Residual Stress Effects at a Notch Root in A723 Steel to Extend Fatigue Life.
Abstract
Fatigue life tests were performed with notched bend specimens of ASTM A723 steel with three types of residual stress treatments and resulting residual stress: shot peening, bole swaging, and tensile overload. The three treatments produced widely different depths and surface values of residual stress near the notch root and different fatigue lives depending mainly on the notch root surface value of compressive residual stress. The highest life was measured from overload specimens which had both the deepest and the highest surface value residual stress distribution. Fracture mechanics-based calculations of fatigue life agreed well with measurements. The calculations accounted for the following factors that affect fatigue life: the crack growth properties of the material; the shallow surface-crack configuration; the applied loading; and the depth and surface magnitude of the residual stress distribution. A consistent description of fatigue life was obtained from a a delta K calculated life plot, where the delta K is for a shallow crack near the notch root and in the region of compressive residual stress. A power law relationship between delta K and fatigue life agreed well with the results from both the untreated notches and those with the three types of residual stress, indicating that fatigue life predictions could be made with some confidence for tests under generally similar conditions. jg
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1995
- Accession Number
- ADA294420
Entities
People
- John H. Underwood
Organizations
- United States Army Armament Research, Development and Engineering Center