| Alloy 800H, a candidate structural material for heat-exchangers to be used in nuclear hydrogen generation, was investigated for its high-temperature tensile properties and corrosion behavior. The tensile properties evaluated at different temperatures indicate that Alloy 800H was capable of maintaining high strength up to 600°C followed by its reduction in yield strength and ultimate tensile strength beyond this temperature. Further, the ductility was reduced at some critical temperatures, possibly due to the dynamic strain aging effect. Alloy 800H did not exhibit cracking in acidic aqueous solutions, both under constant-load and self-loaded conditions. Slight reductions in the true failure stress, percent elongation, percent reduction in area, and time-to-failure were observed when tested under a slow-strain-rate condition. The critical potentials became more active with increasing temperature determined by an electrochemical technique. The effect of anodic applied potential was more pronounced on the cracking susceptibility. Dimpled microstructures, characteristic of ductile failure, with some intergranular cracks were observed in the tested specimens. Typical austenitic grains with annealing twins and precipitates were observed in the microstructure. |
