EFFECT OF NITROGEN IN SOLUTION ON HIGH-TE MPERATURE CREEP RESISTANCE OF HIGH-PURITY CHROMIUM

The effect of solute nitrogen on the high temperature creep resistance of pure chromium has been investigated in argon atmosphere using the specimens aged for 3.6 X 10(5)s at 1273K (200ppm Nitrogen) and as solu tion treated (without nitrogen). The minimum creep rate of the prior-a ged specimen was lower than that of the as solution treated one. The e volution of subgrains during creep was suppressed in the prior-aged sp ecimen compared with the as solution treated one. Stress reduction tes ts were conducted at the minimum creep rate, in order to evaluate the creep rates under the same subgrain size. Under the same subgrain size , the creep rate of the prior-aged specimen was 1/5 of the as solution treated one. The higher creep resistance of the prior-aged specimen w as attributed to the solid solution strengthening due to nitrogen.