摘要
Power generating unit structures are designed and built to meet standard to secure its safety for expected life time.As the structures have been exposed to combined environment, degradation of structure material is accelerated and it can cause unexpected damage; ev-aluating precise mechanical properties of weak site is an essential research area as it is directly connected to safety issues.But most conventional tests of such properties cannot be performed on in-service power plants and oil-gas pipelines because of their destructive nature.Instrumented indentation testing (IIT), however, is simple to perform and does not require a sample of any specific shape or size: for testing, it is enough to polish the surface of the object to be tested.In addition, the locality of property measurement makes it easy to find weak points nondestructively.Here we introduce the theoretical model derived from the indentation curve to estimate mechanical properties and demonstrate that results from IIT show good agreement with those of conventional testing.We also describe the application of IIT for safety inspection and assessment.