Magneto-optical method to study the material for thermonuclear reactor first wall

Investigated is the formation of the ferromagnetic layer on the surface of chromium-manganese (EP-838) and chromium-nickel (SS-316) austenitic steels after annealing of samples in deep vacuum at the service temperature of the thermonuclear reactor wall (500 deg C) and at temperatures of 940 and 1100 deg C which may occur at spots where blistering occurs. The magnetic properties of the surface layer are studied by the magnetooptical method of investigation. A ferromagnetic α-phase is discovered in the EP-838 steel after its annealing at 50O deg C. The thickness of the ferromagnetic layer increases with the annealing temperature, this being related to a greater evaporation from the steel of volatile elements mainly, manganese. No ferromagnetic layer has been in the SS-316 steel. The effectiveness is noted of the magnetooptical method for investigating the condition of the surface layer of the first wall of thermonuclear reactors in service