Fatigue Crack Propagation in Ti Alloys.
Abstract
The influence of microstructure, slip behavior, and gaseous environment on the fatique crack propagation of Ti alloys has been investigated. Large grain or single crystal material has been used extensively in order to ensure that the crack-tip plasticity is smaller than the scale of the microstructure. As a result, extensive Stage I crack propagation occurs. The experimental relationships between crack-tip plasticity, orientation of the crack plane to the stress axis, fractography, and the resulting fatigue crack growth behavior is presented. Several Ti alloys are examined in lab air, dry helium, or hydrogen environments: beta-phase Ti-40V, metastable beta Ti-27V, and Ti-30V,alpha-phase Ti-4Al, and the alpha-beta alloy, Ti-8Al-1Mo-lV. The behavior of the beta Ti alloys can be analyzed primarily in terms of crack advance by an intersecting slip process resulting from flow on at least two active slip systems. In contrast, the mechanism for Stage I fatigue in alpha and alpha + beta Ti alloys appears to be dominated by basal slip and strongly influenced by environment. Aspects of the cyclic stress-strain behavior of beta and alpha + beta Ti alloys are also reported. In addition, strengthening of Ti alloys by eutectoid decomposition is briefly discussed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 25, 1978
- Accession Number
- ADA062771
Entities
People
- Donald A. Koss
Organizations
- Michigan Technological University