Crack Growth Behavior of Alloy in-100 under Sustained Load at 732 C (1350 F).
Abstract
Sustained load crack growth in IN-100 at 1350 F (732 C) is studied using two specimen geometries, a standard compact tension specimen and a radially cracked ring loaded in tension. The effects of specimen thickness on the growth rate are investigated covering a range from 0.22 inch (5.6mm) to 0.72 inch (18.3mm) in thickness. Only the thinnest specimens show a crack growth rate which is lower than that obtained from all of the other thickness specimens. Stress intensity factor, net section stress, load line displacement rate, and the C*-integral are investigated as possible crack growth rate correlating parameters. In addition, a crack driving force function, G, is developed for a linear elastic creeping solid which represents the excess of energy available for creating new crack surfaces. In particular, the crack growth rate is observed to decrease from an initially higher value to a 'steady state' rate which depends on the stress intensity factor, net section stress or load line displacement rate. In the correlation of the stress intensity factor, the magnitude of this initial growth rate is about double the 'steady state': creep crack growth rate. The concept of an effective crack length determined from specimen compliance measurements is introduced as a measure of crack length for severely tunneled crack front geometries. Neither net section stress, load line displacement rate nor C* are found to be acceptable as crack growth parameters based on data from both test geometries. Although the stress intensity factor, K, provides fair correlation, the phenomenology of creep crack growth prevents its description adequately with only a single parameter. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1981
- Accession Number
- ADA100642
Entities
People
- Robert C. Donath
Organizations
- Wright Laboratory