Prediction of creep rupture life of a V-notched bar in DD6 Ni-based single crystal superalloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 615; pp. 14 - 21
• Main Authors: Liu, D.S., Zhang, D.X., Liang, J.W., Wen, Z.X., Yue, Z.F.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 06-10-2014; Elsevier
• Subjects: Applied sciences; Continuum damage mechanics; Creep; Creep (materials); Creep life; Cross-disciplinary physics: materials science; rheology; Damage; Deformation, plasticity, and creep; Exact sciences and technology; Finite element method; Fracture mechanics; Fractures; Materials science; Mathematical analysis; Mathematical models; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Multi-axial stress; Ni-based single crystal superalloy; Nickel; Nickel base alloys; Physics; Rupture; Superalloys; Treatment of materials and its effects on microstructure and properties; Creep life; Continuum damage mechanics; Ni-based single crystal superalloy; Multi-axial stress; Nickel base alloys; Notched test piece; Creep; Creep test; Fracture; Multiaxial load; Single crystal; Finite element method; Superalloy; Experimental result; Creep fracture; Stress distribution; Morphology; Continuum mechanics; Microstructure; Damaging
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.07.006

The circumferential V-type notched round bar has been designed to investigate the effect of multi-axial stress state on creep rupture behavior of DD6 Ni-based single crystal superalloys at 1100°C. Creep test on both smooth and notched specimens were carried out under 160MPa and 200MPa on the minimum net-section. Time to creep fracture was found to be higher in notched specimens than in smooth specimens. Finite element (FE) analysis coupled with continuum damage mechanics (CDM) was carried out to understand the stress distribution and the creep damage evolution under uniaxial and multi-axial stress states. The creep rupture life of the smooth specimen was successfully predicted by the classical Kachanov–Rabotnov damage law. The creep rupture life of the notched specimen predicted by finite element calculation incorporating a multi-axial creep CDM model was in good agreement with the experimental results. Both the fracture morphology and FE damage analysis indicate that rupture initiates first at the notch root in the notched specimen and finally towards to the center location.