An Evaluation of Direct Aging to Achieve Optimum Mechanical Properties for the Metastable Beta Ti-8Mo-8V-2Fe-3Al Alloy
Metastable beta titanium alloys are usually given a conventional solution treating and aging heat treatment to achieve high strength. This has been the case for the alloy Ti-8Mo-8V-2Fe-3Al. The present paper examines an alternate heat treatment for Ti-8823, that of direct aging after fabrication. Material for this study was fabricated by extrusion processes that provide reduction of a) 30%; and b) 83–84% during hot working for which two different heat treatments are considered: a conventional solution treatment and age, and a direct age. The extrusion temperature was also varied for the material that had undergone the larger amount of reduction. Static tension, torsion, and fracture toughness properties are determined for various through-the-thickness locations. Also reported are crack growth data and uniaxial S-N fatigue curves obtained from tests run at an R ratio of 0.1. The information from these tests enables a comparison between the solution treated and aged, and the direct aged conditions for the larger amount of reduction. Except for the crack growth behavior these data are compared to that obtained from material that has received 30% reduction during hot working.
KeywordsFracture Toughness Fatigue Strength Crack Propagation Rate Compact Tension Specimen Extrusion Temperature
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