抄録
It becomes clear that residual stress at boxing fillet weld toe at the end of stiffner can be turned to be compressive due to appropriate flame line heating and at a result, fatigue strength of the boxing fillet weld joint increases very much, in the previous paper. Moreover, the selection method for conditions of flame line heating which lead to maximum compressive residual stress at the boxing fillet weld toe is also introduced, such as the situation of heating, length of line heating, gas flow rate, travel speed of flame heating and torch hight. The above specimen does not have other stress concentrated part except the boxing fillet joint. However in case of a continuous fillet weld joint with load earring girder of which fatigue crack initiation part is usually at the fillet weld toe near the girder due to high stress concentration, large tensile residual stress generates at the fillet weld toe apart from the girder near flame line heating, even if compressive residual stress generates near the girder due to line heating. Therefore it is considered that fatigue initiation part moves to the part near line heating where stress concentration is smaller than the part near the girder. Then enhancing effect of fatigue strength may be decreased, which is studied experimentally in this paper.
