Dissimilar Material Combinations Research Articles

Parametric investigation of friction stir welding of aluminum alloy and Inconel 718 using finite element analysis

Friction Stir Welding (FSW) has emerged as a prominent technique for joining metallic materials, offering advantages in both similar and dissimilar material combinations. Despite its effectiveness, further advancements are needed to address industry demands and enhance the understanding of the FSW process. Welding nickel-based superalloys like Inconel 718 poses specific challenges, with existing literature suggesting that achieving successful welds requires high axial forces and precise process parameters, limiting its practical application in industries. To tackle these issues, this research proposes the utilization of 3D finite element models integrating multiphysics aspects, encompassing material flow and heat transfer mechanisms such as conduction, convection, and radiation. These models were validated against existing experimental data and employed to analyze temperature and strain distributions within the heat affected zone and weld nugget. The findings offer insights into the impact of various process parameters, including rotational speed, welding speed, normal force, cooling rate, and the effect of induction preheating, on key performance metrics like temperature profiles, grain size distribution, microhardness, and stress evolution. The outcomes underscore a notable correlation between process variables and performance indicators, facilitating a comprehensive understanding of the FSW process dynamics.

Experimental investigation on solidification cracking & intergranular corrosion of AISI 321 & AISI 316 L dissimilar weld on pulsed current gas tungsten arc welding (PCGTAW)

Dissimilar metal combinations are frequently employed in the power generation and nuclear industries. Where stainless steel piping systems are connected to pressure vessels made of low-alloy steel, the subsystems of liquid rocket engines also have different, dissimilar material combinations. Dissimilar welding plays a vital role in ensuring the integrity, performance, and reliability of components and structures operating in cryogenic environments, in this study, plates of AISI 316L and AISI 321, each 5 mm thick, were successfully joined using the pulsed current gas tungsten arc welding (PCGTAW) technique with optimized process parameters. These weld joints are mostly present in rocket engines subjected to a cryogenic environment. Due to the low temperature environment, the metallurgical properties of these joints change, which affects their mechanical properties. As it is a structural part, PCGTAW welding is most common method for joining this kind of material.In this work, Microstructural analysis of the weldment revealed a combination of vermicular, lacy, and acicular ferrite morphologies in the fusion zone at the root, mid, and crown locations.Furthermore, no solidification cracking was detected in the weldments based on the optical micrograph and SEM results. Intergranular corrosion (IGC) testing indicated the absence of a ditch structure, suggesting that the heat-affected zone (HAZ) on both sides of the weld joint was not being susceptible to sensitization. However, the HAZ of the AISI 316L side exhibited coarser grains compared to AISI 321. Analysis of tensile properties revealed a significant influence of the testing environment on the tensile strength of the dissimilar welded joints. At room temperature, the average ultimate tensile strength (UTS) was measured as 621 MPa. Remarkably, at cryogenic conditions, the average tensile properties significantly increased to 1319 MPa.Microhardness analysis showed the highest hardness associated with the AISI 321 side. The fusion zone exhibited a large deviation in the hardness profile (205 ± 10 HV), with the highest average hardness observed in the middle part of the weld. However, the hot cracking behavior of the weld was investigated by using a suutula diagram at various locations of the weld. The investigation revealed that the Creq/Nieq ratio exceeded the critical threshold value, effectively diminishing the propensity for hot cracking in the fusion zone. Overall, these findings underscore the effectiveness of the PCGTAW technique in joining dissimilar materials, as well as the importance of microstructural and mechanical property evaluations, especially under extreme operating conditions such as cryogenic temperatures.Paraphrase.

Friction Stir Welding Benefits Technique over Other Welding Techniques of Dissimilar Metals

Abstract: Due to the low heat input situation, solid state welding (SSW) has demonstrated higher potential for integrating a variety of equivalent and dissimilar material combinations. The temperature stays below the melting point of the source materials throughout the solid-state welding process. Compared to fusion welding, solid state welding offers the highest quality. Aeronautics, nuclear, space, and aviation are just a few of the industrial production sectors that utilize the solid-state welding technology. Diffusion welding, explosion welding, friction welding, forge welding, cold welding, role welding, hot pressure welding, and ultrasonic welding are just a few of the SSW techniques covered in the current article. This study looks at a variety of SSW kinds and solid-state welding applications. This study examines many types of SSW and the applications of solid-state welding. Current Study includes the pros and cons of other welding techniques over friction stir welding.

Friction Stir Welding Benefits Technique over Other Welding Techniques of Dissimilar Metals

Abstract: Due to the low heat input situation, solid state welding (SSW) has demonstrated higher potential for integrating a variety of equivalent and dissimilar material combinations. The temperature stays below the melting point of the source materials throughout the solid-state welding process. Compared to fusion welding, solid state welding offers the highest quality. Aeronautics, nuclear, space, and aviation are just a few of the industrial production sectors that utilize the solid-state welding technology. Diffusion welding, explosion welding, friction welding, forge welding, cold welding, role welding, hot pressure welding, and ultrasonic welding are just a few of the SSW techniques covered in the current article. This study looks at a variety of SSW kinds and solid-state welding applications. This study examines many types of SSW and the applications of solid-state welding. Current Study includes the pros and cons of other welding techniques over friction stir welding

Influence of Metal Surface Structures on Composite Formation during Polymer–Metal Joining Based on Reactive Al/Ni Multilayer Foil

Progressive developments in the field of lightweight construction and engineering demand continuous substitution of metals with suitable polymers. However, the combination of dissimilar materials results in a multitude of challenges based on different chemical and physical material properties. Reactive multilayer systems offer a promising joining method for flexible and low‐distortion joining of dissimilar joining partners with an energy source introduced directly into the joining zone. Within this publication, hybrid lap joints between semicrystalline polyamide 6 and surface‐structured austenitic steel X5CrNi18–10 (EN 1.4301) are joined using reactive Al/Ni multilayer foils of the type Indium–NanoFoil. The main objective is to examine possibilities of influencing crack initiation in the foil plane by variation of joining pressure and different metal surface structures with regard to geometry, density, and orientation. Thus, the position of foil cracks is superimposed onto the metal structure and associated filling with molten plastic is improved. Consequently, characterization of occurring crack positions as a function of joining pressure and metal structure, analysis of the composite in terms of structural filling and joint strength, as well as possible causes of crack initiation are evaluated.

Application of friction surfacing for solid state additive manufacturing of cylindrical shell structures

Solid-state additive manufacturing (AM) via friction stir based processes is gaining increased attention as these techniques are feasible for several similar and dissimilar material combinations and induce significantly lower energy input to the subjacent structure than fusion-based approaches as material melting is avoided. Available research concentrates on linear depositions; however, further development of these techniques towards application necessitates more complex deposition paths, e.g. curves and the crossing of edges of previously deposited layers. In this study, the solid-state layer deposition process of friction surfacing (FS) is investigated in terms of process behavior and appearance of the resulting deposit when curved deposition paths are applied. With advancing side on the curve's inner edge, material build-up occurs predominantly on this side of the layer, which results in a deposit of inhomogeneous thickness. This phenomenon is related to the FS process characteristic due to the superposition of rotational and travel movement on a curvature, and is more pronounced for curves with small radii. A further challenge exists for closed structures, where the deposition has to cross previously deposited layers. This can be successfully achieved by reducing the travel speed prior to passing the edge to provide sufficient plasticized material thickness below the stud tip. Overall, the study provides an understanding of the FS process behavior and process parameters for curved paths. Furthermore, recommendations for process control and path planning, e.g. for building closed cylindrical shell structures, are deduced.

Research on X-ray-based energy conversion technology and assessment of application prospect

A new type of wireless energy transfer (radiation energy to electricity) power system is proposed for small-scale distributed energy utilization. To utilize radiation energy efficiently, energy conversion technologies based on different conversion modules and dissimilar material combination schemes are used. A variety of schemes such as single photovoltaic cell and single/multilayer fluorescent layer integrated with photovoltaic cell are designed. The maximum power density ranges from 7.93 nW/cm3 (tube voltage: 30 kV, tube current: 1 mA) to 6.7 µW/cm3 (tube voltage: 110 kV, tube current: 1 mA). After the structure layout of the system is matched and optimized, the maximum output power in radio-luminescent mode can be much higher than that in radio-voltaic mode. In particular, the maximum output power of conversion modules with a stacked layer can be increased by more than 36 times in radio-luminescent mode compared to radio-voltaic mode. At the same time, the effect of the distance of wireless energy transfer on the output performance of the energy conversion module is analyzed. To adjust the radiation intensity and field parameters better, X-ray tube is used as the radiation excitation source for performance testing and analysis. The performance attenuation of different energy conversion modules is similar when responding to X-ray over long distances. Compared with the radio-voltaic mode, the findings of this paper show that the output power of the system based on the radio-luminescent mode can be an order of magnitude higher.

Hot Cracking Characteristics During Single-Mode Fiber and Green Laser Welding Processes in Lithium-Ion Battery Pack Manufacturing

Solidification cracking during lithium-ion battery packaging was metallurgically investigated, specifically for Cu-steel dissimilar materials. To this end, single-mode fiber and green lasers were employed under heat input conditions ranging from 1.3 to 8.0 J/mm. For both laser welds, solidification cracking was concentrated in the steel region of the fusion zone, particularly in the locally Cu-depleted region, regardless of the welding condition. Modified self-restraint tests were performed for overlapping dissimilar material combinations to elucidate the mechanism of solidification cracking. Analysis of the solidification cracking surface revealed that approximately 15?30 mass% Cu existed on the surface. Cu was highly enriched with a droplet shape, formed during solidification within the miscibility gap. By calculating the non-equilibrium weld mushy zone range based on the diffusion-controlled Scheil’s model, the solidification cracking in the Cu-depleted region was estimated at 453 K. It was strongly affected by the severe segregation of Cu (95.7 mass%) in the residual liquid at the terminal stage of the solidification path. Therefore, from a welding metallurgical perspective, homogeneous Cu distribution and minimization of Cu segregation within the fusion zone are essential for suppressing or minimizing the solidification cracking susceptibility of Cu?steel dissimilar laser welding.

Dissimilar Laser Beam Welding of Titanium to Stainless Steel Using Pure Niobium as Filler Material in Lap Joint Configuration

In the present investigation, commercially pure titanium is welded to AISI 316L stainless steel by intermixing niobium as filler material in a lap joint configuration. For this purpose, a pulsed Nd:YAG laser with various pulse durations and pulse peak powers is employed to obtain different mixing conditions for the materials. It will be demonstrated that, despite the implementation of the filler material, the weld seams are characterized by a high affinity for cracking, which in turn can be attributed to the formation of hard intermetallic compounds. Nevertheless, utilization of optimized process parameters can yield crack-free specimens in a reproducible manner through equable intermixing of otherwise critical alloy elements. Lap-shear forces of up to 140 N can be achieved with a single weld seam measuring 2.5 mm in length. By increasing the joint area with four adjacent weld seams, maximum loads up to 320 N are attained, thus exceeding the yield strength of the applied stainless steel. Considering the biocompatibility of the niobium filler material used, this work provides the foundation for this dissimilar material combination to be implemented in future medical technology applications.

Interface and microstructural characteristics of titanium and 304 stainless steel dissimilar joints by upset butt welding using a gleeble thermo mechanical simulator

This work discusses joining dissimilar material combinations of commercial pure titanium and 304 stainless steel utilizing an upset butt welding process. The process involves rapid heating to a temperature of 1150 °C at a heating rate of 200 °C/s with simultaneous application of pressure at a level of 1.5 MPa to achieve fusion. Then, the joints are post-heated to 850 °C during the soaking period for 90 min to relieve the welding residual stresses and achieve good bond strength. The upset welding experiments are conducted with the help of a Gleeble thermomechanical simulator. This process does not require the conventional severe metallographic preparation generally used for the typical diffusion bonding process. The weld joint achieves an ultimate tensile strength of 274 MPa, approximately 60% of the strength of commercial pure titanium. Moreover, intermetallic compounds occurred at the interfaces, which were attributed to significant changes in the microhardness of the Ti/SS alloy.

Effects of Performance and Normalized Parameters on Various Materials Based Multistage Thermoelectric Generator

Abstract Multi-staging and variable cross section greatly improve the performance of thermoelectric generators. Hence, the present theoretical study analyzes a multi-stage-variable-shaped thermoelectric generator (MVS-TEG) for a combination of dissimilar materials. Effects on voltage, power, conversion efficiency, normalized constraints (voltage, power, and conversion efficiency), and second law efficiency with a row number, exhaust inlet temperature, and the coolant flowrate have been investigated. Results reveal that the row number is the most critical input parameter followed by exhaust inlet temperature and coolant flowrate. Also, the work gives optimum values of rows for voltage and power as Nx = 19 for MVS TEG-1, MVS TEG-3, and MVS TEG-4 while Nx = 18 for MVS TEG-2. The exhaust inlet temperature variation increases the voltage and power output by 54–59% and by 53–58% respectively. The coolant flow variation has a greater impact on the conversion efficiency and the average improvement in the efficiency is about 9.23% in the present study. The second law efficiency decreases with the increase in all the input parameters.

Cross-plane thermal transport in multiplayer graphene/h-BN van der Waals heterostructures: The role of interface morphology

The combination of dissimilar materials to build heterostructures has opened up new possibilities for the use of graphene in a variety of applications. Among these, the stacking of graphene and h-BN into graphene/h-BN (GBN) van der Waals (vdW) heterostructures is particularly promising for use as thermal interface materials and underfill materials in new electronic devices because of their remarkable thermal properties and electrical insulation endowed by h-BN if it encapsulates graphene. The heat dissipation performance of these GBN heterostructures depends heavily on the interfacial thermal conductance (ITC) of graphene and h-BN. Herein we explore the heat transfer across multilayer GBN vdW heterostructures by nonequilibrium molecular dynamics simulations and put emphasis on the interface morphology. The tunable ITC of the heterostructure can be achieved by modifying the interfacial layers through composition diffusion, vacancy density and pattern, hydrogenation, and isotope. The simulation results demonstrate that hydrogenation is the most efficient approach to tailor the ITC with a large variation, followed by the composition diffusion. Composition diffusion can induce a stronger interaction between graphene and h-BN, resulting in a 70% improvement in the ITC of the GBN vdW heterostructure. This study offers valuable perspectives to the physical mechanisms behind the interface morphology-dependent ITC, and can facilitate the design of novel GBN vdW heterostructures for efficient heat dissipation.

Effect of mating material on wear behaviour of Ni-based hardface coating

The selection of tribopairs, including mating materials, plays a crucial role in controlling material loss under rubbing conditions. In a fast breeder nuclear reactor, almost all moving components have been provided with a hardfaced coating at the mating surfaces for their longer life. Though, in most cases, the hardfaced surfaces come into contact with the components having the same coating; in some instances, they are allowed to rub against other materials. In the present investigations, an effort was made to study the wear behaviour of a Ni-based hardfaced coating made on 316LN stainless steel under similar and dissimilar mating conditions. Prior to wear tests, a defect-free hardface coating of Ni-based hardfacing alloy was made on 316LN stainless steel using plasma transferred arc welding process and subsequently characterized for its microstructure and hardness. Wear tests under dry sliding conditions were carried out at ambient temperature. The specific wear rate for dissimilar mating conditions was found to be one order of magnitude higher than the same rate obtained from similar mating conditions. Moreover, adhesive wear was the dominant wear mechanism in both mating conditions. It is clear from the study that similar material combinations should be given preference in the design of tribopairs instead of dissimilar material combinations to avoid significantly higher material losses for materials with lower hardness. The reported results will provide insight for carefully designing the tribopairs for critical applications.

Intelligent Testing and Analysis of Dissimilar Steel Welds for Industrial Throttle Flowmeter

The throttling flowmeter used in utility boilers has been used as a measuring instrument for a long time. However, its safety performance, such as welding, lacks enough attention. The manufacturing welds of the throttling flowmeter are welded with austenitic stainless steel and pearlitic heat-resistant steel. Cracks and other defects are generally found in the inspection and detection of the manufacturing welds of throttling flowmeters in service, which have serious potential accidents. To find out the relationship between weldingdissimilar steels and defects, the microhardness indentation method was used to measure the residual stress of welding. Combined with the self-developed calculation software of microscopic indentation residual stress distribution, we used the difference between the color of the indentation area and the surrounding area to quickly measure the indentation strain collected by the microscope using the computer image recognition algorithm, which greatly improved the accuracy and speed of the microscopic indentation residual stress test. The results show that the residual stress at the weld of dissimilar steel is relatively large, and the mechanical property test is generally unqualified. The microindentation residual stress analysis method based on computer image recognition is used to quickly, intuitively, and accurately reveal the direct relationship between the combination of dissimilar steel welding materials and the generation of cracks and other defects.

Influence of different surface conditions on mechanical properties during ultrasonic welding of aluminum wire strands and copper terminals

Ultrasonic metal welding (USMW) has become considerable attention in terms of its suitable applications compared to conventional fusion welding techniques. The main advantage of USMW results from the comparatively low process times and joining temperatures below the melting point. Thus, USMW is particularly used for the joining of dissimilar material combinations, e.g., aluminum and copper (Al/Cu), in battery cell production or wiring harness applications. However, process fluctuations in USMW of Al/Cu joints can occur due to varying surface conditions of the joining materials. Therefore, this study investigated different surface conditions of copper terminals and their effects on mechanical properties. At first, three different surface conditions were generated, respectively: surface cleaning (sulfuric acid and ethanol), structuring process by laser, and structuring process by milling. These modifications are compared with the terminals in the initial state (contaminated). The characterization of the terminal surfaces was carried out with 3-D laser scanning microscopy as well as light microscopy. The mechanical conditions were examined with shear tensile tests. The tensile tests showed a significant influence of the surface condition on the resulting failure loads compared to the initial state. The highest failure loads could be achieved with the structured terminals (+ 48%), whereas contaminated terminals and terminals with notches exhibited comparatively poor failure loads (− 28%). This can be explained by varying interface formations between the terminal and the wire, which was detected by metallography and SEM analysis. Furthermore, it was figured out that the interface between aluminum and copper exhibits a firm and formed closure bond and hence increased failure loads for laser-structured terminals. Additional investigations by SEM revealed no detectable occurrence of intermetallic phases.

Hybrid Thermoplastic-Metal joining based on Al/Ni multilayer foils – Analysis of the joining zone

Multi material pairings like metal-plastic hybrid compounds are becoming increasingly important across all industrial sectors. However, the substitution of metals by plastics leads to a multitude of challenges based on the combination of dissimilar materials. The variations in the chemical and physical properties of the used materials require innovative joining processes. The application of reactive multilayers represents an advanced joining method for flexible and low-distortion joining of dissimilar joining partners by means of a short-term and localized application of thermal energy. In the context of this publication, the joining process between semi-crystalline polyamide 6 and austenitic stainless steel X5CrNi18–10(EN 1.4301 / AlSI304) based on reactive Al/Ni multilayers is investigated. In addition to evaluation of resulting joint strength, the focus of the work is in particular the characterization of the resulting failure behavior at the fracture interface under tensile load and the deriving binding mechanisms in the joint. From the results obtained, it is estimated that a direct bond can be generated between plastic and metal despite the presence of a residual reacted foil in the joining area. The structures present in the metal surface have a particularly positive influence on crack initiation and the resulting increased bond strength.

Tube Joining by a Sheet Flange Connection

Joining of tubes to tubes by means of plastic deformation at ambient temperature allows one to solve the main limitations produced by the necessity of joining thin-walled tubes of low-to-medium diameter size made from materials that are not suitable to be welded and/or have reduced contact interfaces. The new joining solution allows one to obtain permanent mechanical joints of tubes or pipes by means of an accessory lightweight sheet metal flange subjected to annular indentation and subsequent injection of its material towards the tube walls to produce a mechanical interlock between the different elements. The sheet-flange connection can then be utilized to affix the joined tube assembly to walls or other different structures and equipment, by means of fasteners or other joining accessories attached to the sheet flange. Similar or dissimilar material combinations can be easily and safely produced while guaranteeing levels of leak-tightness within the maximum internal operating pressure of the individual tubes. A combined numerical–experimental approach is employed to identify the operative parameters as well as to explain the deformation conditions. Pull-out loads and internal fluid pressure are applied to the manufactured joint to evaluate its behavior under typical operating conditions that it may be subjected to during its service life depending on the application.

Process optimization and study of the co-sintering behaviour of Cu-Ni multi-material 3D structures fabricated by spark plasma sintering (SPS)

The present work focuses on the possibility of manufacturing multi-material structures by spark plasma sintering (SPS), thereby broadening the field of application of this process by taking full advantage of the specific properties of individual materials. As a combination of dissimilar materials to be co-processed, CuCrZr and nickel are of particular scientific and technological interest. For the processing of complex 3D multi-material geometries made of highly dissimilar materials, the sintering behavior of each individual material should however be as identical as possible. Since both materials have different physical and mechanical properties, the sintering behavior of the two individual powder materials is first characterized at different uniaxial pressures, heating rates and holding times. A strategy to determine optimal sintering conditions for the processing of multi-material structures is then developed, based on representation of the densification data of each material in the form of master sintering curves (MSC) and surfaces (MSS). From the MSS, an optimal uniaxial pressure of 35 MPa was determined and the holding time to achieve dense multi-material structures at a temperature of 1223 K was estimated. Different configurations of CuCrZr-Ni multi-material samples were successfully sintered using these parameters and microscopic analyses showed that the relative density in these parts is >99.8, in both CuCrZr and Ni.

Qualification & testing of joining development for DEMO limiter component

A development plan for validation of functional principles is defined to support the challenges of mock-up manufacturing and testing. It is aimed to develop the process and infrastructure for qualifying fusion components for the limiters in the European DEMO. The limiters are components that define the plasma boundary by direct contact during normal and off normal transient events and thus they protect the First Wall of the Breeding Blanket System from extreme heat fluxes during these events. Within this framework, the joints play an important role for making feasible the combination of dissimilar materials required for the plasma facing components (PFCs) by providing a compliant interlayer. The main limiter PFC functionality is to act as thermal barrier, therefore the materials combination shall be able to support the thermal gradient between the high heat flux (HHF) from the plasma and the heat sink. The primary aim of the PFC is to ensure the structural integrity of the heat sink of the PFC (to prevent in-vessel loss of coolant accident), as it is foreseen that during the off-normal transients the PFC surface may melt or evaporate. Minimizing the large deformation and guaranteeing the strength and fatigue behaviour of the joints is required to achieve this.Therefore, a testing programme for joining development and qualification based on brazing technology is performed. It is focused on joint assessment between representative filler metals (OB1025TM, OB950TM, PB950TM, NBLMTM & H-BronzeTM) from the different families in the market and the chemical compatibility, capillarity flow and spreadability on the typical base materials used for PFC (laser powder bed fusion additive manufactured W-6%Ta, W, P91, OFHC Copper, CuCrZr). The main results show good wetting of the gold-copper alloy (OB1025TM) with all the base materials. It allows to progress with the integration of a PFC to create the process and infrastructure for optimizing the design of critical joints. NBLMTM seems to be an interesting filler for materials with high melting temperature as tungsten and P91 and OB950TM presents acceptable wetting condition with the base materials. PB950TM is rejected because the excess of wetting on all the base materials.

Tailored Forming of hybrid bulk metal components

Multi-material bulk metal components allow for a resource efficient and functionally structured component design, with a load adaptation achieved in certain functional areas by using similar and dissimilar material combinations. One possibility for the production of hybrid bulk metal components is Tailored Forming, in which pre-joined semi-finished products are hot-formed using novel process chains. By means of Tailored Forming, the properties of the joining zone are geometrically and thermomechanically influenced during the forming process. Based on this motivation, forming processes (die forging, impact extrusion) coupled with adapted inductive heating strategies were designed using numerical simulations and successfully realised in the following work in order to produce demonstrator components with serial or coaxial material arrangements. The quality of the joining zone was investigated through metallographic and SEM imaging, tensile tests and life cycle tests. By selecting suitable materials, it was possible to achieve weight savings of 22% for a pinion shaft and up to 40% for a bearing bush in the material combination of steel and aluminium with sufficient strength for the respective application. It was shown that the intermetallic phases formed after friction welding barely grow during the forming process. By adjusting the heat treatment of the aluminium, the growth of the IMP can also be reduced in this process step. Furthermore, for steel-steel components alloy savings of up to 51% with regard to chromium could be achieved when using low-alloy steel as a substitute for high-alloy steel parts in less loaded sections. The welded microstructure of a cladded bearing washer could be transformed into a homogeneous fine-grained microstructure by forming. The lifetime of tailored formed washers nearly reached those of high-alloyed mono-material components.