| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a welded joint which is suitable for a steel structure, such as a steel bridge, requiring excellent fatigue characteristics and of which fatigue strength is improved by introducing compression residual stress without imparting deformation, which becomes a new stress concentration part, on a welded part. <P>SOLUTION: The steel welded joint includes an impact trace continuously formed along a welding bead on a steel material surface by hammer peening or an oscillation terminal of ultrasonic impact treatment. A tip end part of the oscillation terminal is a circular arc shape in which a top part of a perpendicular cross section in a movement direction has a curvature radius of 1-10 mm, or a shape in which a top part of a perpendicular cross section in the movement direction includes a straight line part of 0.1 mm or less and chamfered parts having a curvature radius of 0.1-2 mm on both ends of the straight line part, or a circular arc shape on a major axis side of an oval shape in which a top part of a perpendicular cross section in the movement direction is the oval shape with a minor axis of 1 mm or longer and the minor axis/the major axis≤2. The oscillation terminal has a width of 1-10 mm in the movement direction. The impact trace is formed in a region of 5 mm, preferably 0.5-5 mm, on a base material side from a weld toe part in a maximum depth of at least 0.03 mm and less than 0.50 mm. <P>COPYRIGHT: (C)2012,JPO&INPIT |
