Identifying the Effect of 475°C Embrittlement on the Cyclic Stress-Strain Response of Duplex Stainless Steel by Means of the Change in the Yield Stress Distribution

Abstract:

Duplex Stainless Steel is prone to the 475°C embrittlement, which leads to a change of the material properties. In this study the change in the cyclic stress-strain behavior was analyzed in room temperature fatigue tests in a condition without embrittlement and after annealing at 475°C for various times (different degrees of embrittlement), giving different degrees of pre-embrittlement. In the cyclic deformation curves a stronger softening with increasing degree of the embrittlement can be seen after an initial stage of cyclic hardening. In order to characterize the separation of the cyclic plastic deformation between the ferritic and austenitic phase of Duplex Stainless Steel the yield stress distribution function of the statistical treatment of the Masing model was used. For an automatic calculation of these individual yield stress distribution functions suitable mathematical distributions were selected and applied. The development of the distributions with the degree of embrittlement and the number of loading cycles reflect the microstructural changes in both phases.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 458-463
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.458
• Online since: March 2014
• Authors: Ken Wackermann, Hans-Jürgen Christ*
• Keywords: 475°C Embrittlement, Duplex Stainless Steel, Low Cycle Fatigue, Masing Model, Yield Stress Distribution

References

[1] M. Pohl, A. Ibach, K. -H. Lange, Microstructure and properties of Super-Duplex Stainless Steel, Pract. Metallogr. Special Issue 22 (1991) 333-349.

DOI: 10.1515/pm-1991-280704

[2] J.K. Sahu, Effect of 475°C embrittlement on the fatigue behaviour of a duplex stainless steel, Dissertation, Universität Siegen (2008).

[3] K. -H. Park, J.C. LaSalle, L.H. Schwartz, The low cycle fatigue behavior of spinodal decomposed Fe-26Cr-1Mo alloys, Acta Metall. 33 (1985), 205-211.

DOI: 10.1016/0001-6160(85)90138-5

[4] S. Hereñu, M. Sennour, M. Balbi, I. Alvarez-Armas, A. Thorel, A.F. Armas, Influence of dislocation glide on the spinodal decomposition of fatigued duplex stainless steels, Mat. Sci. Eng. A-Struct. A528 (2011), 7636-7640.

DOI: 10.1016/j.msea.2011.06.070

[5] G. Masing, Zur Heyn'schen Theorie der Verfestigung der Metalle durch verborgene elastische Spannungen, Wiss. Veröff. aus dem Siemens-Konzern 3 (1923), 231-239.

DOI: 10.1007/978-3-642-99663-4_17

[6] H. -J. Christ, Wechselverformung von Metallen, Springer-Verlag, Berlin, (1991).

[7] T. Mayer, Characterisation and modelling of the microstructural and mechanical evolution of a steam turbine rotor steel, Dissertation, ETH Zürich (2012).

[8] J. Polák, F. Fardoun, S. Degallaix, Analysis of the hysteresis loop in stainless steels II. Austenitic-ferritic duplex steel and the effect of nitrogen, Mat. Sci. Eng. A-Struct. A297 (2001), 154-161.

DOI: 10.1016/s0921-5093(00)01252-1

[9] S. Hereñu, I. Alvarez-Armas, A. Armas, S. Degallaix, A. Condó, F. Lovey, Microstructural changes in a duplex stainless steel during low cycle fatigue, MP Materials Testing 51 (2009) 359-364.

DOI: 10.3139/120.110044