Vibrations in friction welding

Investigation of the joining technology of 3D-printed parts into a large physical model has become an important research topic. Rotary friction welding (RFW) is one of the friction welding methods. Understanding the weld interface temperature changes in the weld center zone during RFW is critical because it is related to the weld quality of the welded parts using RFW. Traditionally, the number of revolutions is constant in the RFW. However, rare investigations focus on the fatigue specimen fabricated by RFW with variable rotational speed. This study used RFW with varying rotational speeds to fabricate fatigue specimens. The ANSYS software was used to predict the temperature history of rotary frictionally welded dissimilar polymer rods fabricated by a computer numerical control (CNC) turning machine with variable rotational speed. The RFW experiment of ABS/PC dissimilar polymer rods was conducted to investigate the temperature history and compared with the simulation results. It was found that the temperature history profiles were in good agreement with the experimental and simulation results. Compared with the weld interface heating rate obtained from the experimental results, the simulation results has average discrepancy rate about 4.48 %. Compared with the maximum temperature of the weld interface obtained from the experimental results, the simulation results has average discrepancy rate about 3.16 %. The fatigue life can be increased by approximately 1.4 times. Finally, a database of rotary frictionally welded dissimilar polymer rods fabricated by a CNC turning machine with variable rotational speed was proposed. The average Shore A surface hardness at the weld interface was enhanced by approximately 18 % compared to the base ABS material.

Model development for numerical analysis of the bonding strength for friction welded lightweight structures

Three friction welding processes are compared for temperature, stresses and strains, as well as strain rates developed in the early phases of the processes, which are essential in their successful development. These are friction stir welding (FSW), linear friction welding (LFW) and rotary friction welding (RFW). Their common characteristic is the use of friction to generate adequate energy and raise temperature locally in order to create favorable conditions for welding at the interface between two parts. Although the mode of movement is different for each one of them, welds are produced through plastic deformation. The Lagrangian and coupled Eulerian-Lagrangian numerical models developed have produced results which are in qualitative agreement with experiments and have shed a light on the commonalities of these friction welding processes.

Rotary friction welding (RFW) has no electric arc and the energy consumption during welding can be reduced as compared with conventional arc welding since it is a solid-phase welding process. The RFW is a sustainable manufacturing process because it provides low environmental pollution and energy consumption. However, few works focus on the reliability of dissimilar polymer rods fabricated via RFW. The reliability of the frictionally welded components is also related to the ambient temperatures. This work aims to investigate the effects of ambient temperature on the mechanical properties of frictionally welded components of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) dissimilar polymer rods. It was found that the heat-affected zone width increases with increasing rotational speeds due to peak welding temperature. The Shore A surface hardness of ABS/PC weld joint does not change with the increased rotational speeds. The Shore A surface hardness in the weld joint of RFW of the ABS/PC is about Shore A 70. The bending strength was increased by about 53% when the welded parts were placed at 60–70 °C compared with bending strength at room temperature. The remarkable finding is that the bending fracture position of the weldment occurs on the ABS side. It should be pointed out that the bending strength can be determined by the placed ambient temperature according to the proposed prediction equation. The impact energy was decreased by about 33% when the welded parts were placed at 65–70 °C compared with the impact energy at room temperature. The impact energy (y) can be determined by the placed ambient temperature according to the proposed prediction equation. The peak temperature in the weld interface can be predicted by the rotational speed based on the proposed equation.

This work investigates the microstructure evolution during the rotary friction welding (RFW) of Inconel 718 alloy. A cellular automata (CA) approach is implemented to evaluate a cylindrical component (at weld center and edge wall), predicting dynamic recrystallization (DRX) and grain size of friction welds. The input variables for RFW were rotational speed (500, 1000, and 1200 rpm), feed rate (2 mm/s), and feed distance (3.6 mm). The CA model is based on the Laasraoui-Jonas model and explains intricate grain transformation in terms of microstructure, temperature, strain, and strain rate. Calculated grain consists of very fine grain structure at the stir zone followed by the thermo-mechanical affected zone, where partial recrystallized microstructure was present. The average grain size was 2.5 µm, which is comparable to reported experimental values. The grain analysis revealed that temperature and strain are most affecting factors to attain a refined microstructure. The strain rates predicted for both center and edge locations of the weld were found to be higher as rotational speed increased. A steady strain distribution is noted at greater temperature for all the rotational speeds. The results of this work contribute toward the understanding of microstructure and mechanical response for RFW of Inconel 718.

Controlling martensite and pearlite formation with cooling rate and temperature control in rotary friction welding

Experimental analysis of rotary friction joining process by EN1A bright mild steel under normal air and wet environment condition

Optimizing weld strength and microstructure in CP-titanium and 304 stainless steel friction welds with chromium interlayer

Recently, rotary friction welding has been used to join magnesium alloys. FRW uses friction heat to bond magnesium alloys with aluminium alloys. Combining these light alloys can provide many promising applications in the industry. The welding parameters such as friction and upsetting force, rotational speed, and welding time play a significant role in determining the joint strength. The paper presents a new approach to multi-objective optimisation of friction welding process parameters for AZ91D/AA6082 alloy joints. Multi-objective optimisation is based on artificial neural networks and genetic algorithms as non-conventional AI techniques. The methods were used to determine the following optimal welding process parameters: friction force, upsetting force and friction time for simultaneously maximised tensile strength and minimised metal loss (shortening) during welding. The ultimate tensile strength and metal loss of the friction welding joints were studied numerically and experimentally. Moreover, the influence of welding parameters on the ultimate tensile strength and shortening of friction joints was also studied. A genetic algorithm successfully found a set of welding parameters for which the joint strength increases from 24 to 81 MPA and the joint shortening decreases from 8.25 to 0.23 mm. The results show that a low friction force and upsetting force give a high value of tensile strength and the lowest shortening of the bimetal joints.

Dissimilar joining using friction welding is demanding for various applications. Friction welding makes it possible to weld incompatible materials. In the present investigation, carbon steel to high strength steel dissimilar materials was joined using rotary friction welding. The interface characteristics were identified according to the welding conditions. The welding conditions were optimized to observe the intermixing zone width at the weld interface. The major influencing welding parameters of friction pressure, upsetting pressure, and friction time was selected as input factors and intermixing zones as the response factor. The intermixing zone's width increased with the increase of friction pressure and upsetting pressure along with the friction time. The intermixing zone microstructural analysis revealed the mixed layers of carbon steel and high-strength steel materials in several widths.

Mechanical behavior of rotary friction welding joints composed of laminated veneer bamboo substrate and bamboo dowel

Rotary Friction Welding (RFW) is a solid-state welding process that is becoming increasingly popular due to advantages such as low weld heat input, high production efficiency, ease of manufacture, and environmental friendliness. Rotary friction welding can weld materials that are difficult to fuse using fusion welding techniques. The main objective of this study is to join SA 213 T12 and SA 213 F12 low alloy steel (LAS) tubes using a rotary friction welding process and to optimise welding parameters such as friction pressure, forging pressure, and rotating speed. To optimise the welding conditions, the response surface method (RSM) was applied. Empirical relationships were developed to predict tensile properties such as tensile strength (TS), yield strength (YS), elongation (EL), notch tensile strength (NTS), and notch strength ratio (NSR). Using the test results, the tensile properties of the rotary friction-welded low alloy steel (LAS) tubes were determined. The optimum process parameters for better tensile properties of the rotary friction welded joint are found to be rotation speed (N) 60 rps, friction pressure (FF) 0.851 MPa/s, and forging pressure (FOF) 0.851 MPa/s.

Microstructural and mechanical behaviour of friction welded SS316L components fabricated by selective laser melting

The main objective of this investigation is to optimize the rotary friction welding (RFW) parameters for maximizing the tensile strength (TS) and weld interface hardness (WIH) of rod to plate joints of different grades of low carbon steel and analyze the effect of RFW parameters on TS and WIH of joints. AISI 1018 and AISI 1020 grades of low carbon steel are joined to develop unsymmetrical rod to plate joint using RFW for automotive applications. RFW being a solid-state welding (SSW) was employed to avoid the problems in fusion welding and development of unsymmetrical joints such as solidification cracking, wider heat affected zone (HAZ) and distortion. The RFW parameters specifically friction pressure/friction time (FRNP/FNRT), forging pressure/forging time (FRGP/FRGT) and rotational speed (rps) were optimized using response surface methodology (RSM) to maximize the strength and hardness of rod to plate joints. The three factor – five level central composite design (3 × 5 - CCD) consisting of less experiments was employed for designing experimental matrix. The tensile strength and microhardness tests were performed to evaluate mechanical performance of rod to plate joints. The numerical and graphical optimization techniques of RSM were employed to optimize the RFW parameters. The 3D response surfaces were developed which show the optimum conditions of RFW parameters. The effect of RFW parameters on TS and WIH of rod to plate joints was analyzed from 3D response surfaces. The microstructural features of optimized rod to plate joint were analyzed using optical microscopy. The fractured surfaces of rod to plate joints were analyzed using scanning electron microscopy. Results showed that rod to plate joints developed using FRNP/FRNT of 3.71 MPa/s, FRGP/FRGT of 3.71 MPa/s and RTSP of 19.99 rps exhibited higher TS and WIH of 452 MPa and 252 HV0.5 respectively. The higher TS and WIH of rod to plate joints is attributed to the evolution of finer grain structure in weld zone and narrower HAZ. The RTSP revealed greater effect on TS and WIH of rod to plate joints followed by FRGP/FRGT and FRNP/FRNT.

Orientation (EBSD) and transmission electron microscopy have been used to study the structure and orientation relationships of α' and γ-phases in medium-carbon steels during rotational friction welding. It is shown that, as a result of phase recrystallization, martensite with interlayers of the γ phase is formed in the structure of the welded joint. The formation of secondary (reverted) austenite was established by the form of the spectrum of angular deviations of interfacial boundaries. It is shown that, in this case, an orientation relation close to the Bein one is realized between the crystals of the α and γ phases.