Abstract
Alloy 617 is currently considered as a leading candidate material for high temperature components in the Gen IV Nuclear Reactor Systems. Because of the unprecedented severe working conditions beyond its commercial service experience required by the Gen IV systems, the alloy faces various
challenges in both mechanical and metallurgical properties. This paper, as Part I of the discussion, is focused on the challenges and issues in the mechanical properties of Alloy 617 for the intended nuclear application. Considerations are given in details in its mechanical property data scatter, low creep strength in the desired high temperature range, lack of longterm
creep curves, high loading rate dependency, and preponderant tertiary creep. Some research and development activities are suggested with discussions on their viability to satisfy the Gen IV Nuclear Reactor System needs in near future and in the long run.
