Papers by Author: Hsuan Liang Lin

Abstract: In the metal inert gas (MIG) weld-brazing process, the lap-joint welds between 5052 aluminum alloy and automotive galvanized steel sheet were achieved employing an automatic MIG welding machine. The different percentage of helium (He) gas addition to pure argon (Ar) shielding gas was selected to investigate the performance of lap-joint welds such as appearance of weld bead surface, weld bead geometry, microstructure, tensile strength, fracture surface of welds and thickness of intermetallic compounds (IMCs) layer between the dissimilar materials in the brazing zone. The results showed that the lap-joint welds produced by adding 5% and 10% He gas to Ar shielding gas were provided with better performance of specimens. The average tensile strength of lap-joint welds between 5052 aluminum alloy and automotive galvanized steel sheet is 206.23 MPa. In additions, the amount of porosity in the fusion zone that specimens produced by using 10% He addition to Ar-based shielding gas is less than others. It can be found that the thickness of IMCs layer between the weld bead and automotive galvanized steel sheet from 3.30 μm to 4.90 μm.

Abstract: The purpose of this work is to investigate the effects of activating flux on the penetration, depth-to-width ratio (DWR), angular distortion and hardness of Inconel 718 alloy and AISI 304 stainless steel (SS) dissimilar welds in the tungsten inert gas (TIG) welding process. In the activated TIG (A-TIG) process, the single component fluxes such as SiO₂, NiO, MoO₃ and MoS₂ and the mixed component fluxes that using 50 % of each single component flux to create six new mixtures were used in the experiment. The experimental results showed that the A-TIG welds coated with 100% SiO₂ flux was provided with best DWR of dissimilar welds. In addition, the experimental procedure of A-TIG welding process not only produced a significant increase in penetration and DWR of weld bead, but also improved the angular distortion and hardness of Inconel 718 alloy and AISI 304 SS dissimilar welds.

Abstract: The purpose of this work was to investigate the effect of activating fluxes and welding parameter to the penetration and depth-to-width ratio (DWR) of 6061 aluminum alloy welds. Bead-on-plate argon gas tungsten arc (GTA) welding process was made on 6061 aluminum alloy of plate without filling metals. The activating fluxes used in the experiment were CaO, ZnO, SiO₂, TiO₂, Al₂O₃, Cr₂O₃, CaF₂ and Na₂CO₃. Based on the higher penetration of weld bead and welding arc voltage, four fluxes were selected to create three new mixtures using 50% of each original fluxes. The mixed fluxes were used to investigate the effect to the welding penetration. Finally, The Taguchi method was employed to achieve optimal DWR of weld bead and investigate the welding parameters that significantly affect welding quality. The experimental procedure of GTA welding with activating flux via the Taguchi method produced full penetration of weld bead on a 6.35 mm thickness of 6061 aluminum alloy plate with single pass weld.

Abstract: This paper applies an integrated approach using the Taguchi method, neural network (NN) and genetic algorithm (GA) to optimize the tensile-shear strength of resistance spot welding (RSW) specimens in automotive industry. The proposed approach consists of two stages. First stage executes initial optimization via Taguchi method to construct a database for the NN. In second stage, a NN with Levenberg-Marquardt back-propagation (LMBP) algorithm is used to provide the nonlinear relationship between factors and the response. Then, a GA is applied to obtain the optimal factor settings. The experimental results showed that the tensile-shear strength of the optimal welding parameter via the proposed approach is better than apply Taguchi method only.

Abstract: In order to achieve single pass welds without edge preparation, instead of multipass procedures, one of the most notable techniques is to use activating flux with GTA welding (GTAWflux) process. In autogenous GTA welding mixed fluxes (oxide SiO2 and Cr2O3), were applied on the weld area of type 310 stainless steel through a layer of the flux to produce a bead-on-plate weld. Many parameters affect the GTAW-flux process quality. The Taguchi method can improve on the disadvantages of full factorial design. However, in practice, it has certain limitations. In this work, a Taguchi-Neural approach (Combine Taguchi method and a neural network) was used to select the GTAW-flux process parameters. The experimental procedure of GTAW-flux process, via the proposed approach produced full penetration of the weld root in 8 mm thick type 310 stainless steel with single pass welds.