Fatigue Property Enhancement of .ALPHA.-.BETA. Titanium Alloys by Blended Elemental P/M Approach.

Abstract

Attempts were madeto produce fatigue tolerant c(-p titanium alloys by the blended elemental (BE) P/M method using extra low chlorine (ELCL) titanium powder. The study was conducted in two stages. In the first stage, the effect of microstructural modification on the high cycle fatigue strength of ELCL BE Ti-6A1 -4V was investigated. Several different microstructural conditions were generated through combinations of processing and heat treatment and these were fatigue tested to find out the optimum microstructure. In a later stage, various kinds of ELCL BE ce-p titanium alloys were produced by both conventional and microstructure-controllable new BE methods with emphasis on relating composition/processing/micro- structure to fatigue properties. The precision sectioning methodwhich enables the concurrent observation of the initiation facets and the underlying microstructure was utilized to analyze fatigue crack initiation mechanisms.