Abstract
An investigation was made of the susceptibility to cracking of two commercial 350 grades of maraging steel. Tensile tests were carried out on samples of the steels at very slow strain rates, and the load at failure was used to assess the susceptibility of the steels to cracking in an environment of gaseous uranium hexafluoride and hydrogen fluoride at 70 C. Good resistance to cracking was observed in dry uranium hexafluoride gas but cracking occurred when hydrogen fluoride was present at partial pressures above about 1 kPa. The failure stress decreased with increasing pressure of hydrogen fluoride. Scanning electron microscopy revealed brittle fracture surfaces in all cases where failure occurred at low stress, while failures at high stress were usually ductile in appearance. In view of the susceptibility of these steels to hydrogen embrittlement, it is suggested that the mechanism of failure in the presence of HF was associated with reaction-produced hydrogen. Oxide coated samples prepared by air aging, did not have significantly better resistance to cracking than vacuum aged Samples in the UF6/HF environment.
Remotely Monitoring Uranium-Enrichment Plants with Detection of Gaseous Uranium Hexafluoride and HF Using Lidar
