Effect of Solidification Structures on Fatigue Characteristics of Weld Metal of A 5052 Al Alloy

概要

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Fatigue test was performed on a base metal and weld metals of A 5052-0 aluminum alloy each with soliaification structure of columnar crystals, feathery crystals or equiaxed dendrites. Investigations were made on the relation between the weld solidification structures and fatigue characteristics. The fatigue strengths of the weld metals were lower than the strength of the base metal. In the weld metals the strength of equiaxed dendrites was the highest. In the base metal, columnar crystals and equiaxed dendrites, anisotropy of the fatigue strength was not observed. In feathery crystals, however, the anisotropy was observed. The crack propagation rates in the weld metals were less fast than the rate in the base metal. In the weld metals the rate was the slowest in equiaxed dendrites and the fastest in columnar crystals. In the feathery crystals the rate was almost the same as that in columnar crystals when the growth direction of feathery crystals was parallel to the direction of propagation of fatigue cracks. When the growth direction of feathery crystals was normal to the direction of propagation of fatigue cracks, however, the rate decreased to that in equiaxed dendrites. Besides, it was made clear from the observation of the feature of fatigue crack propagation that the cracks propagated very easily along twin planes of feathery crystals.
社団法人溶接学会の論文
1980-04-01