Creep Void Formation and Rupture Lifetime in Multiaxial Stress States

Abstract:

This paper discusses creep void formation and rupture lifetimes in multiaxial stress states for a SUS 304 stainless steel at elevated temperatures. Biaxial and triaxial tension creep tests were performed using a cruciform and a cubic specimen, respectively. These two types of the specimens were designed to achieve uniform equi-biaxial and equi-triaxial stress distributions by a finite element analysis in the gage parts. Void formation at grain boundaries was observed by intermitting biaxial creep tests and by interrupting triaxial creep tests. Creep rupture lifetimes were also obtained in biaxial and triaxial creep tests. Biaxial stresses increase the void formation but give a little influence on a creep rupture lifetime in the correlation with von Mises equivalent stress. Triaxial stresses also increase the void formation and drastically reduce a creep rupture lifetime in the correlation with von Mises equivalent stress. Evident void formation in an equi-triaxial stress condition demonstrates that von Mises equivalent stress is not a suitable measure to evaluate creep damage development in multiaxial stress states. A new equivalent stress is proposed to evaluate creep rupture lifetimes in biaxial and triaxial stress states.

• Periodical: Key Engineering Materials (Volume 795)
• Pages: 159-164
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.795.159
• Online since: March 2019
• Authors: Masao Sakane*, Hiroki Kobayashi, Ryohei Ohki, Takamoto Itoh
• Keywords: Creep, Creep Damage, High Temperature, Multiaxial Stress, Rupture Lifetime, Void Formation

References

[1] H. Kobayashi, R. Ohki, T. Itoh, M. Sakane, Multiaxial creep damage and lifetime evaluation under biaxial and triaxial stresses for type 304 stainless steel, Eng. Fract. Mech. 174 (2017) 30–43.

DOI: 10.1016/j.engfracmech.2017.01.001

[2] S. Zhang, T. Wakai, M. Sakane, Creep rupture life and damage evaluation under multiaxial stress state for Type 304 stainless steel, Mater. Sci. Eng. A. 510–511 (2009) 110–114.

DOI: 10.1016/j.msea.2008.04.113

[3] M. Sakane, T. Hosokawa, Biaxial and triaxial creep testing of Type 304 stainless steel at 923 K, in: IUTAM Symp. Creep Struct., Springer, Dordrecht, 2001: p.411–418.

DOI: 10.1007/978-94-015-9628-2_39

[4] H.-T. Yao, F.-Z. Xuan, Z. Wang, S.-T. Tu, A review of creep analysis and design under multi-axial stress states, Nucl. Eng. Des. 237 (2007) 1969–(1986).

DOI: 10.1016/j.nucengdes.2007.02.003

[5] M.E. Kassner, T.A. Hayes, Creep cavitation in metals, Int. J. Plast. 19 (2003) 1715–1748.