Some Critical Studies of Macroscopic and Microscopic Fracture Criteria for Steel

摘要

Research shows how plane strain values of the crack tip opening displacement, COD, can be determined on pre-cracked Charpy specimens loaded well beyond general yield. The measurements are then used to determine K sub Ic values that agree with 'valid' measurements on twelve inch thick specimens of A533 steel. The results of an experimental and analytic visioplasticity investigation is described which allows a determination to be made of the critical local strain required to initiate fracture at the tip of a sharp notch. The report also presents the results and analysis of a study to determine quantitative relations between K sub Ic (and K sub Id) and microscopic variables such as grain size for cleavage fracture that occurs at low temperatures. (Author)