Zr-Nb 합금의 상변태에 따른 미세조직과 집합조직의 변화

초록

The microstructure and crystallographic texture evolution of a Zr-Nb alloy were studied in terms of processing parameters. The Zr-based alloy was melted, cast into a button shape and then subject to forging, hot rolling in an α+β range and heat treatment, either stress relaxation annealing or recrystallization annealing. The latter heat treatment resulted in an equiaxed microstructure different from that of the commercial Zr-2.5%Nb alloy used for pressure tube material in heavy water reactor. The crystallographic texture resulting from the recrystallization annealing heat treatment, as quantified by the Kearns number, revealed a basal texture could be obtained by a modified heat treatment. This was attributed to the phase transformation characteristics from βto equilibrium α or martensitic α' during the heat treatment, as demonstrated previously in Zircaloy.