An Investigation of Elevated Temperature Fatigue Crack Initiation in 2 and 1/4 CR-1 MO Low Alloy Steel.
Abstract
Environmental effects in elevated temperature fatigue have been extensively studied and reported in the literature for 2 1/4 Cr-1 Mo steel. The results of cycles to failure (lumped initiation and propagation life) verses strain range have shown drastic reductions in fatigue life with a dwell period at compressive strains in each loading cycle. This thesis has separately examined the crack initiation and propagation stages for several specimens tested in air at 538 deg C without dwell and a single specimen with a five minute compressive dwell. With dwell, the crack initiation stage was severely reduced (by a factor greater than eleven) relative to testing without dwell. The results clearly indicate that oxide cracking is a precursor to crack initiation in the substrate. It is concluded that the fatigue life of this alloy must be estimated based on the crack propagation characteristics alone, since crack initiation can be expected very clearly (i.e., first few cycles) for any practical environment. Originator supplied keywords include: Fatigue, oxide cracking, 2 1/4 Cr - Mo Steel.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1984
- Accession Number
- ADA150670
Entities
People
- O. P. Keifer
Organizations
- Naval Postgraduate School