To discuss cxperimentally the validity of simplified estimation method of fatigue strength of butt welded jolnts with angular distortion and/or mis-alignment, fatigue tests were carried out on notched specimens under axial repeated stress superposed by bending stress secondarily, on the base metal specimens with modified reinforcement and angular distortion, and on the butt welded joints with angular distortion and/or mis-alignment of which reinforcements have conditions of as welded, dressing or flushing. From these tests followings are concluded. (1) If dimensions of notch in specimen are constant for various tests conditions and representation of the fatigue strength is described in terms of summation of nominal axial and bending stress at the part of crack initiation, σ_<rtb>, the fatigue strength at given crack initiation life, Nc, is presented higher as the ratio of bending stress to axial one increases. (2)σ_<rtb>-Nc diagrams of butt welded joint with various amounts of angular distortion coinside with that of the joints without angular distorsion. (3) Effects of dressing or flushing with reinforcements on the fatigue strength of butt welded joints with various amounts of angular distortion are nearly the same as that of the joint without angular distortion.

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