SOFTENING OF CAST IRON BY IRRADIATION WITH NEUTRONS,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
Pagination or Media Count:
Groups of specimens of mallaeable cast iron, annealed for 34 hr at 970C, were exposed to integral fluxes of 10 to the 16th power, 10 to the 17th power, 10 to the 18th power, 10 to the 19th power, and 10 to the 20th power neutronssq. cm in a water-moderated water-cooled reactor. Before and after the irradiation the specimens were tested for linear wear W, friction coefficient mu and temperature t of the lubricant emerging from the friction zone. Vickers hardness, and microhardness. The wear tests showed that W, mu and t are hardly affected by irradiation. Hardness, as a yardstick of plastic deformation, is a characteristic of the wear resistance of materials. The pattern of variation in the hardness of the irradiated malleable and high-strength cast irons resembles the pattern of variation in their wear resistance. Thus hardness decreases following the irradiation of malleable cast iron with insignificant neutron fluxes 10 to the 17th power -10 to the 18th power neutronssq cm but increases again as the neutron dose is increased. A similar pattern of variation in microhardness is observed. Thus, irradiation is accompanied by two simultaneous processes softening of the material due to the weakening of grain boundaries and hardening of the crystal lattice in proportion to the number of the bombarding fast neutrons. As irradiation time increases, the hardening process begins to predominate.
- Metallurgy and Metallography
- Radioactivity, Radioactive Wastes and Fission Products