The Effect of As-Large-As (ALA) Grains on the High-Temperature Fatigue Life of Waspaloy
Abstract
Waspaloy is a nickel superalloy that, when processed, may contain as-large-as (ALA) grains in the outer surface of the billet. Many components were manufactured containing this ALA region. The common practice now is to remove the ALA-affected region; however, the effect of these ALA grains in Waspaloy has not directly been studied. To characterize the material and determine the effects of the ALA grains, tensile tests and fatigue tests were performed at 538 degrees C to emulate the operating conditions of Waspaloy aerospace components. Half of the specimens tested were ALA containing specimens and the other half of the specimens were from the mid radius of the billet and did not contain ALA grains. Replicas were taken of several of each group to track crack initiation and growth. The fracture surfaces were also examined in a scanning electron microscope (SEM) where stereo pair photographs were taken so the surface geography could be viewed in a program called MeX by creating digital elevation maps (DEM). The tensile tests revealed yield strength variability in the ALA material. The fatigue data showed three types of behavior in the ALA material and two types in the non-ALA material. Based on the average material in both groups, the ALA material had a shorter average life. The short life specimens in each group, however, had almost the same number of cycles to failure, implying that the ALA grains had no specific bearing on the minimum bound of specimen life.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2006
- Accession Number
- ADA466607
Entities
People
- Mandy L. Brogdon
Organizations
- University of Dayton