圧延H形鋼のフラッシュ溶接で生じる残留応力とその特徴

抄録

Objecting to the rolled H section steel joined by using a newly developed flash welding system, a temperature of a specimen at joining was measured. Moreover, residual stress generated in the specimen was also measured. On the other hand, flash welding on the rolled H section steel was simulated by three-dimensional thermal elastic-plastic analysis based on FEM. The obtained results are as follows.
In the developed flash welding system, joints are heated by an electric current from the electrodes attached on the flange. From the results of temperature measurement, the same magnitude of heat input per unit volume could be recognized in the web and the flange. From the results of the non-steady heat conduction analysis for the developed model, a temperature history of the specimen joined by the flash welding could be simulated with a good accuracy. Residual stress obtained by the thermal elastic-plastic analysis agreed accurately with the measured one. From this, it was elucidated that residual stress generated by flash welding on the rolled H section steel could be obtained with a high accuracy by the analysis. In welds, σ_x of the flange and σ_z of the web were large tensile respectively. That is, the stress components in the direction of welding line became large tensile like as in arc welding. σ_y became compressive at the edge of the flange and became tensile at the center of the flange and at the web. It was elucidated that a stress resultant of σ_y is in a state of equilibration at the whole of the cross section. It was elucidated that an influence of generation of heat by arc at the weld interface was larger than that by a resistance on the generation of residual stress.