Papers by Keyword: Dissimilar Material

Abstract: This study presents conducted heat simulations and experimental jointing flat-plate of aluminum alloy 6061 and SUS 304. Temperature is simulated by the COMSOL software in three states: (1) Preheat the Friction Stir Welding (FSW) by TIG welding, (2) Thermal contact resistance between Aluminium and steel, and (3) The welding process using stiring friction is simulated. The simulations intended to predicting the temperature which is used for preheat and welding process to ensuring the required solid-state welding. The temperature is also determined and checked by a thermal imager comparing with simulation results. Besides, the results of tensile strength is carried out. The Box - Behnken method is used to identify the relationship between the welding parameters (rotation, speed and offset), temperature and tensile strength. The maximum tensile strength is 77% compared to the strength of aluminum alloy. The optimal set of parameters for the process is n = 676 rpm, v = 46 mm / min and x = 0.6 mm. The optimizing welding parameters to achieving good quality of welding process are described. SEM images to determine some properties of welding materials. This is also the basis for initial research to identify some defects in welding of two different materials (IMC thickness and interconnected pores) and the cause of these defects.

Abstract: In the dissimilar materials and dissimilar thin thickness sheets joining, welding current and welding time parameters of resistance spot welding (RSW) effect weld ability. RSW used for joining thin plate less than 1000 μm is called micro-resistance spot welding (μRSW). The objective of this article is to study the effect of welding current and welding time to the joining dissimilar thin thickness materials and the microstructure of a weld joint. The thickness of Al 1100 is 400 μm, and KS 5 Spring Steel is 200 μm. Welding parameters are Cycle Time 0.5, 1, 1.5, Welding Current 1kA and 2 kA, and holding time 10 second. Welding current 1kA, Cycle time of 0.5 produce maximum shear load of 227.4 N and fracture area of 6.644 mm². Welding current 2 kA, cycle time of 1.5 affect maximum load of 222.7 N and fracture area of 10.559 mm². Welding parameters lead to the majority fracture on aluminum material. The welding current and cycle time do not significantly affect maximum shear load and fracture area.

Abstract: A research study on the fatigue performance of hybrid adhesive joints was carried out to investigate the fatigue performance of adhesive joint and hybrid adhesive joint using dissimilar material. A 3 mm thin plate of aluminium A7075 and stainless steel 304 are used as the adherend material for experimental test and the adhesive used was high performance Araldite epoxy adhesive. Maximum fatigue life was achieved for the hybrid adhesive joint with an optimum overlap length of 59 mm and the adhesive thickness of 0.2 mm. The fatigue damaged occurs on the adherend surface for adhesive joint and adherend crack for hybrid adhesive joint. Results showed an increment of fatigue life with shear stress reduction.

Abstract: In order to assess the safety and reliability of lap joint structures with dissimilar materials in aircraft, the mixed structure of CFRP and 2A12 was taken as an example, and a calculation model that based on the boundary element method was provided to simulate the galvanic corrosion. Depend on this, the research in the influence of the electrolyte concentration and the film thickness on the corrosion current density and potential distribution on the surface of simulation structures was developed. Meanwhile, the measured data was also used to verify the accuracy of the output result of the model. The comparsion result shows that outputs of the model are in good agreement with experiment datas. This model can be used to predict the galvanic corrosion in the lap joint structure in aircraft, thus minimizing the potential threats caused by corrosion to the flight safety.

Abstract: Welding parameters are directly influenced by the work material properties. Thermal properties such as thermal conductivity and melting point are very important to estimate the range of power required and the allowable scanning speed. However, when two or more different materials are involved, modifying lasing parameters are not enough to counter the problems such as imbalance melting region and weak adhesion of contact surface. To counter this problem, the characteristics of welding beads formation for both materials need to be clarified. In this study, comparison of welding beads constructed using the same scanning parameters were done to understand the different and similarity of melted region for the both materials. Actual welding of the both materials were done under different offset distance to obtain a balanced melting area and well mixed melting region.

Abstract: The welding between Fe-Al intermetallic compound and high-strength steel was done via SPS technology. Microstructure, elements concentration and micro-hardness of welding joint were examined. The results indicated that there was no obvious welding heat-affected zone in both Fe-Al intermetallic compound and high-strength steel. The HAZ microstructures of high-strength steel were mainly martensite. In Fe-Al intermetallic compound, the grain size of heat-affected zone was larger than that of base metal and the density of heat-affected zone was lower than that of base metal. Besides, the grains of base metal had deformation phenomena. The welding joint had steady performance and the connection was reliable. Under the influence of chemical potential differences, unidirectional impulses discharge current and axial pressure, elements diffused perfectly in a short period of time.

Abstract: Laser joining for dissimilar materials between metals plate and polypropylene plate using a newly developed insert sheet was investigated. It was not possible to join the plate of various metals to the nonpolar plastic plate such as the polypropylene directly under the various laser-irradiation conditions. However, the use of insert sheet held between the metal plate and the polypropylene plate made it possible to join each metal plate to polyethylene plate by laser-irradiation. The joining strength increased with the increase in the input energy by laser-irradiation, and the joining strength cloud be improved since the reactivity between each metal and the insert material allows improvement by giving the insert material polarity with such as a-NH₂ group, -COOH group.

Abstract: Several rotating rates and welding speeds were chosen to joint 6063/3A21 dissimilar aluminum alloys, tensile strength of the welds were measured to analyze effect of welding parameters on weld performance. Results show that tensile strength of the weld is better than the base material. Weld tensile strength will decrease under a too high or too low welding speed while effect of rotating rate on weld strength is relatively small. The weakest position is at heat affected zone at 3A21 side after T6 post weld heat treatment.

Abstract: The dissimilar welds between magnesium alloy and aluminum alloy formed by friction stir welding has been investigated. The results show that the cavity and tunnel defect often appear in the welds, and the formation of fragile intermetallic compounds which exhibit virtually no ductility and lower strength cause the poor property of the welds during FSW.

Abstract: Laser transmission microjoining of two dissimilar materials has become a very significant technique. In this research, a numerical method is developed using finite element technique to determine the condition of joining two dissimilar materials namely Polyethylene terepthalate (PET) and titanium. First the model is used to optimize the laser parameters like laser traveling speed and power to obtain good bonding. A good combination is achieved at the power of 8W and laser traveling speed at 150mm/min.After the verifications, the profile of residual stress of the laser microjoint has been calculated using the developed model. The residual is low near the centerline along the traveling laser beam, and a higher values is away from the centerline at the x-direction shown by the contours on the PET surface. Higher residual von Mises stress near the centerline along the traveling laser beam and the stresses reduce as the distance away from the centerline.