大型溶接構造物の微小き裂進展と疲労寿命(<特集>高温強度)

概要

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To develop a method for evaluating the fatigue life of large structural components by using the data obtained with bar specimens 10 mm in diameter, a bending fatigue test was performed on a large butt-welded joint plate of a 50 mm thick hot-rolled SUS304 stainless steel made by hot-wire TIG welding. This test confirmed the evaluation method proposed and showed the followings. (1)The peak strain range in the welded metal becomes 1.8 times as large as the average strain range of welds because of the metallurgical discontinuity in the welded metal and the different deformation characteristics of the base and weld metals. As a result, fatigue cracks initiate where the peak strain occurs. (2)The most part of fatigue life of large structural components is crack propagation process, so that it is reasonable to evaluate fatigue life based on crack length. (3)Scale factors between the large structural component and the small bar specimens can be calculated using the fatigue failure probability of the small bar specimens, by taking the ratio of two test region areas into consideration. (4)If the crack initiation life corresponding to a surface crack length less than 2 mm is used, the life evaluation method based either on the base metal data or on the welded joint data obtained using small bar specimens is reasonable.
社団法人日本材料学会の論文
1995-01-15