Abstract
Tensile fracture test of notched bars produced from 800-MPa tensile strength steel plates subjected to heat cycles was done under quasi-static monotonic loading. Three series of heat cycles were applied to the plates, i.e., nine sets of heat treatment given in a temperature-controlled oven, actual welding heat input by submerged arc and by electroslag weldings, and simulated welding heat input. These various heat cycles changed the material properties in a wide soectrum. Two important facts were obtained: The strain at the onset of a ductile crack at the notch is proportional to the uniform strain capacity pertinent to the material therein. The plastic strain increment during the crack propagation preceding the final fracture is proportional to the Charpy impact value at the same temperature and also to the rupture strain of the material coupon test.
