Experimental and numerical investigation of initial notch radius effect on Charpy fracture energy in API X65 steel

Different factors such as initial notch angle, notch depth, notch root radius, notch, specimen size, hammer geometry and striker velocity, and initial notch creation method (i.e. broaching and machining) influence the experimental determination of Charpy impact energy. Thus, the study of the influence of these parameters on Charpy fracture energy is important. In the present research, Charpy impact experiments are conducted on test specimens made from API X65 steel (used for gas transportation pipelines). The tests samples have standard size with different notch radius (within the range of 0.13 - 0.41 mm). By measurement of fracture energy, Charpy impact energy is determined as a function of variations of initial crack radius. Through having geometrical dimensions of the initial notch and considering the stated standard tolerance the aforementioned function allows the determination of measurement error of API X65 steel Charpy impact energy. Then, the test samples are modeled as 3D in ABAQUS using Gurson damage theory. The comparison of test and simulation results for different notch radius are presented in details and compared.