Accession Number : ADA119185

Title :   Elevated Temperature Low Cycle Fatigue of Nickel Base Superalloys in the Conventionally Cast, Directionally Solidified and Single Crystal Forms.

Descriptive Note : Interim rept. 1 Jun-31 Dec 81,


Personal Author(s) : Antolovich,Stephen D

PDF Url : ADA119185

Report Date : Mar 1982

Pagination or Media Count : 33

Abstract : High temperature low cycle fatigue (LCF) has been studied for directionally solidified (DS) and conventionally cast (CC) Rene 80. It was found that the LCF behavior of the DS material is in reason-able accord with an approach developed previously by the author in which the life is determined by a trade-off between environmental degradation and beneficial structural coarsening. The LCF life depends on the location in the ingot (top, middle or bottom) as well as on the orientation (Longitudinal, transverse, 45 deg). The location dependence can be explained in terms of the tendency to form a script-like carbide morphology, which is most pronounced in the middle, and a modulus effect. The modulus in the middle was intermediate between the bottom (high) and top (low) and for a plastic-strain controlled LCF test led to a rather large elastic strain component. The combination of high total strain range and deleterious carbide morphology reduced the fatigue life. By similar reasoning, the life was a maximum near the bottom even though the misorientation was greatest in this region. For the CC Rene' 80 it was shown that the best data correlation was obtained by using total strain range for tests carried out at 75 F. This reporesentation is consistent with the carbide-induced crack formation which was observed metallographically. (Author)

Descriptors :   *Superalloys, *Nickel alloy inconel, *Fatigue(Mechanics), High temperature, Microstructure, Single crystals, Solidification, Modulus of elasticity, Strain(Mechanics), Degradation, Casting, Carbides, Morphology, Fatigue life, Scanning, Electron microscopy, Interactions, Dislocations

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE