Grain size and grain growth in an equiaxed alpha-beta titanium alloy

Abstract

Methods of revealing grain size in a two-phase α-β titanium alloy have been examined and observations on beta grain growth in the presence of alpha have been carried out. The technique proposed by Greenfield and Margolin¹ for revealing β matrix grain sizes has been shown not to produce grain growth. However, for grain sizes of about 10 µm the G.M. technique does not reveal all the grains because of the similarity in orientation in neighboring grains. These clusters of similarly oriented grains are shown to persist as grain growth takes place but the misorientation between grains within a cluster decreases. Both the beta grain growth and alpha particle coarsening follow the same time dependency from which it is shown that a linear relationship exists between α particle size and β grain size. It is proposed that α particles must dissolve from theβ grain edges for β grain growth to occur. The linear dependency between beta grain size,D _β, and alpha particle size,d _α, can be rationalized either on the basis of geometrical or surface tension considerations.