Comparison of the methods for determination of the beginning of slow growth

Methods for determining the beginning of the slow plastic crack grow during the fracture toughness test of the materials in the elastoplastic region are reported. Electrical potential and acoustic emission methods are the most widely used among the methods under consideration. They permit determining the begining of the slow crack growth on one sample, though the results obtained are not always reliable. The method of T-R-curve is considered to be the only advisable at present despite its disadvantage associated with the tests of a considerable number of samples