Search

Continuous drive friction welding process is widely used in various industrial applications to assemble shafts, tubes, and many other components. This paper's motivation was developing a CDFW model using the Finite Element Method (FEM). The coupling of the process's thermal and mechanical behaviors was considered during the simulation by COMSOL Multiphysics®. The construction of phase transition curves for Al6061 allowed determining several temperature-dependent thermophysical properties of the material. These properties are then injected in a second simulation to study the temperature evolution during welding. Subsequently, these results are compared and analyzed with the experimental outcomes. Excellent comparability between the model and experimental results was achieved. A unique phenomenon in the welding temperature profile was observed and explained through the model and experimental results interpretation. [ABSTRACT FROM AUTHOR]

The present study aimed to enhance the efficiency and efficacy of the Al/Cu joint production process implemented by the company VEMID Ltd., Jagodina, Serbia, by attaining sound joints within a very short welding time. For this purpose, the present study aimed at investigating the accuracy and the quality of the continuous drive friction welding (CDFW) process, as well as the optimum combination of CDFW parameters with highest joint efficiency in terms of investigated properties. The accuracy was estimated through an analysis of temperature–time curves recorded during CDFW using an infrared camera. The quality was evaluated through an investigation of the properties of Al/Cu joints produced using different friction (66.7, 88.9, and 133.3 MPa) and forging (88.9, 222.2, and 355.6 MPa) pressures and a constant total welding time (4 s) and rotational speed (2100 rpm). Thermal imaging with an infrared camera demonstrated that the actual total welding time was 15% longer compared to the nominal value. This was attributed to the slow pressure response of the pneumatic brake system. The relative changes in the maximum surface temperature (TMS) during the CDFW process corresponded to changes in welding pressures, indicating the potential of the thermal imaging method for monitoring and assessing this process. A preliminary investigation demonstrated that Al/Cu joints produced using welding pressures less than 88.9 MPa often displayed the presence of non-joined micro-regions at the Al/Cu interface and a significant thickness of interfacial Al2Cu (up to 1 µm). However, when friction pressure was set at 66.7 MPa, an increase in the forging pressure to 222.2 MPa eliminated the presence of non-joined micro-regions and reduced the thickness of Al2Cu to 0.5 µm on the average level. These Al/Cu joints achieved the highest joint efficiencies in terms of strength (100%) and ductility (61%). They exhibited an electrical conductivity higher than 92% of the theoretical value. A further increase in any welding pressure produced similar or deteriorated properties, accompanied by an increase in the consumption of raw materials and energy. Such turn of events was counterproductive to the original goal of increasing the efficiency and efficacy of the CDFW process. [ABSTRACT FROM AUTHOR]

The continuous drive friction welding of 6061-T6 Al and copper was investigated herein. The results show that with an increase in rotation speed, the width of the welded zone was gradually increased with the generation of higher temperatures, and the grain size in the dynamic recrystallization zone on the Al side first decreased and then increased due to the combined effect of heat and force. The microhardness on the bonding surface was significantly greater than that of the base materials due to the presence of intermetallic compounds, and there was a softening zone on both sides of the bonding surface, which was progressively more significant with an increase in the rotation speed. The ultimate tensile strength (UTS) of the welded joints first increased and then decreased with an increase in rotation speed. When the rotation speed was 1000 rpm, the UTS was at its peak value of 212 MPa, which reached 73.1% of the strength of the 6061-T6 Al base material. [ABSTRACT FROM AUTHOR]

This paper aims to analyze the effect of pressure and holding time in the upset stage on tensile strength and macro-microstructures of continuous drive friction welded (CDFW) joints of aluminum alloys A6061. Friction weld specimens were welded using variations of upset pressure (40, 80, 120 MPa). The upset holding time was varied from 3, 10, to 20 seconds. Tensile strength test was conducted based on the AWS standard. The result showed that the higher upset pressure and the longer holding time in the upset stage are able to reduce the porosity of the CDFW weld joint and cause a higher tensile strength of the specimens. Meanwhile, from macro-mic restructures observation results, it was found that the specimen with maximum tensile strength has a wider partly deformed area (ZPD) and finer grains in the center of the specimen longitudinal section compared to those of the specimens with minimum tensile strength. It was occurred due to plastic deformation as the result of the higher pressure and the longer holding time in the upset stage. Fracture surface observation results indicate that in the specimen with a higher upset pressure and a longer holding time, has inflated fracture surface and the fracture zone exists in the heat affected zone, not in the interface like that of the specimen with lower tensile strength due to the lower upset pressure and the shorter holding time.

In this paper, the joints between Al and Cu bars were fabricated by continuous drive friction welding. The microstructures and the compositions of the composites were analyzed by SEM, EDS and XRD. The surface temperature was observed using an infrared thermographic camera. The interface temperatures were suggested in the range of 648~723 K at different welding parameters. The interdiffusion between Al and Cu atoms is extraordinarily rapid, as the interdiffusion coefficients could reach 7.8 × 10−12 m2/s. Intermetallic phases Al2Cu and Al4Cu9 were identified in all samples in view of the XRD and EDS analyses. The effective Gibbs free energy change of formation model was proposed to predict the Al–Cu compound formation at solid-state interface, and the calculation combined with kinetic factors showed that Al2Cu (Al side) and Al4Cu9 (Cu side) appeared first.