A Study to Improve Weld Strength of Al 6k21-T4 Alloy by using Laser Weaving Method

Kim, Byung-Hun; Kang, Nam-Hyun; Park, Yong-Ho; Ahn, Young-Nam; Kim, Cheol-Hee; Kim, Jung-Han

Journal of KWJS 2009;27(4):49-53.
Published online September 14, 2009.

레이저 위빙을 이용한 Al 6k21-T4 합금의 용접 강도 향상

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A Study to Improve Weld Strength of Al 6k21-T4 Alloy by using Laser Weaving Method

Byung-Hun Kim, Nam-Hyun Kang, Yong-Ho Park, Young-Nam Ahn, Cheol-Hee Kim, Jung-Han Kim

Abstract

For Al 6k21-T4 alloy, linear laser welding produced the lower shear-tensile strength than the base metal. This study improved the shear-tensile strength by using the weaving laser at the optimized welding condition, i.e., 2mm weaving width and 25Hz frequency. The large weaving width increased the weld width, therefore improving the joint strength. For the specimen of low strength, the porosity was distributed continuously along the intersection between the plates and fusion line. However, for the optimized welding condition, large oval-shaped porosities were located only in the advancing track of the concave part. Regardless of the welding condition, solidification cracking was initiated at the intersection and propagated through small porosities in the weld part. furthermore, the concave part had more significant porosity in the weld and HAZ, respectively than the convex part. The continuity of porosities played a key role to determine the strength. And, the weaving width was an important parameter to control the strength.

Key Words: 3~4 Weaving laser, Microstructure, Crack, Al 6k21-T4