Non-destructive metallography & replica method for inspection connecting rod material and cracks detection

Testing of materials properties is usually a discipline for the quality assurance during manufacturing processes. In condition monitoring, certification or upgrading of existing plants and in failure analysis similar benefits from non-destructive testing of materials properties can be achieved. Another benefit from the Non-Destructive Metallography (NDM) is that the test can be made on-site. NDM is a well established and proven tool to help determine the integrity of generator and hydro turbine components during their life-cycle in power plant environments. On-site metallography of components makes it possible to evaluate the microstructure of materials. It allows microstructural analysis of large components that are difficult to move or not permitted to be destructively tested, enabling rapid evaluation of the material. Here are monitored the microstructural changes and crack detection in St 35 connecting rod steel after approximately 15 years in service. The paper includes a short description of the replica method as a technique for microstructural examination of components by using non-destructive testing method.