Influence of precipitate morphology on the high temperature fatigue properties of SRR99

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(95)00113-A· OSTI ID:131498

Henderson, M B; Martin, J W ^[1]

---

1. Oxford Univ. (United Kingdom). Dept. of Materials

Fatigue crack growth (FCG) tests have been conducted in air at 650 C and 850 C on <001> oriented single crystals of SRR99 having the {gamma}{prime} particles in the form of: (A) 0.3 {micro}m cuboids; (B) 0.2 {micro}m ogdoadical cuboids; and (C) a coarse, rafted {gamma}{prime} structure. In general, reducing the frequency and increasing the temperature enhances crack-tip shielding at low {Delta}Ks due to increasing oxide induced crack closure. In material A at 650 C the crack path changes from one of {gamma}{prime} precipitate cutting on {l_brace}001{r_brace} to propagation within the matrix as {Delta}K increases. Enhanced crack branching at 850 C improves the Paris regime behavior compared with that seen at 650 C. In material B at 650 C, greater cross slip at lower frequency reduces slip reversibility, thus enhancing the fatigue crack growth rate (FCGR). At 850 C crack tip blunting and meandering, associated with {gamma}{prime} cutting, improves the high {Delta}K FCG response and on a strength/modulus normalized basis is comparable with that seen for material A. Material C shows a similar FCG resistance to A at 650 C, but there is an acceleration in FCGR at 850 C, which can be accounted for in terms of the lower proof stress and modulus of this microstructure.

• OSTI ID: 131498
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 11 Vol. 43; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
AGING
AIR
ALUMINIUM ALLOYS
CARBON ADDITIONS
CHROMIUM ALLOYS
COBALT ALLOYS
CRACK PROPAGATION
CRACKS
FATIGUE
MATERIALS
MICROSTRUCTURE
MORPHOLOGY
NICKEL BASE ALLOYS
PARTICULATES
SAMPLE PREPARATION
SLIP
STRESSES
TANTALUM ALLOYS
TEMPERATURE DEPENDENCE
TITANIUM ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN ALLOYS
TURBINE BLADES