Material property evaluation and response simulation of the diffusion bonded materials of compact heat exchanger

To meet the increased energy demand efficiently and economically, significant research and development of the Next Generation Nuclear Plant's (NGNP's) high temperature components, such as compact heat exchanger (CHX), are underway. The CHXs have intricate geometry which provides high compactness and large surface area for heat transfer. These properties make CHX an attractive and economical option for NGNPs. The complex geometry of the CHX is fabricated through two step processes, first, high temperature alloy plates are photochemically etched to get the desired shape, size and dimensions of hot and cold fluid channels, followed by the plates to be stacked up and diffusion bonded. The diffusion bonding process changes the base material properties. A question that will be addressed is that if the diffusion bonded materials can be assumed as a homogeneous material for design and analysis of CHX. To answer this question, a set of tension and creep tests were conducted on diffusion bonded Alloy 800H specimens at room temperature, 650℃ and 760℃. In addition, a unified constitutive model of the Chaboche type is calibrated to simulate the material responses. These experimental and simulated responses will be presented. In addition, the creep, fatigue and creep-fatigue tests to be performed in this study will be presented and discussed.