Method for improving fatigue properties of titanium alloy articles
AssigneeUnited Technologies Corporation
InventorsRobert Jacobi Henricks, Duane Louis Ruckle, Raymond Bender Slack
Life of this patent
Estimating the term…
Abstract
A thermomechanical treatment to improve the fatigue strength of articles made from one of a class of alpha beta titanium alloys. The treatment involves heating the alloy into the beta field, hot deforming the alloy at a temperature within the beta field, rapidly quenching the alloy to room temperature to produce a hexagonal martensite structure and then tempering at an intermediate temperature so as to produce a structure in which discrete equiaxed beta phase particles are presented in an acicular alpha matrix. This structure is particularly resistant to the initiation and propagation of fatigue cracks.
Claims3
A thermomechanical process to improve the fatigue properties of titanium alloys of the class which contain both alpha and beta stabilizers and contain from about 5 to about 20 volume percent of the beta phase under equilibrium conditions at room temperature, including the steps of:
- a. providing the alloy;
- b. heating the alloy to a temperature above the beta transus for a period of time sufficient to produce a structure which is substantially all beta;
- c. hot deforming the alloy at a temperature above the beta transus, an amount sufficient to refine the beta grain size;
- d. rapidly quenching the alloy to produce an acicular martensitic structure;
- e. tempering the martensite by reheating to an elevated temperature below the beta transus for a period of time sufficient to partially convert the martensite to acicular alpha, while permitting the formation of discrete equiaxed beta particles.
Dependencies are inferred from the claim text.