Abstract
The Haynes (R) 718 Ni-base superalloy has been investigated by use of modern material characterization, metallographic and heat treatment equipment. Grain growth annealing experiments at temperatures in the range of 1050-1200 degrees C (1323-1473K) for time durations in the range of 20 min-22h have been conducted. The kinetic equations and an Arrhenius-type equation have been applied to compute the grain-growth exponent n and the activation energy for grain growth, Q(g), for the investigated alloy. The grain growth exponent, n, was computed to be in the range of 0.066-0.206; and the n values have been critically discussed in relation to the literature. The activation energy for grain growth, Q(g), for the investigated alloy has been computed to be around 440 kJ/mol; and the Q(g) data for the investigated alloy has been compared with other metals and alloys and ceramics; and critically analyzed in relation to our results.