of the joints. It could be a good idea for future work to concentrate on the friction welding of these materials.Practical implicationsFriction welding can be achieved at high‐production rates and therefore is economical in operation. In applications where friction welding has replaced other joining processes, the production rate has been increased substantially.Originality/valueThe main value of this paper is to contribute to the literature on friction welding of dissimilar materials.

Resistance Spot Welding of Dissimilar Materials of Austenitic Stainless Steels and IF (Interstitial Free) Steels

The spot weldability of dissimilar metal joints between stainless steels (AISI316) and interstitial free (IF) steels were investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensileshear strength, hardness, and microstructure. The fracture surface was investigated by using a Scanning Electron Microscopy (SEM). The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the STS316 sheet was larger due to the higher bulk-resistance. The microstructure of the fusion zone was fully martensite. In order to evaluate the microstructure further, dilution of stainless steels were calculated and imposed onto the Schaeffler diagram. The predicted microstructure from the Schaeffler diagram was martensite. In order to confirm the predicted microstructure, XRD measurements were carried out. The results showed that that initial weld nugget was composed of austenite and martensite.

Solidificação da zona de fusão na soldagem do AISI 304 com inconel 600 por laser de Nd: YAG

Neste trabalho estudou-se a morfologia de solidificação da zona de fusão, numa junta formada a partir de materiais dissimilares, composta por aço inoxidável austenítico AISI 304 e por liga de níquel Inconel 600, soldada com laser pulsado de Nd:YAG. Os parâmetros do feixe laser e do sistema óptico foram selecionados, visando obter uma solda com penetração total e bom acabamento superficial. A caracterização microestrutural foi realizada por microscopia ótica, onde se observou uma zona de fusão com penetração total do tipo keyhole, a presença de pequenos poros e a ausência de trincas. As juntas soldadas foram caracterizadas também, por meio de microscopia eletrônica de varredura (MEV). Medidas realizadas por espectrometria de raios X por dispersão de energia na zona de fusão indicaram uma distribuição levemente heterogênea de níquel e ferro. Observou-se que o início de solidificação da zona de fusão ocorreu por meio de crescimento epitaxial. A morfologia de solidificação da ZF foi basicamente dendrítica e celular sendo, influenciada pelo gradiente de temperatura, velocidade de solidificação e composição química. As variações de composição química e da morfologia de solidificação não alteraram significativamente os valores de microdureza Vickers na zona de fusão. Resultados obtidos nos ensaios de tração indicaram valores de eficiência de soldagem adequados.

Dissimilar material welding of rapidly solidified foil and stainless steel plate using underwater explosive welding technique

Rapidly solidified amorphous and metallic glass thin foils clad on a stainless steel base plate is attempted by employing underwater shock wave assembly. The conditions of the explosive welding are numerically analyzed and discussed based on the earlier welding limits. The thin foils successfully welded along the length of 50 mm show clear waves typically found in explosively welded interface. The interfacial microstructure characterized through optical and scanning electron microscopes shows evidence of excessive melting generated due to the trapping of metal jet in limited area.