Fracture toughness (KIC) is the one of the most important parameters for evaluating the fracture resistance of the machine elements or structural parts subjected to cyclic loading. These cyclic stresses can cause damage or premature failure. For these reasons, prior knowledge of the fracture toughness is critical. Some institutions have proposed the standards for determination of fracture toughness values. But these procedures of the standards are difficult to manufacture the specimens and cost a high price in terms of instrumentation. The objective of this work is determining fracture toughness with alternative methods which uses round bar specimens with and without fatigue precracking. In this way, fracture toughness can be evaluated rapid and inexpensive test methods. Two different approaches are investigated for S355 and Domex 700MC in experimentally. The values can be comparable with the values reported in the literature which are obtained by standard test specimens.Keywords: Fracture toughness, notched round bar, circumferentially cracked round bar
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