1979 Volume 48 Issue 9 Pages 683-689
The existence of the unusual fracture path transition phenomenon in Charpy impact test specimen had been already found out on the electron beam (EB)-weld metals of constructional high strength steels in the previous report. Then in this report, the occurring possibility of such "fracture path transition phenomenon" and its mechanism were theoretically studied by means of the stress analysis in static load for the bending model of impact test specimen of EB-weld metal using finite element method (FEM). The stress analysis was performed on the bending model for HT50 and 80 weld metals of 12 and 40 KJ/cm weld heat inputs. The remarkable conclusions are as follows;
(1) As compared the distribution of plastic zone in the model specimen for EB-weld metal between 12 and 40KJ/cm weld heat inputs, the remarkable large extensions of the plastic zone were observed in the part of base metal near the fusion boundary (Bond) in case of the former model specimen. From this results it is presupposed that the fracture path of this impact test specimen has a chance to deviate into base metal side in case of the weld metal of low weld heat input.
(2) It was expected that the fracture path transition has a tendency to occur with a decrease of the bead width in the test specimen dB and with an increase of the hardness in the weld metal Hv, w as a result of the comparison for the variation of the plastic strain at the base metal near the fusion boundary (εp, B) and the center of weld metal (εp, w) from V-notch bottom in the model specimen between 12 and 40KJ/ cm EB-weld metals.