Friction Welding Process Research Articles

Process optimization of rotary friction welding of Ti-6Al-4V alloy rods

This paper presents an investigation on the performance of rotary friction welded 25.4 mm diameter Ti-6Al-4V alloy rods. The process parameters used are friction and forging pressure, rotational speed, forging time and upset distance. The heating time was determined by the amount of friction pressure and rotational speed utilised. Visual examination of preliminary weld joints was done which revealed lack of bonding, weld oxidation and discolouration. The final weld joints were examined for mechanical properties. The results revealed that friction welding process parameters have significant influence on the weld joint properties and weld joint integrity. The hardness and ultimate tensile properties of the weld joints varied with the variation in rotational speed and axial pressure. The tensile properties of the weld joints were higher than the parent material at lower rotational speed or higher axial pressure. The weld width was proportional to relative motion and inversely proportional to axial pressure.

The corona bond response to normal stress distribution during the process of rotary friction welding

Continuous drive rotary friction welding was conducted on SUS304 stainless steel rods in diameter of ϕ25 mm under different welding pressures, rotation speeds, and friction time. At the friction interface, the normal stress distributions were measured, and the corona bond (i.e., plasticized metal) was characterized. The results show that, under a constant welding pressure, the normal stress initiates at the periphery of the sample interface, leaving the inner area that seems un-contacted at the very beginning of the friction process. Thereafter, the normal stress extends inside along the radial direction, which leads to its distribution presenting like a “U” shape. The normal stress at the periphery increases much faster than it at the inner area, resulting in the distribution presenting like a “V” shape. Then, the stress in the center continuously increases and the distribution gradually changes into “M” shape. The stress is lastly homogenously distributed. Evolution of the normal stress distribution determines the evolution of the corona bond. At the same time, evolution of the corona bond reacts on the distribution of normal stress. In addition, similar phenomena have been observed under different welding parameters.

Melt processing for enhancing compatibility of aluminum-reinforced acrylonitrile–butadiene–styrene and polyamide 6 for friction welding applications

Friction welding is one of the established solid-state welding techniques with wide aerospace, automobile and industrial applications. For thermoplastic components, it is extremely difficult to join the dissimilar material [e.g., acrylonitrile butadiene styrene (ABS) to polyamide (PA) 6] with friction welding process. For such joining/welding applications, there is a need of strong material compatibility/processing technique. This study highlights melt flow index (MFI) as one of the rheological/flow properties which can be used as controlling parameter for dissimilar thermoplastic friction welding. The twin screw extrusion and fused deposition modeling as melt processing techniques have been used for processing/fabrication of functional/non-functional surfaces/prototypes. The results of study suggest that ABS with 15% Al metal powder by weight (ABS-15Al) and PA6 with 50% Al metal powder by weight (PA6-50Al) have a similar range of MFI as 11.57 and 11.97 g/10 min, respectively (which confirmed the compatibility for joining of both polymers by friction welding). The results are supported by photo-micrographs and mechanical testing.

The microstructures, mechanical properties, and temperature distributions in nodular cast iron friction-welded joint

The paper focuses on an experimental topic relating to the field of friction welding process of a nodular cast iron. The microstructures, phase transformation, temperature distributions, microhardness, and tensile test are all studied within the framework of the paper in question. Maximum temperature measurements in the axial center and periphery of the analyzed joints were equal to 950 and 840 °C, respectively. Both temperature and increasing temperature gradient at the axial center were higher than those at the periphery. The maximum tensile strength of the examined friction-welded nodular cast iron joints was 53% of that of the parent metal. The welding region was composed of deformed graphite nodules, coarse pearlite, proeutectoid ferrite, and acicular martensite. Highly deformed graphite nodules were distributed along the weld interface due to the material flow in the thermo-mechanically affected zone (TMAZ). In the central zone, graphite displayed a striped configuration and ferrite transformed into a martensite structure. In the peripheral region, graphite surrounded by martensite kept the form of individual granules. Maximum hardness at the interface in the TMAZ and the heat-affected zone reached 603 HV and 345 HV, respectively. The executed microstructure analysis showed that the cracks started occurring mostly at the interface of the deformed graphite nodules and then spread through the grain boundaries of metal matrix. The fracture surface appearance showed a cleavage fracture in the peripheral zone and a little dimple fracture around graphite nodules in the central zone.

Multi-objective Optimization of Friction Welding Process Parameters using Grey Relational Analysis for Joining Aluminium Metal Matrix Composite

Aluminium metal matrix composites has gained importance in recent time because of its improved mechanical and metallurgical properties. The welding of aluminium metal matrix composites using conventional welding process has got many demerits so in order to overcome them a solid state welding process is to be employed. To achieve a good strength weld in the aluminium metal matrix composite bars an efficient and most preferred technique is friction welding. In this work the aluminium metal matrix composite AA7075 + 10 % vol SiC-T6 is selected and friction welded. The combination of friction welding process parameters such as spindle speed, friction pressure, upset pressure and burn-off- length for joining the AA7075 + 10 % vol SiCP-T6 metal matrix composite bars are selected by Taguchi’s design of experiment. The optimum friction welding parameters were determined for achieving improved ultimate tensile strength and the hardness using grey relational analysis. A combined grey relational grade is found from the determined grey relational coefficient of the output responses and the optimum friction welding process parameters were obtained as spindle speed – 1200 rpm, friction pressure – 100 MPa, upset pressure – 250 MPa, Burn-off-Length – 2 mm. Analysis of variance (ANOVA) performed shows that the friction pressure is the most significant friction welding parameter that influences the both the ultimate tensile strength and hardness of friction welded AA7075 + 10 % volSiCP-T6 joints. The fractured surface under microstructure study also revealed good compliance with the grey relational grade result. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.17725

Pengaruh Waktu dan Tekanan Gesek terhadap Kekuatan Tarik Sambungan Paduan Aluminium dan Baja Karbon pada Pengelasan Gesek Continuous Drive

The objective of this research was to investigate the effect of friction time and friction pressure on the tensile strength of the joining of two dissimilar materials, aluminum alloy AA6061 and carbon steel, with continuous drive friction welding process. Variations of friction times of 5 seconds, 7 seconds, 9 seconds, and 11 seconds, at each variation of friction pressures of 24 MPa, 32 MPa, and 40 MPa. Controlled variables in this friction welding process were rotational speed of 1600 rpm, upset pressure of 79 MPa which was applied for 60 seconds and diameter of friction surface of specimens which were 15 mm. The resulting strength of the bonding were than evaluated on the basis of tensile strength. Observations of temperature change during the welding process, the distribution of Vickers hardness values around the bonds area, and micro photographs, were used as support to the analysis. The results showed that the longer friction time was applied, the higher tensile strength of the bonds would be, until it began to decrease after a certain maximum value of the tensile strength had been reached. Increased of the tensile strength of the bonding did not occur linearly due to the variation of friction pressure at 9 seconds and 11 seconds of friction time. At 5 seconds and 7 seconds of friction time, increase of friction pressure caused a linear increase of tensile strength. Higher temperatures in the welding process increased the thickness of brittle layer at the bonds boundary. The increase of the brittle layer thickness causes decrease of the tensile strength of the bonds.

Thermomechanical Modelling of Direct-Drive Friction Welding Applying a Thermal Pseudo Mechanical Model for the Generation of Heat

In the present work a 2D axisymmetric thermomechanical model of the direct-drive friction welding process is developed, taking the temperature dependent shear yield stress into account in the description of the heat generation, utilizing a recent thermal pseudo mechanical model originally developed for the friction stir welding (FSW) process. The model is implemented in ABAQUS/Explicit via a subroutine. The application in this case is joining of austenitic stainless steel rods with an outer diameter of 112 mm, used for manufacturing of exhaust gas valves for large two stroke marine engines. The material properties in terms of the temperature dependent flow stress curves used both in the thermal and the mechanical constitutive description are extracted from compression tests performed between 20 °C and 1200°C on a Gleeble 1500 thermomechanical simulator. Comparison between measured and simulated transient temperatures shows relatively good agreement and furthermore, the simulated deformations in terms of upsetting length and flash formation are also in good agreement with the observations from the experiment.

The corrosion behavior of fully deformed zone of friction welded low chromium plain carbon steel joints in optimized condition

The research article deals with the corrosion behaviors of friction welded AISI 52100 grade high carbon and low chromium steel joints. In recent decade, plain carbon steels are replaced with AISI 52100 grade steel in automotive and aerospace sectors to overcome the corrosion defects. In general, the corrosion attacks are more susceptible in joints . Therefore, in this research work, the corrosion behavior of joints was analyzed in its interface and also the relationship between continuous drive friction welding parameters and properties of weld zone are established. The joints were prepared by varying the friction welding process parameters to optimize the required number of experiments. To predict the optimum properties of fully deformed zone, the empirical relationships were developed. The grain size was measured at various zones and the corresponding properties of the joints were analyzed by using scanning electron microscope, optical microscopy, and EDAX.

Hot deformation behavior and constitutive model of GH4169 superalloy for linear friction welding process

In order to realize a better description about the plastic flow behavior in linear friction welding process of GH4169 superalloy, especially at the friction interface where rather elevated temperature and severe deformation happened, it is necessary to adopt an accurate constitutive model of GH4169 superalloy suitable for the high temperature range. The isothermal hot compression tests of GH4169 superalloy at different deformation temperatures and strain rates were designed and conducted using Gleeble-3500 thermo-simulation machine. Based on the measured flow stress-strain data, three constitutive equations were derived on the basis of the modified Field-Backofen (F-B) model, Johnson-Cook (J-C) model and strain compensated Arrhenius model, respectively. The experimental results show that the plastic flow stresses of GH4169 superalloy are significantly affected by the strain rate and temperature. The comparisons of plastic flow stress between the experimental and the calculated results based on three constitutive models show that there are great errors in the calculation on the plastic flow stress at high strain rates by using the modified F-B model and the J-C model, while the strain compensated Arrhenius model can describe exactly the plastic flow stress evolution because the coupled influences of temperature, strain and strain rate are considered. Furthermore, linear friction welding (LFW) experiment and corresponding finite element simulation based on the established constitutive equations were carried out. The comparisons of flash shape and its dimension between the simulated and experimental results indicate that the strain compensated Arrhenius model is more suitable for the LFW numerical simulation of GH4169 superalloy.

Friction push plug welding in airframe structures using Ti-6Al-4V plug

Friction push plug welding, a recent variation of friction welding process has tremendous applications in joining and repairing operations in aerospace and automotive engineering. The main objective of the present work demonstrates joining feasibility of high performance Ti-6Al-4V to low density AA2024 employed in passenger seat track, vertical stabilizers and wing spars of aircraft structures of aerospace applications. Mechanical testing is carried out to analyse the joint integrity and strength of Ti-6Al-4V/AA2024 joints. The microstructural aspects are investigated to study the bonding mechanism to obtain defect-free welds. SEM micrograph reveals the formation of different zones with significant reduction in grain size. EDX analysis confirms the formation of Ti3Al intermetallic compound which is less brittle. Appreciable impact strength of about 286.354 kJ/m2 indicates friction push plug welding as a promising candidate for joining of Ti-6Al-4V and AA2024 in airframe structures.

Rotary friction welding of molybdenum components

Joining of TZM components by inertia rotary friction (IFW) welding is an established industrial process for welding cross-sections up to 1500 mm2. Up-scaling to medium-size components up to 5000 mm2 in a direct drive friction welding process requires a better understanding of the influencing factors of the weld procedure, e.g. machine parameters, weld preforms, and the clamping system. Based on the existing IFW process for TZM tubes, welding parameters were transferred to tubular components of pure molybdenum (OD: 150 mm, ID: 130 mm, 4400 mm2). Successful welds were produced showing a fine-grained, defect-free microstructure. However, molybdenum proved to be more challenging than TZM. Particularly high upset rates and motor overload occurred during the friction phase. Therefore, a study was carried out to reveal the underlying mechanisms with small-size samples under laboratory conditions. It was shown that extensive plastic deformation of the entire weld zone occurred due to higher thermal diffusivity and lower strength of molybdenum compared to TZM. This high upset rate reduces the process window for a reproducible welding procedure significantly. In conclusion, a concentrated energy input during the transition from friction to forge phase is required to countervail the high thermal diffusivity of molybdenum. Based on these observations, the feasibility of friction welding of medium-size molybdenum tubes will be discussed.

Friction Stir Welding of Dissimilar Metal: A Review

Friction Stir Welding (FSW) is a solid-state welding process which produces welds due to the compressive force contact of work pieces which are either rotating or moving relative to each other. The heat required to join different specimens is generated by heating due to friction at the interface. Application of Friction Stir Welding in aerospace industries is very broad. Rolls-Royce now uses friction welding processes for its modern Trent aero engines that drive the Airbus A380 and the Boeing 787. In this paper, Friction Stir Welding of various dissimilar metals is reviewed. The microstructure, hardness, and flow characteristics are also reviewed.

Friction Stir Welding of Dissimilar Metal: A Review

Friction Stir Welding (FSW) is a solid-state welding process which produces welds due to the compressive force contact of work pieces which are either rotating or moving relative to each other. The heat required to join different specimens is generated by heating due to friction at the interface. Application of Friction Stir Welding in aerospace industries is very broad. Rolls-Royce now uses friction welding processes for its modern Trent aero engines that drive the Airbus A380 and the Boeing 787. In this paper, Friction Stir Welding of various dissimilar metals is reviewed. The microstructure, hardness, and flow characteristics are also reviewed.

An Examination of Seamless Ferritic tube and Austenitic alloy tube plate joining by Friction Welding process

In this particular study, Friction welding process is carried out by joining two different alloying materials using an independent tool made up of tungsten to upgrade and certify metallurgical composition. Taguchi L9 orthogonal array and Analysis of Variance (ANOVA) are the optimization techniques used to confirm the capital joint strength characteristics. Optimal peer joint strength characteristics which concludes the optimal joint strength whereas rotational of tool spindle, tube preparation with extrusion and depth impression are the input parameters. Followed by the microstructural investigation by measuring grain size at the welding area. Moreover, the investigation is carried by interference fit condition that accumulates heat from the tool pin and dissipates. Here, with and without backing block activities were carried out to exhibit excellent welding strength at the research end detected as 2355.30 MPa and 2313.03 MPa respectively.

An investigation of Boiler Grade Tube and Tube Plate without block by using friction welding process

FWTPET investigation was carried out to intensify mechanical properties by using the tungsten carbide alloy external tool. In this research probe, those mechanical and metallurgical resources enhancement was depleted by joining boiler grade materials chosen are SA 213 grade tube and SA 387 as tube plate. Even though there were certain research aspects acknowledged, this article was under the investigation of metal bonding technique at without supporting block conditions. Next step of research was being analyzed by Taguchi Optimization technique to diagnose most convincing parameter. Associated procedures of analysis of variance (ANOVA) used to analyses the variation among the groups of the convincing parameter. Output specification was considered as a superlative compressive strength which explores welding ability. The investigation was about by comparing clearance and interference fit method using without supporting block samples. The clearance and interference fit method superior strength exhibits in this FWTPET research space disclosed as 2256.32 MPa and 2275.75 MPa respectively.

Effect of friction welding conditions on tensile strength and hardness of AISI 310 stainless steel joints

This study aims to determine the effect of rotational speed and forging time on tensile strength and hardness through the friction welding process of stainless steel AISI 310. The research was carried out by friction welding process by using the lathe machine with varying rotational speed (550, 1020 and 1800 rpm), forging time (25, 35, 45 seconds), and welding temperature of 1050°C ± 10°. Axial pressure was obtained through the addition of a hydraulic system to the release head of a lathe machine with a forging pressure of 123.8 N/mm2. Furthermore, the friction welding results were tested mechanically by conducting the tensile and hardness tests. The experimental results showed that the highest tensile strength of the friction welding result of 706,61 N/mm2 was obtained at 1800 rpm and 45 seconds, and this value is lower when compared with raw material (780,25 N/mm2). The highest hardness value (61.5 HRC-A) was located on the welded joint section with 550 rpm of rotational speed and 25 seconds of forging time. The hardness of the parent metal is 69.45 HRC-A. The rotational variation influences the hardness value, the higher the rotational speed will increase the hardness. The longer of forging time will decrease the hardness.

Analysis of Mechanical, Metallurgical and Fatigue Behavior of Friction Welded AA6061-AA2024 Dissimilar Aluminum Alloys in Optimized Condition

Dissimilar joints are having greater demands in each and every sectors for reducing the weight of the components with excellent mechanical properties at high temperature and also it possess increased corrosive resistance. Aluminum alloys are widely used in day-to-day applications in which 6xxx series Al alloys are majorly incorporated in automotive industries. The 2xxx series Al alloys offers an increased performance both in static and dynamic conditions due to the presence of copper, chromium, magnesium and iron constituents. In general, 6xxx series alloys undergoes failure with any slight changes in environmental conditions but the 2xxx series Al alloys are having better resistance comparitively. Therefore, in this research work, an attempt was made in order to replace some of the 6xxx series alloys to 2xxx series Al alloys with the help of Friction Welding (FW) process which will enhance the performance of the components. So for, the process parameters were optimized using Response Surface Methodology (RSM) and its effect on the mechanical, metallurgical and fatigue properties were analyzed. Also, the properties of the joints were characterized with the help of advanced facilities such as optical metallurgical microscopy and scanning electron microscopy to understand its surface morphology.

Microstructures and Mechanical Properties of Al/Fe and Cu/Fe Joints by Continuous Drive Friction Welding

The dissimilar pure metals Al/Fe and Cu/Fe with different metallurgical compatibility were joined by continuous drive friction welding. The friction weldability was investigated. The microstructure of the joining interface was analyzed by scanning electron microscopy, and the chemical compositions were tested by energy‐dispersive spectroscopy. The joining strength was evaluated by tensile test, and the fracture was detected by X‐ray diffraction analysis. The results show that sound joints of Al/Fe and Cu/Fe can be obtained by continuous drive friction welding process. A discontinuous reaction layer was formed on Al/Fe interface, and no obvious reaction layer appeared on Cu/Fe interface. The tensile strength of the joints increased with increasing friction pressure, and the highest strength could reach up to 70 MPa for Al/Fe joint and 222 MPa for Cu/Fe joint. All the Al/Fe friction‐welded samples failed at the friction interface, while the Cu/Fe joint under 36 and 44 MPa friction pressure failed at Cu matrix during the tensile test.

Linear friction welding process simulation of Ti-6Al-4V alloy: a heat transfer analysis of the conditioning phase

Linear Friction Welding is an emerging solid-state joining process used for complex geometries. The process is composed of four distinct phases: conditioning (also called initial), transition, friction, and forging. This paper proposes a new numerical approach to simulate the initial phase (phase 1) while reducing the computational time. An implicit fully coupled thermomechanical 2D analysis scheme in ABAQUS was employed to compare the proposed thermal model and the conventional oscillation model. Physical and mechanical temperature-dependent properties of Ti-6Al-4V were implemented in the two models. An excellent agreement was obtained with the experimental temperature profiles published in the literature. The new thermal model reduces the computational time significantly, up to 99% with respect to an oscillating model.

Adaption of a Carreau fluid law formulation for residual stress determination in rotary friction welds

For the numerical simulation of the rotary friction welding process in prior works a modified Carreau fluid law has been successfully adopted, which can so far not be used for the residual stress prediction due to the basic assumptions in this model. Therefore, an extension is proposed accounting for elastic effects, thermal induced stresses and hardening of steels using the data of continuous cooling transformation (CCT) phase diagrams. For the validation of the model, measurements from literature as well as own measurements utilizing partial cut-outs are used. The numerical results correlate well with experimental data for first order residual stresses.