Friction Welding Of Aluminium Alloys Research Articles

Structure–Property Correlation between Friction-Welded Work and Hardened Al-4.9Mg Alloy Joints

Friction welding of aluminum alloys holds immense potential for replacing riveted joints in the structural sections of the aeronautical and automotive sectors. This research aims to investigate the effects on the microstructural and mechanical properties when AA5083 H116 joints are subjected to rotary friction welding. To evaluate the quality of the welds, optical and scanning electron microanalysis techniques were utilized, revealing the formation of sound welds without porosity. The microstructural examination revealed distinct weld zones within the weldment, including the dynamically recrystallized zone (DRZ), thermo-mechanically affected zone (TMAZ), heat-affected zone (HAZ), and base metal (BM). During the friction-welding process, grain refinement occurred, leading to the development of fine equiaxed grains in the DRZ/weld zone. Tensile testing revealed that the weldment exhibited higher strength (YS: 301 ± 6 MPa; UTS: 425 ± 7 MPa) in the BM region compared to the base metal (YS: 207 ± 5 MPa; UTS: 385 ± 9 MPa). However, the weldment demonstrated slightly lower elongation (%El: 13 ± 2) compared to the base metal (%El: 15 ± 3). The decrease in ductility observed in the weldment can be attributed to the presence of distinct weld zones within the welded sample. Also, the tensile graph of the BM showed serrations throughout the curve, which is a characteristic phenomenon known as the Portevin–Le Chatelier effect (serrated yielding) in Al-Mg alloys. This effect occurs due to the influence of dynamic strain aging on the material’s macroscopic plastic deformation. Fractography analysis showcased a wide range of dimple sizes, indicating a ductile fracture mode in the weldment. These findings contribute to understanding the microstructural and mechanical behavior of AA5083 H116 joints subjected to rotary friction welding.

High-frequency linear friction welding of aluminum alloys to stainless steel

Joining of 5083 and 6063 aluminum alloys to 304 stainless steel was successfully achieved by high-frequency linear friction welding working at 245 Hz with varied friction pressure and time, which affect the heat input. Increasing the friction pressure and friction time resulted in the softening of aluminum alloys, which facilitated plastic flow and subsequent squeezing behavior. The morphology of the intermetallic compound layer, dependent on the plastic flow, determined the performance of 5083 aluminum alloy/steel joints. Excessive friction pressure and time led to inefficient welding in 6063 aluminum alloy/steel joints because the softening and squeezing behavior of the heat-treatable alloy was susceptible to the heat input. Highly efficient joints were obtained in a short duration, i.e., 1 s, through the formation of a thin intermetallic compound layer at the interface below 500 and 50 nm for 5083 and 6063 aluminum alloy/steel joints by controlling the appropriate friction pressure. High-frequency linear friction welding was demonstrated to be effective for the sound joining of various materials by controlling the friction pressure.

High-frequency linear friction welding of aluminum alloys

We developed High-Frequency Linear Friction Welding (HFLFW) operating at 250 Hz, which is larger than conventional LFW methods, to realize welding aluminum alloys. In order to establish the fundamental HFLFW process for the welding of Al alloys, the relationship between the mechanical properties and microstructure of the HFLFW joint was investigated for both 6063 and 5052 Al alloys, which have different strengthening mechanisms. Sound welds were achieved for both 6063 and 5052 Al alloys. The change in the shape of flash with increasing process time indicated that the material flow in the joint was largely affected by the material properties such as proof stress at high temperature and thermal conductivity. Further, the hardness increased and refined grains were observed at the interface of the 6063 Al alloy joints welded in the low-heat-input condition, which led to a higher joint strength at a shorter process time. The size of the refined grains was about 100nm, as observed by transmission electron microscopy. Our findings reveal that a high frequency is effective and HFLFW is a promising process for the welding of precipitation-hardening aluminum alloys with a high joint strength owing to the less heat effect during the process.

Shear coefficient determination in linear friction welding of aluminum alloys

Abstract In the present study, a combined experimental and numerical investigation on Linear Friction Welding (LFW) of AA2011-T3 aluminum alloy was carried out in order to find the temperature dependent shear coefficient to be used in a 3D numerical model of the process. Torque, oscillation frequency and pressure were acquired in order to calculate the shear stress at the interface. A numerical thermal model was used to calculate the temperature at the interface between the specimens starting from experimental temperatures acquired through a thermocouple embedded in the LFW specimens. Finally, the calculated shear coefficient was used to model the contact between the two specimens in a dedicated 3D, Lagrangian, thermo-mechanically coupled rigid-viscoplastic numerical model of the LFW process. A narrow range of variation of the shear factor vs temperature curve was found with varying LFW process parameters and good agreement was obtained for the temperature prediction of the 3D model of the process.

Residual stresses in Linear Friction Welding of aluminium alloys

In the present study, the residual stresses distribution in the Linear Friction Welded (LFW) pieces were studied using Finite Element (FE) simulation and high energy synchrotron X-ray diffraction. Fully-coupled implicit thermo-mechanical analysis simulation procedure was employed, with semi-automatic re-meshing using Python scripting to accommodate large deformation and output contour tracking methods for extracting deformed configurations. Model validated by the multi-detector polychromatic synchrotron X-ray experimental data were used to study the distribution of residual stresses distribution in the Linear Friction Welded (LFW) pieces to provide a general function to describe the residual stresses distribution. A characteristic length scale was found in the plot.

Dissimilar friction welding of aluminium alloys to other materials

Friction welding makes it easier to set welding conditions and also confers greater reproducibility than other welding processes. Through being a solid-phase process, friction welding moreover makes it relatively easy to join dissimilar materials. Other advantages of friction welding include good operability, the lack of any need for special skills, and a convenient capability for incorporation in assembly lines without showers of sparks and similar hazards being generated. Friction welding is therefore extensively used in a wide variety of industries, such as automotive engineering, printing, etc. Joining of dissimilar materials as a characteristic friction welding application has been well researched,1 reported,2 and thoroughly explained with reference made to practical examples.3 In the current situation of materials development advancing apace in pursuit of various objectives, available data relating to joining of dissimilar materials remains scant. To meet resource- and energy-saving objectives, machinery and plant, transport machinery, etc. are now required to embody lighter weight in a well-established trend that can only serve to expand the use of light metals. Compared with ferrous metals, however, friction welding of light metals has been little documented.

アルミニウム合金と銅の摩擦圧接継手における金属間化合物形成およびその継手効率への影響

Friction welding of aluminum alloys to copper was carried out in order to examine the weldability with particular reference to the effect of the intermetallic formation at the weld interface. The maximum joint efficiencies of A1050, 5000 and 6000 series alloys to copper were more than 80 %, while those of 2000 series and A7075 alloys joints were less than 50 % and scattered widely. For joints of A2024 and 5000 series alloys which contain rather high magnesium content, intermetallic compounds of Al-Cu-Mg system were formed at the weld interface in addition to that of Al-Cu system. In the other joints, only intermetallic compounds of Al-Cu system were formed. A mixing layer, in which pieces of copper and intermetallic compounds were incorporated into aluminum alloy, was formed near the weld interface. The mixing was very intense, in the joints with low efficiency, namely joints of A2011, A2024 and A7075 to copper, and these joints were fractured in this mixing layer and at the weld interface. On the other hand, the joints with high efficiency, namely joints of A5052 and A6061 to copper, had thin and even mixing layer. The mixing layers observed in the joints of A1050, A2017, A5056 and A6063 to copper were thinner than those of the other joints.

Friction welding of aluminium alloys hardened by heat treatment and cold working

Friction welding of aluminium alloys hardened by heat treatment and cold working