Al-Mg 合金の溶接金属におけるリップルクリスタルの形成(<特集>抗抵スポット溶接部の品質保証とその将来)

概要

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The development of new crystals in weld metals was investigated. The welding was performed by following two methods. The first method was that bead-on-plate welding was performed on specimens. The specimens were obtained by arc-spot-welding a piece of Al-4.90% Mg alloy on 99.999% Al sheets. The other method was that butt-welding was performed on 99.999% Al and Al-Mg alloys. In these weld metals new crystals unlike stray crystals were observed to develop along a curve of puddle isotherm besides columnar crystals grown from fusion boundary. These crystals were named "ripple crystals". Hence, the ripple crystals were elliptical-shaped when the welding was performed at a low speed. Subgrains were also developed in the ripple crystals and were observed to grow in the direction of <100>. Moreover, the concentration of magnesium was observed near the grain boundaries of the ripple crystals. It would be concluded, therefore, that magnesium contributed mainly to the development of the ripple crystals.
1975-11-05