Rotary Friction Welding Process Research Articles

Rotary friction welded C45 to 16NiCr6 steel rods: statistical optimization coupled to mechanical and microstructure approaches

In the present work, the dissimilar joints between C45 carbon steel and nickel-chromium 16NiCr6 steel rods were produced using rotary friction welding process. Statistical analysis based on response surface methodology (RSM), microstructural examination using scanning electron microscopy with backscattered electron diffraction (EBSD) and mechanical tests were performed to investigate the friction weld joints. The results showed that friction time and rotation speed were the most effective parameters on the weld joint quality with the highest t-ration of − 4.27, where the maximum bending strength of 1406.9 MPa was obtained at 2000 rpm for 13 s friction time. Increasing friction time to 13 s resulted in remarkable decrease in grain size (about 35%) at the weld interface, which increased the hardness (350HV0.1) and elastic modulus (260 GPa).Graphical abstract

Predicting the ultimate tensile strength of AISI 1045 steel and 2017-T4 aluminum alloy joints in a laser-assisted rotary friction welding process using machine learning: a comparison with response surface methodology

Welding metal alloys with dissimilar melting points makes conventional welding processes not feasible to be used. Friction welding, on the other hand, has proven to be a promising technology. However, obtaining the welded joint’s mechanical properties with characteristics similar to the base materials remains a challenge. In the development of this work, several of the machine learning (ML) regressors (e.g., Gaussian process, decision tree, random forest, support vector machines, gradient boosting, and multi-layer perceptron) were evaluated for the prediction of the ultimate tensile strength (UTS) in joints of AISI 1045 steel and 2017-T4 aluminum alloy produced by rotary friction welding with laser assistance. A mixed design of experiments was employed to assess the effect of the rotation speed, friction pressure, and laser power over the UTS. Furthermore, the response surface methodology (RSM) was employed to determine an empirical equation for predicting the UTS, and contours maps determine the main interactions. A total of 48 specimens were employed to train the regressors; the 5-fold cross-validation methodology was used to find the algorithm with greater precision. The gradient boosting regressor (GBR), support vector regressor (SVR), and Gaussian processes regressors present the highest precision with a less than 3% percentage error for the laser-assisted rotary friction welding process. The GBR and SVR capability exceed the RSM’s accuracy with a coefficient of determination (R2) greater than 90.9 versus 83.2%, respectively.

Effect of faying surfaces and characterization of aluminium AA6063–steel AISI304L dissimilar joints fabricated by friction welding with hemispherical bowl and threaded faying surfaces

This work describes the effect of newly introduced faying surfaces on the microstructure and the mechanical properties of dissimilar weld joints of AA6063 and AISI304L alloys that are fabricated through the rotary friction welding process (RFW). The experiments were done as six different experimental methods (‘A’ to ‘F’) at 1300 rpm rotation, 18 MPa friction pressure (FP), 24 MPa upset pressure (UP) and 5 s friction time (FT) with the faying surfaces of hemispherical bowl and thread of 1 mm pitch on the weld specimens. The fabricated joints and the weld zones were characterized by macro and microstudy, energy dispersive X-ray spectroscopy (EDS) spectrums, tensile properties, Vickers microhardness, impact toughness and fractography. The results showed that these faying surface modifications strengthen the bonding between the weld specimens and influences the performance of the joints. The hemispherical bowl showed better results than the threaded surfaces. Axial shortenings were within the acceptable limit in the range of 20–27 mm. Macro and microstructural studies showed the defect-free weld joints and the strong bonding between AA6063 and AISI304L alloys. The hemispherical faying surface on AISI304L alloy formed a U-shaped weld interface (WI) in the dissimilar joints. EDS proved the formation of the Fe–Al intermetallic and the element ‘O’ at weld zone. The joint efficiency for all the methods was around ≥100%. Maximum tensile strength was recorded as 238 MPa for method F. The threaded surface showed good hardness property nearby WI, and method A yielded maximum impact toughness for the joint.

Interlayer Effect on Connection of Mild Steel ST37 and Stainless Steel 201 on Rotary Friction Welding

Friction welding is a type of solid state welding where the welding process is carried out in a solid phase to combine various types of ferrous and non-ferrous metals that cannot be welded by the fusion welding method but for welding different metals the welding results are less than optimal due to cracks on the surface of the welding results and differences in mechanical properties that cause the welding result to be brittle, therefore an interlayer is used. In this study, observations were made on the process and results of the joint friction welding using dissimilar metal material between mild steel ST37 and stainless steel 201 with copper interlayer. The results of the test will be a tensile test to see the maximum tensile strength and a hardness test to see the hardness value of the interlayer variation of 0.3 mm, 0.5 mm, 1 mm and without an interlayer. The conclusions obtained are: (1) The effect of the addition of an interlayer on the rotary friction welding process includes the friction phase, the forging phase and the results of welding parameters in the form of motor power, motor angular speed, the change in specimen length is greater without using an interlayer compared to using an interlayer while the duration of welding time is greater using an interlayer than without using an interlayer. (2) The maximum tensile test results were obtained at the 1 mm interlayer at 482.43 MPa and the maximum hardness test results obtained at the 1 mm interlayer were 321.34 VHN.

Effect of Laser Heat Treatment on the Mechanical Performance and Microstructural Evolution of AISI 1045 Steel-2017-T4 Aluminum Alloy Joints during Rotary Friction Welding

This paper evaluates the influence of laser power on the rotary friction welding (RFW) process to improve the mechanical performance and microstructural evolution of AISI 1045 steel and 2017-T4 aluminum alloy joints. As part of this evaluation, the absolute chemical determination of these materials was precisely measured using a GDOES bulk analysis. The application of laser power during friction welding is known as laser-assisted friction welding. To evaluate the effect of the energy from the laser on the rotary joining process of steel-aluminum, a laser-assisted rotary friction welding process was set up, and a design of experiments (DOE) applied. First, a DOE consisting of two factors at two levels was used to evaluate the effect of friction pressure and rotational speed on the hardness and tensile strength of the weldment. Then, a mixed DOE of three factors at two and three levels was implemented to investigate the effect laser heat treatment has on the process. It was concluded that the application of a laser heat treatment plays a significant role in the resulting mechanical performance and microstructural evolution of RFW steel-aluminum joints. Increasing both the ultimate tensile strength and the thickness of the Al(Fe, Cu) interface reaction layer between the joined materials.

MECHANICAL PROPERTIES ESTIMATION FROM TENSILE TESTING OF AA6063-AISI304L BIMETAL JOINTS FRICTION WELDED WITH DIFFERENT JOINING METHODS

This paper discusses the various joining methods with faying surface modifications used to join AA6063 and AISI304L dissimilar alloys by Rotary Friction Welding (RFW) process at different welding conditions mainly with friction pressure (FP), upset pressure (UP) and friction time (FT). This paper also studies the tensile behavior of the welded joints. The fabricated dissimilar joints were tested using universal testing machine against tensile load, and the mechanical properties of all 30 nos. of weld joints like elongation (%), strength coefficient ([Formula: see text]), strain hardening exponent ([Formula: see text]), strain hardening rate (TS/YS ratio), shear strength, etc. were calculated from the tensile testing results and plotted here with a standard error bar. Hollomon’s equation is considered here to study the stress and strain hardening relation and Von Mises yield criterion is considered for shear and yield stress correlation. Total elongation is also calculated from the initial and final length obtained during the tensile test. Since fracture ductility of the joints depends on the stress, strain, ‘[Formula: see text]’ and ‘[Formula: see text]’ values, it is important to study these mechanical properties and how the tensile results can be used for their estimation is detailed in this paper. The faying surfaces influence the mechanical properties as well.

Optimisation of the rotary friction welding process of titanium alloy rods

This paper presents a study on the performance behaviour of friction welded titanium alloy rods. The Ti6Al4V alloy rods were friction welded with continuous-drive friction welding using different combinations of process parameters. The welding speed ranging from 1600 to 2700 RPM and the applied pressure ranging from 25 to 140 MPa were utilized for the welding process. The weld joints and the parent material were examined for microstructure characterisation, Vickers hardness and tensile properties. The microstructure of the weld joint revealed fine equiaxed grains with complete recrystallization. The presence of martensitic grains was obtained at process parameter combinations of low welding speed and high pressure. The tensile tests conducted revealed that the weld joints of low speed and high pressure had improved tensile properties when compared to that of the parent material. The ultimate tensile strength of 1040 MPa with the elongation of 26.5 % was obtained at a speed of 1900 RPM and 80 MPa pressure. The micro-hardness tests revealed an increase in hardness across all the weld zones when compared to the parent material, with the maximum hardness obtained at the weld nugget. Further study was conducted to evaluate the effect of parameters on the weld joint integrity.

Evolution of interfacial contact during low pressure rotary friction welding: A finite element analysis

Development of rotary friction welding (RFW) is of critical importance for extending the RFW technology to join large-scale structures, such as rods/pipes for generator rotors and nuclear power plants. In this paper, finite element (FE) analysis is employed to analyze the thermal-mechanical process during low-pressure rotary friction welding (RFW), and the dynamic evolution process of interface contact is illustrated. Low-pressure RFW process of D50Re steel rod with a diameter of 100 mm is investigated by using the fully coupled thermal-mechanical FE analysis. In the analysis process, the two work pieces are regarded as two contacting entities, and a new method based on equivalent thermal expansion (TE) coefficient is proposed in order to study the dynamic contact behavior during low-pressure RFW. Three simulation cases, which consider no TE, real TE coefficient and equivalent TE coefficient respectively, are performed. It is shown from the comparison between the simulation results and the experimental data that, the equivalent TE coefficient is viable approach in the FE analysis to improve the prediction on the axial shortening and the welding torque. It was demonstrated that significant incomplete interfacial contact occurs during the friction stage in low-pressure RFW. The formation and expansion of the contact zone is in a thermo-mechanical fully coupled manner. Since the temperature is not uniform across the friction interface, the contact area is first formed in the high temperature area, and the expansion of the contact area occurs subsequently. When the temperature at the interface is uniform, almost full contact would be achieved over the friction interface. The modeling and simulation method proposed in this paper is helpful for understanding the underlying physical phenomenon during RFW process. If experimental tests can be extended to determine the equivalent TE coefficient, the accuracy and the reliability of the proposed simulation method in this paper will be further improved.

Friction welding of Aluminium Alloy 6063 with copper

Friction welding process is a forging welding process in which work piece are joined due to heat produced by friction between two joining surfaces and upset pressure is applied by non-rotating work piece. Joining of aluminum alloy with dissimilar material is important research area to focus on as maximum aircraft structures havexx Aluminum alloy frame and aerospace designers familiar with Aluminum alloy and its design considerations. After comparison of mechanical properties and application of light weight alloys aluminum alloys, tungsten, stainless steel and copper, copper selected as dissimilar material to join with Aluminum alloy AA6063. AA 6063 also known as architectural alloy selected based upon its properties. This dissimilar joint of AA6063 and Copper has application in electrical conductors as copper is good electrical conductivity and used in maximum electrical conductors. In this research work AA6063 joined with Copper successfully using Rotary Friction Welding process. Through process study effective process parameters like Friction Pressure, Upset Pressure, Spindle Speed, and Friction Time identified and their effect on weld joint strength were studied.Testing for measuring UTS of friction welded joint conducted. Using DOE tool optimized set process parameters for friction welding identified and their effect on weld joint strength studied experimentally. Maximum UTS of 222.787 MPa for Friction welded joint achieved, bend test also performed on friction welded samples.

Experimental Thermal Analysis in Rotary Friction Welding of Dissimilar Materials

Rotary friction welding process (RFW) is one of the most used processes in the world for manufacturing bimetallic components that require high mechanical strength. All process occurs in solid state at temperatures below the melting point of the involved materials, having as the main bonding mechanisms the diffusion and mechanical mixture. The purpose of this work was to carry out an experimental thermal analysis of the dissimilar joint AA6351 T6 aluminum and AISI 304L stainless steel during the friction welding operation through system of thermocouples. Gradients of temperature obtained had their data analyzed and recorded. Results of the experimental thermal analysis showed the behavior of the temperature in the bonding interface, how the dissipation occurs in the radial and longitudinal direction, heating rates, cooling, maximum temperatures reached, its relationship with the different stages of the process and the influence on mechanical properties of welded joint. This study is of great importance for relating the temperature distribution in the bonding interface with atomic diffusion and mechanical resistance of junction.

Finite element study on rotary friction welding process for mild steel

The purpose of study is to investigate friction welding of series of mild steel by using Finite element analysis by a 3D model made in order having a proper rotational speed and time friction. This Numerical analysis divided into two categories that is structural analysis, and thermal analysis. Structural analysis process parameters can also have divided 4 kinds that are frictional time, frictional pressure, deformation and rotational speed. The thermal analysis process parameters are dealing with and counted as heat flux, and temperature. Friction welding with three different rotational speeds (2000 RPM, 2500 RPM, and 3000 RPM) & three different friction time (150 s, 200 s, and 250 s) This study used SOLIDWORKS 2016 and ANSYS 17.2. SOLIDWORKS 2016 is the software used for designing work pieces’ geometry while ANSYS 17 is the software is used to analyzed finite element analysis on the work pieces. The second purpose of study is the numerical analysis would be compared with the experimental analysis. The experimental analysis is taken place at friction welding machine in the laboratory of technology production of the University of Riau. Based on the numerical analysis we can summarized that the faster the shaft rotates would resulting the higher the temperature generated, the higher the heat flux generated, & the higher the reduced of length. Also the influence of friction time shown that the longer the time of friction would result the lower the temperature generated, the lower the heat flux generated, the lower the reduced of length value. By compared the numerical and experimental analysis we can conclude that the difference reduced of length data between simulation and experimental happened because on simulation only input the friction pressure, while on experiment friction and forging pressure happened simultaneously. By interpolating the result with the melting point of mild steel (1350 °C ) we can gather the minimum requirement for getting a uniform weld temperature for each friction time, that were; 2650 rpm for 150 s friction time, 2852 rpm for 200 s friction time, & 3034 rpm for 250 s friction time.

Numerical simulation based upon friction coefficient model on thermo-mechanical coupling in rotary friction welding corresponding with corona-bond evolution

Numerical simulation method was employed to reveal the mechanism of manufacturing a rotary friction welding joint, in which a two-dimensional finite element model was constructed based on a comprehensive friction coefficient model to simulate the thermo-mechanical coupling during rotary friction welding. Experiments were focused on rotary friction welding of SUS304 in diameter of φ25 mm at 900 rpm under 80 MPa, of which the joint were studied on evolutions of temperature field, stress fields (i.e., both stress-Z and effective stress) and tensile strength corresponding with the corona-bond evolution. Thereafter, the simulation focused on the effect of rotation speed that varied as 500–2500 rpm, in which the minimum welding time necessary to cover a welding cycle was issued. The finite element model was shown valid by the consistency of comparison between simulation and experiment. Transition temperature fields (in contours) were verified in good agreement with transition morphologies of the joints as experimentally characterized by the corona-bonds. The results show that, rotary friction welding process can be classified into two stages: the corona-bond evolution and the plastic flow. The former stage is characterized by the corona-bond that develops and fills out the interface, in which the temperature is kept raising and the stress field kept varying; whereas the latter stage is denoted by the extrusion of flash that keeps forming at constant temperature and stress fields (i.e., both stress-Z and effective stress). The tensile test reveals that the latter stage makes negligible contribution to the joint strength, which falls in the range as 660–688 MPa as the welding time is regulated from 1.8 to 15 s. Thus, time consumed on former stage was ascertained to be the minimum welding time, which ranges in 1.5–2.9 s for SUS304 in φ25 mm of diameter welded under 80 MPa at the rotation speed of 500–2500 rpm.

Multi-objective optimization of high carbon steel (EN-31) and low carbon steel (SAE-1020) using Grey Taguchi method in rotary friction stir welding

PurposeNowadays, a rotary friction welding method is accepted in many industries, particularly for joining dissimilar materials as a mass production process. It is due to advantages like less material waste, low production time and low energy expenditure. The effect of the change in carbon contents in steel is studied experimentally in the rotary friction welding process, and a statistical model is developed. The Grey Taguchi method gives the single parameters optimization for all output responses. The paper aims to discuss these issues.Design/methodology/approachAn experimental setup was designed and produced to achieve the multi-response in single optimum parameters through Grey relational analysis. A continuous/direct drive rotary friction welding process is chosen in which transition from friction to the forging stage can be achieved automatically by applying a break. In this experimentation, high carbon and low carbon work-pieces with different carbon percentage were welded with rotary friction welding. Response tensile strength and micro-hardness of the design of the experiment are used to analyze the results.FindingsThe optimization of parameters has been performed with Grey relational analysis, and optimum parameters are friction pressure 40 kg/cm2, forging pressure 100 kg/cm2 and speed 1,120 rpm. GRA optimum parameters give 56.04 and 82.16 percent improvement in Tensile strength and micro-hardness, respectively.Practical implicationsHigh carbon steel (En-31) and low carbon steel (SAE-1020) are used in so many industrial applications. These materials are mostly used in the process like manufacturing, metallurgy, machinery, agricultural, etc. These practical applications have brought forward definite and notable economic benefits.Originality/valueIt provides a new framework to investigate the problems where multiple input machining variables and various output responses are obtained in single optimized parameters.

MICROSTRUCTURAL AND MECHANICAL ASPECTS OF FRICTION WELDED DISSIMILAR JOINTS FOR AERO ENGINE APPLICATION

Gas turbine engines demand material with unique properties like high-temperature oxidation and corrosion resistance, high specific strength, etc. All over the world material development to meet these requirements has led to the development of novel alloys. While Titanium base alloys are used in the low-temperature regime of the gas turbine engine, Nickel-basedsuperalloys are used for hot end components of the engine. With the increase in the temperature requirement for the turbine parts, the form of the Ni-based superalloys changed from wrought to cast superalloys. As an inherent process of investment cast superalloy blades and vanes which has serpentine passages for air cooling, these passages are required to be closed after casting. The numerous adapters also need to be joined on the cast superalloy casings for various instrumentation, lube oil ports. These cast superalloys are nonweldable and joining these pose a challenge. In this present investigation, the joining of the Nibasedsuperalloy BZL12Y and martensitic stainless steel AE961W using rotary friction welding process. The mechanical properties of the dissimilar joints were evaluated as per the ASTM standards. Microstructural features of various regions of welded joints using optical microscopy (OM) and scanning electron microscopy (SEM). The material is welded in different condition to obtain the maximum tensile strength of the weld joint. From this investigation, it was found that the combination of aging and h & t condition weld joint gives good strength and a stable hardness value. Correlation between tensile properties and microstructural features were analyzed and reported in this paper.

Microstructure and mechanical properties of a rotary friction welded tungsten heavy alloy

Abstract Tungsten heavy alloys (WHAs) are widely used in many aerospace and defence applications such as radiation shields, kinetic energy penetrators etc. In the current work, attempts were made to join WHA rods (8 mm in diameter) using rotary friction welding techniques. The WHA rods were prepared via conventional liquid phase sintering and had a two phase microstructure containing tungsten particles of spherical shape and surrounded by a solid solution matrix of Fe, Co and Ni. Rotary friction welding process parameters were successfully optimized and a sound weld with a narrow weld interface without any defects was obtained. The weld interface was found to be of a uniform width of around 150 μm throughout the weld interface and showed very fine fragmented tungsten particles with a refined matrix phase. Moreover, the thermomechanically affected zone (TMAZ) elongated tungsten particles were clearly seen to react normally to the compressive force direction. Further, the heat-affected zone width was so narrow that it was not detected in the current study. Microhardness at the interface showed increased hardness when compared with the base material indicating that the microstructural refinement occurred during friction welding. Tensile tests carried out at room temperature as per ASTM-E8, showed lower strength and ductility when compared with the base material (tested along the hot-working direction). The fractography of the fractured surface of the base material and weld sample confirmed that the ductile mode of fracture had occurred.

A heat flux model for rotary friction welding of 304 stainless steel

The objective of the present study is to establish an accurate model for heat flux during continuous-drive rotary friction welding (RFW) of 304 stainless steel. RFW experiments were conducted over a wide range of friction pressure (25 MPa ∼ 160 MPa) and rotation speed (500 rpm ∼ 2000 rpm), which are the main parameters that affect the heat flux during continuous-drive rotary friction welding process. The evolution characteristics of experimental heat flux data were analyzed. Then, the influence of friction pressure and rotation speed on the characteristic value of heat flux was investigated. Based on the experimental heat flux data, a model for heat flux as a function of friction pressure and rotation speed was constructed. Finally, the model was proved to be accurate through additional experiments.

Modeling of rotary friction welding process based on maximum entropy production principle

The interfacial transition point isolated by maximum entropy production principle (MEPP) was used to construct a two-dimensional (2D) finite element (FE) model of continuous-drive rotary friction welding (RFW) with GH4169 superalloy. The transition point from sliding friction to shear friction was calculated based on the equal entropy of these two kinds of heat liberation mechanisms at this point. The FE model was shown valid by the consistency of comparison between simulation and experiment. The simulation issued an interfacial distribution of non-uniform heat intensity that determined the corona bond, which corresponded to higher temperature zone over the transition temperature. The influences of linear speed and friction pressure on welding time were examined, which showed that a shorter welding time could be acquired when the linear speed was about 1.96 m/s and the friction pressure is larger.

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.

Thermal Model of Rotary Friction Welding for Similar and Dissimilar Metals

Friction welding is one of the foremost welding processes for similar and dissimilar metals. Previously, the process has been modeled utilizing the rudimentary techniques of constant friction and slip-stick friction. The motivation behind this article is to present a new characteristic for temperature profile estimation in modeling of the rotary friction welding process. For the first time, a unified model has been exhibited, with an implementation of the phase transformation of similar and dissimilar materials. The model was generated on COMSOL Multiphysics® and thermal and structural modules were used to plot the temperature curve. The curve for the welding of dissimilar metals using the model was generated, compared and analyzed with that of practical curves already acquired through experimentation available in the literature, and then the effect of varying the parameters on the welding of similar metals was also studied.

Calculating the energy required to undergo the conditioning phase of a titanium alloy inertia friction weld

Inertia friction welding (IFW), a type of rotary friction welding process, is widely used across aerospace, automotive and power-generation industries. The process considers a specialist rotary friction welding machine, which asks for the critical process parameters of inertial mass, initial rotational speed and applied pressure, to complete the relevant weld. The total kinetic energy available to the system can be calculated from basic physical relationships for the kinetic energy stored in a flywheel. This kinetic energy must be converted partly to heating the specimen at the interface, and partly to mechanical work via deformations. A finite element (FE) numerical model has been developed to predict the steady-state thermal profiles formed at the onset of mechanical deformation. Therefore, the amount of this total available energy for the process which is applied to the heating of the component at the interface through frictional contact has been estimated. Thus, the available energy left to produce the mechanical deformation via the flash formation can be calculated by subtracting the thermal energy from the total energy. This is of importance to the manufacturing engineer. A method of validating the FE modelling predictions was proposed using high-speed photography methods during the process to understand the rotational speed of the moving part at the instant that the steady-state deformation commences. Results from FE modelling and experiment suggest that the width of the steady-state thermal profile formed through the IFW, and the time taken to reach steady-state is strongly dependent upon the applied pressure parameter.