Abstract

Annealing heat-treatment experiments at temperatures in the range of 1050 to 1150°C (1323 to 1423K) for durations in the range of 20 min to 22 h were conducted for HAYNESÒ718 superalloy plate. Grain sizes for the as-received and the annealed samples of the superalloy were measured by application of quantitative metallographic techniques. The grain-growth exponents, n, for the kinetic relationship (dD/dt = ktⁿ) were then computed, and the n values were found to lie in the range of 0.067 to 0.183. The microstructures of the as-received and annealed samples were critically compared for applications of the superalloy at high temperatures.

Key words: Superalloy, grain growth, kinetics, microstructure, gas-turbines.