Weld defects such like blow holes, porosities, etc. are not likely to become high stress raisers compared with planar defects like incomplete fusion. But, if their size and number are very large, fatigue strength becomes lower. Radiographic test has often been used to assure the integrity of welded joints. However, grade of defects classified by JIS Code does not have sufficient correlation with actual fracture strength.
Then, both radiographic tests and fatigue tests were carried out for A 5083-0 aluminum butt welded joints with porosities. The correlation between JIS Code and defect rate in X-ray photograph, and the correlation between defect rate in X-ray photograph and defect-area rate in fracture surface were made clearer. In addition, allowable defect-area rates in fracture surface and their corresponding JIS grade of defects were determined for respective surface treatment of butt welded joints.
