Microstructure characterisation and creep resistance of a candidate Ni-Cr-Mo corrosion resistant alloy for application in a molten salt

nuclear reactor

Sachin L. Shrestha1, Michael Drew1, Dhriti Bhattacharyya1, Elizabeth Budzakoska-Testone1, Roman Voskoboynikov1, and Warwick Payten1

1Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights NSW 2234 Australia

e: sachin.shrestha@ansto.gov.au

This study investigates the microstructure-property relationship of GH3535 Ni-Mo-Cr alloy during creep testing at temperatures of 700 and 750 oC. GH3535 alloy is a candidate structural material for future molten salt nuclear reactors at the Shanghai Institute of Applied Physics (SINAP). In order to assess its service properties, creep tests on the GH3535 alloy were conducted at stresses below 0.2% proof stress to be most relevant to the desired long term operating conditions. Time-temperature parametric relationships were used to compare the obtained results with published data. The microstructure of the samples has been examined by optical microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. The information obtained were used to determine phase instabilities, dislocation network, grain structure, and deformation/ rupture mechanisms and their relation to the alloy’s creep properties.

Figure 1. Local Misorientation map displaying the dislocation substructure of GH3535 alloy after creep rupture.