A comparison of conventional mechanical testing techniques with innovative testing techniques for the evaluation of mechanical properties of NPP structural materials

The innovative testing methods of Small Punch (SP) and Automated Ball Indentation (ABI) tests are based on the determination of material properties from sub-sized samples. These methods are promising to evaluate the components of nuclear power plants since they preserve the structural integrity of the component. The SP test is a semi-destructive method that employs miniaturised plate-shaped samples of various geometries. The method is based on the penetration of a sample with a semi-spherical punch. The sample deflection is measured throughout the test. The ABI test is a fully automatic test based on multiple indentations at a single penetration location on a polished sample surface with a spherical indenter of various diameters. The purpose of the test is to determine the tensile properties of materials in a non-destructive and localised fashion. A comparison has been made between SP, ABI and conventional tensile tests on the measurement of yield strength for the A533B (JRQ) ferritic steel which is a base metal of the pressure vessels of western PWR. The results show an excellent correlation for both innovative methods and the conventional tensile tests