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http://dx.doi.org/10.20466/KPVP.2016.12.1.041

Effect of long-term thermal aging on the microstructural and mechanical characteristics of nickel-based alloy weldment  

Yoo, Seung Chang (울산과학기술원, 원자력과학 및 공학과)
Ham, Junhyuk (울산과학기술원, 원자력과학 및 공학과)
Kim, Ji Hyun (울산과학기술원, 원자력과학 및 공학과)
Publication Information
Transactions of the Korean Society of Pressure Vessels and Piping / v.12, no.1, 2016 , pp. 41-48 More about this Journal
Abstract
To investigate the effect of long-term thermal aging on the microstructural and mechanical characteristics of weldment made of nickel base alloy and its weld metal, an accelerated heat treatment was applied to simulate the process of long-term thermal aging in the operating condition of nuclear power plant. A representative nickel-based weldment with Alloy 600 and Alloy 182 was fabricated and heat-treated at $400^{\circ}C$ for 1,713 h and 3,427 h to simulate the thermal aging for the period equivalent to 15 and 30 years in operating pressurized water reactors, respectively. The microstructural and mechanical characteristics were analyzed by using optical microscopy, scanning electron microscopy and Vickers microhardness measurement. Changes were observed in precipitation behavior and microhardness of each specimen, and these changes were mainly attributed to the change in precipitated morphology and residual stress across the weld during the thermal aging process.
Keywords
Nickel-based alloy; Thermal aging; Fusion boundary; Chromium precipitate; Microhardness; Scanning electron microscope;
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