Abstract
In this study, we comparatively investigate the low cycle fatigue behavior of Alloy 617 (INCONEL 617) weldments by gas tungsten arc welding process at room temperature and 800 °C in the air to support the qualification in high temperature applications of the Next Generation-IV Nuclear Plant. Axial total-strain controlled tests have been performed with the magnitude of strain ranges with a constant strain ratio (Rε = −1). The results of fatigue tests consistently show lower fatigue life with an increase in total strain range and temperature at all testing conditions. The reduction in fatigue life may result from the higher cyclic plastic strain accumulation and the material ductility at high temperature conditions. A constitutive behavior of high temperature by some cyclic hardening was observed. The occurrence of serrated yielding in the cyclic stress response was also observed, suggesting the influence of dynamic strain aging during high temperature. We evaluated a well-known life prediction model through the Coffin-Manson relationship. The results are well matched with the experimental data. In addition, low cycle fatigue cracking occurred in the weld metal region and initiated transgranularly at the free surface.
Highlights
The very high temperature reactor (VHTR) is one of the most promising nuclear systems among the Generation-IV reactors to economically produce electricity and hydrogen
We can deduce that the higher plastic strain deformation and the material ductility of the 800 ̋ C testing conditions to have a major role in the shorter fatigue life
Weldments fabricated by gas tungsten arc welding (GTAW) process were conducted at room temperature and 800 °C in the air, with a total strain range of 0.6, 0.9, 1.2, and 1.5%
Summary
The very high temperature reactor (VHTR) is one of the most promising nuclear systems among the Generation-IV reactors to economically produce electricity and hydrogen. The VHTR major components include the reactor internals, reactor pressure vessel, piping, hot gas ducts (HGD), and intermediate heat exchangers (IHX). These components are required to have good mechanical properties, creep-fatigue resistance, and phase stability at high temperatures. Alloy 617 is the leading candidate material to prolong the design life of IHX and HGD of helium-cooled VHTR systems due to its creep-fatigue resistance at high temperatures [1,2,3]. The components have a projected plant design service life of 40–60 years operation and 3–8 MPa in He impurities. The Alloy 617 for the IHX and other components is expected to operate at room temperature, which is assumed as a start-up condition, and at temperatures between 800–950 ̋ C
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call