Performance of Waspaloy at elevated temperature for heat exchanger applications.

摘要

This investigation was focused on characterizing the high-temperature tensile behavior and corrosion susceptibility of the nickel-based alloy Waspaloy, which is a candidate structural material for heat exchangers in the nuclear hydrogen generation program. The tensile properties, evaluated at three different temperatures, indicate that both yield and ultimate tensile strength were gradually reduced with increasing temperatures. While no failures were observed in stress corrosion cracking (SCC) tests in an acidic solution under a constant-load, the true failure stress (sigmaf) was reduced to some extent under a slow-strain-rate condition using both smooth and notched specimens. The critical potentials, determined in a similar environment by a polarization method, became more active at elevated temperature. Cracking was enhanced both at anodic and cathodic applied potentials, showing reduced failure strain and sigmaf. Compared to the other two tested nickel-based alloys, Waspaloy showed the lowest corrosion rate. The fractographic evaluations of the primary fracture surface of the tested specimens revealed dimpled microstructures, indicating ductile failures.