Method for evaluating the crack resistance of small sized metallic materials

A method for evaluating the complex multiparameter crack resistance of metals under plane strain conditions and developed at the Strength of Materials Institute of the Ukranian Academy of Sciences has been approved. Joint and independent determination of failure parameters has been developed using test measurements on compact specimens containing face notches. These measurements include load, load displacement, crack opening at a distance of 2–3 mm from the tip, and length of the growing crack (using the unloading compliance method). This approach allows one to avoid testing samples having various sizes. It also estimates the reliability of the results through their mutual comparison. Tests were carried out on six typical materials used in the construction of reactors (pressure vessel steel, and zirconium and titanium alloys). This enables us to optimize the procedure used to determine the start values of the J1 integral, and the crack tip opening of compact samples having a thickness of 12 mm. The advantage of using the J1-R curve for this is confirmed.