Open Access Conference Proceedings

The residual lifetime assessment and the risk of a possible service components failure are critical issues in the safety and reliability analyses of industrial plants. The residual lifetime can be evaluated by the standard mechanical test techniques, such as the tensile test, uniaxial creep test, the Charpy or the fracture toughness test. Fracture mechanics in particular has attained high significance in establishing ultimate load limitations and assessing the integrity of a large number of engineering structures of multifarious types. Standard mechanical tests used to determine the fracture toughness involve extraction of large blocks of material and therefore are not applicable to in-service components.The development and in-service application of essentially non-destructive, miniature material sample removal systems (e. g. the surface sampling systems, such as Electric Discharge Sampling Equipment - EDSE) provided a practical incentive for development of small specimen test methods to evaluate material properties, e. g. fracture toughness. The EDSE can cut out small slices (‘boat sampling’) about 3 mm thick and approximately 20 mm wide x 25 mm long from thick-section components leaving behind cavities with round edges that usually do not require repair.In this study, two different methods will be used for fracture toughness determination: Small Punch Test and multiple-specimen method using sub-size Charpy specimens (3x4x27 mm). Both methods require very little experimental material and specimens can be made directly from the removed ‘boat sample’ by the EDSE. The applicability and reliability of both methods will be discussed.

Keywords: Small Punch test, facture toughness, Micro-Tensile test, Mini-Charpy test

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