Optimization of selected parameters and procedures in small punch test methodology

Assessment of reactor pressure vessels and other industrial components structural materials properties is currently based on the principles of using standardized and long-term employed methods of mechanical properties testing (e.g. impact tests, tensile tests). For the assessment of the current state and degradation prediction of an operated component, implementation of structural materials tests is nonetheless very complicated in terms of the availability of the material volume required to realization of tests in accordance with current normative documentation requirements. Due to the problematic material sampling from the operated component without affecting its integrity, more and more attention is paid to the implementation of perspective methods of evaluation of mechanical properties in processes of industrial component safe operation evaluation. These methods are mainly based on a semi-destructive approach allowing direct sampling of small volumes of material from the operated component and subsequent determination of mechanical properties using miniaturized test specimens. One of the most widespread perspective methods is the small punch test (SPT) - method based on the controlled deformation of thin sheets. The subject of the paper is the optimization of selected small punch test parameters, preparation technology of testing specimens and determination of suitable geometry of experimental fixtures, that are used for experiments in the testing laboratories. Within the experimental program attention is especially paid to the comparison of receiving hole edge configuration - radius/chamfer edge. The aim of the paper is to solve several open questions in the current state of small punch testing methodology and to obtain a comprehensive basis for the implementation of resulting recommendations into the process of currently ongoing standardization within the normative organizations ASTM and EN. This is achieved through a program of experimental tests and computational analyses (FEM) on the IAEA correlation material A533B (JRQ).