Abstract
In this paper the monotonic tensile tests and the low cycle plastic fatigue tests of T-type butt welded joints with incomplete root penetration at the both edges of the test plate were carried out. The deformation capacity and the low cycle fatigue characteristics were compared with the results of the tests with incomplete penetration at the center of the test plate which were reported in the previous paper. The conclusions are summerized as follows. (1) The reduction of area and the static fracture ductility of the both edged root defects are smaller than the centered defect. On the contrary, the uniform elongation of the both defects are nearly equal. (2) The exponent k_p and the constant C_p for Manson-Coffin's equation can be expressed as the functions of the static fracture ductility and those functions have the nearly value in spite of the difference of the location of the defects. (3) In the low cycle plastic fatigue tests those number of cycles to failure is less than about 50, the fatigue characteristics of the both edged root defects is inferior to the centered root defects. (4) The relation between the static fracture ductility and the uniform elongation depends on the tensile strength of the weld metal to the one of the base metal and the location of defects. However, as the correlation can be recognized, if the influence of the ratio of the tensile strength and the location of defects are investigated by testing in future, the fatigue characteristics may be able to be expressed by the uniform elongation. (5) The relation between the plastic strain amplitude and the average hysteresis energy per cycle to failure is linear in log-log plot. Employing the above relation and the relation between the plastic strain amplitude and the number of cycles to failure, the relation between the strain amplitude and the total hysteresis energies to failure are induced linear in log-log plot.
