RELATIONSHIPS AMONG THERMOMECHANICAL TREATMENTS, MICROSTRUCTURE, AND TENSILE PROPERTIES OF A NEAR BETA-TITANIUM ALLOY - BETA-CEZ .1. RELATIONSHIPS BETWEEN THERMOMECHANICAL TREATMENTS AND MICROSTRUCTURE

The high strength medium temperature and beta metastable titanium allo y, beta-CEZ, is designed for use in the compressor of a jet engine. Th e purpose of this research was to investigate how the thermomechanical treatments (forging or solutioning conditions and quenching) influenc e the microstructure. A series of various heat-treating steps were con ducted in order to quantify the relationship between thermomechanical parameters and microstructural factors. The detailed characterization of microstructure was based on SEM observations of primary alpha plate lets with the aid of an Image Analysis system. A pronounced influence of thermomechanical treatments on microstructure was found. Several pa rameters characterizing the microstructure of alpha platelets such as the area fraction, length, width, perimeter, surface, density, and asp ect ratio, have been found to depend on the solutioning conditions. Fu rthermore, with the exception of the area fraction, these different mi crostructural parameters were found to be also governed by the forging conditions.