• Corrosion Science and Technology
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• 제22권5호
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• pp.322-329
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• 2023

There are a variety of heat exchangers used in automobiles, such as shell and tube heat exchangers, double tube heat exchangers, and plate heat exchangers. Most of them are water-cooled to prevent engine overheating. There have been reports of corrosion damage to these heat exchangers due to continuous wetting caused by external temperature differences, road pollutants, and snow removal. In addition, galvanic corrosion, which occurs when two dissimilar materials come into contact, has been identified as a major cause. In this study, corrosion characteristics and galvanic corrosion behavior of Al alloy (AA3003, AA4045 and AA7072) used in automobile heat exchangers were analyzed. Effective clad materials for heat exchanger tubes and fins were also evaluated. It was found that AA7072 should be applied as the cladding material for fin AA3003 and that AA4045 was suitable as a cladding material for tube AA3003 because this clad materials application was the most effective clad design to delay the occurrence of pinhole in the tube. Main factors influencing galvanic corrosion dissolution were found to be galvanic corrosion potential difference and galvanic corrosion current density.

• Journal of Welding and Joining
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• 제29권2호
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• pp.72-79
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• 2011

The scope of this investigation is to evaluate the effect of joining parameters on the microstructural features and mechanical properties of dissimilar aluminum alloys, 1mm-thickness fixing AA6K31 at the top position and fixing AA5J32 at the bottom position. The friction stir lap welds were studied under various welding conditions, rotation speed of 1000, 1250, 1500rpm and welding speed of 100, 300, 500, 700mm/min, respectively. Mechanical test has been investigated in terms of tensile shear test and hardness test. The results showed that three type nugget shapes such as onion ring, zigzag type, hooking with the void, have been observed with revolutionary pitch. All welding conditions fractured at the HAZ of top plate, A6K31 and also the strength compare with base metal of lap joints were low efficiency, 52~63%. The thickness of fractured position was decreased with the lower heat input conditions. The relationships were excellent due to linear between the effective thickness of fractured position and peak load. The fractured position was the interface between joint area and not joint area. Also the strength efficiency compared with base metal was lower than decreasing rate of thickness because the hardness was decreased at fractured position due to softened material.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.257-270
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• 2013

The use of lightweight materials has been steadily increasing in the automotive industry, and presents new challenges to material joining. Among many joining processes, self-piercing riveting (SPR) is particularly promising for joining lightweight materials (such as aluminum alloys) and dissimilar materials (such as steel to Al, and metal to polymer). However, to establish a process window for optimal joint performance, it often requires a long trial-and-error testing of the SPR process. This is because current state of the art in numerical analysis still cannot effectively resolve the problems of severe material distortion and separation in the SPR simulation. This paper presents a coupled meshfree/finite element with a moving boundary algorithm to overcome these numerical difficulties. The simulation results are compared with physical measurements to demonstrate the effectiveness of the present method.