Modelling of anisotropic creep deformation and damage in single crystal superalloys

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00232-K· OSTI ID:105942

Li, S X; Smith, D J ^[1]

---

1. Univ. of Bristol (United Kingdom). Dept. of Mechanical Engineering

Previous studies on the creep behavior of single crystal nickel base superalloys reveal that both creep deformation behavior and stress rupture properties of single crystal alloys are strongly dependent on crystal orientation and temperature. A physical model of creep deformation in single crystal superalloys has been proposed by Ghosh et al. This model accounts for the anisotropy and asymmetry of creep by viscous glide on specific crystallographic slip systems and for the tertiary creep behavior through a damage parameter that is related to the accumulation of mobile dislocations in each slip system. The model has been applied to analyze the creep curves of the single crystal nickel base superalloy SRR99, with particular reference to [001] and [111] orientations. The model also attempts to predict the change in the anisotropy of creep behavior with stress and temperature, and the changes in the orientation and specimen cross-section with creep strain. The creep model proposed by Ghosh et al has been modified and extended to describe the anisotropic creep behavior of single crystal superalloys for multiaxial stress states. The equations must be used with a general transformation procedure to relate the crystallographic deformation to the global loading directions. Three creep rupture criteria based on material damage in single crystal superalloys have been suggested. The creep damage criterion that takes into account of the different effects of damage on octahedral and cubic slip system and includes interaction effects between the two types of slip provided the best predictions of creep rupture life for the single crystal nickel base superalloy SRR99.

• OSTI ID: 105942
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 5 Vol. 33; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CREEP
CRYSTAL LATTICES
DAMAGE
DISLOCATIONS
MATHEMATICAL MODELS
MICROSTRUCTURE
NICKEL BASE ALLOYS
ORIENTATION
SLIP
STRAINS
STRESSES
TEMPERATURE DEPENDENCE