Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 13, 2020 - September 16, 2020
In the Ni-based superalloy Alloy 625, which has been developed for the next-generation high-efficiency thermal power plant, Nb carbides precipitate at grain boundaries during operation at elevated temperatures under high-load conditions. This growth of precipitates degrades the long-term reliability of the alloy, because the growth of creep voids are accelerated around it, and thus, grain boundary cracking is accelerated. Therefore, continuous monitoring of carbide precipitates near grain boundaries in the material used for pressure vessels, pipes, and turbine blade during operating is an essential issue to prevent accidental fracture. In this study, a new non-destructive detecting method of Nb-base precipitates in the atmosphere was proposed by measuring the spatial element distribution using the reflectance spectrum of visible lights. The growth of the precipitates was observed under creep loading at 750oC.
