SOLUBILITY PRODUCT AND PRECIPITATION OF TAC IN FE-8CR-2W STEEL

The precipitation behavior of TaC in austenite was studied to improve mechanical properties of a reduced-activation steel, Type F-82H tan 8% Cr-2%W steel). The solubility product of TaC in austenite of Type F-82 H was determined as function of temperature and was 70% larger than th at of gamma-Fe. On metallurgical examination, the following was found: (1) The nucleation and growth of austenite grains and/or the reverse alpha --> gamma transformation accelerated the precipitation of fine p articles of TaC, and the fine precipitates suppressed the further grow th of the austenite grains. (2) When homogenizing at 1523 K previously , coarse austenitic grains were observed by heating at 1223-1323 K as compared with the grains after directly heating of the hot-rolled plat e, while the solubility product itself was roughly independent of the homogenizing treatment. (C) 1998 Elsevier Science B.V. All rights rese rved.