溶接継手におけるひずみ集中と疲労強度

概要

論文の詳細を見る
Copper-electroplating method reveals the microscopic strain distribution in the heterogeneous structure of welded joints under repeated stress. By this method the effect of microscopic strain concentration on fatigue crack initiation has been studied. The localized strain concentration was observed in such a coarse microstructure as a fusion boundary or columnar structure in weld metal. It has been revealed at low stress level, that the strain concentrates at the fusion boundaries or columnar structure, and that the strain concentration factor in these regions is about 1.4,while the value of concentration decreases with an increasing stress level, and then in the whole structure, i.e., parent metal, heat affected zone and weld metal, there is observed the same amount of concentration. Fatigue cracks at the low stress level are observed at fusion boundary or weld metal. At high stress level, on the other hand, they initiate simultaneously in three parts. Then it can be established quantitatively that the fatigue crack initiation depends only upon the local shear strain concentration. To improve the fatigue strength of welded joints, it is very important to observe a successive deformation behaviour in the microstructures under fatigue. It may be considerd, therefore, that the electroplating method is a useful means for this purpose.
社団法人溶接学会の論文
1969-12-25