Analysis of Super Duplex Stainless Steel Properties as an Austenite-Ferrite Composite


Super duplex stainless steel (SDSS) is considered as a composite formed from a microstructure of an approximately equal mixture of two primary constituents (γ-austenite and α-ferrite phases) and the secondary precipitates (sigma, chi, alpha-prime, etc.). While the formation of these phases affects the properties of SDSS, however there are no rules that govern the relationship. In this work, the relationship between toughness as well as corrosion behavior of SDSS (UNS 32760) and the microstructure constituents has been experimentally investigated, and analyzed in view of the composite principles. Another two stainless steels namely; fully austenitic SASS (UNS N08367) and fully ferritic FSS (UNS S42900) are considered to simulate the constituent’s primary components in the composite which are austenite γ and ferrite α phases respectively. Samples of the composite and constituent’s steels are first subjected to solution annealing, where the composite steel has a microstructure of γ austenite and α ferrite grains. They were then subjected to similar different isothermal heat treatment cycles, for the formation of secondary phase precipitations within the transformation temperature ranges of each of γ and α primary grains. Impact toughness and corrosion (specific weight loss) tests were conducted on the annealed and isothermally treated samples. The composite rule of the mixtures (ROM) is used to analyze the relationship between the toughness and corrosion properties in the composite SDSS and the SASS and FSS constituent’s steels. The analysis indicates that in case of toughness, ROM applies well on the composite and constituents’ steels in the solution annealed and in isothermal treatment conditions, where better matching between experimental and calculated results is observed. When applying ROM for corrosion weight loss, a great difference is found between the experimental and calculated results, which is much reduced for solution treated samples ferritic and austenitic temperature ranges of 480℃ - 500℃ and 700℃ - 750℃ as for ferrite and austenite respectively.

Share and Cite:

Elsabbagh, F. , El-Sabbagh, A. , Hamouda, R. and Taha, M. (2015) Analysis of Super Duplex Stainless Steel Properties as an Austenite-Ferrite Composite. Materials Sciences and Applications, 6, 1121-1136. doi: 10.4236/msa.2015.612111.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Davis, J.R. (1994) ASM Speciality Handbook Stainless Steels, ASM International.
[2] ASTM A240 (2004) Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip for Pressure Vessels and for General Applications.
[3] ASTM A276 (2004) Standard Specification for Stainless Steel Bars and Shapes.
[4] ASTM A564 (2004) Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes.
[5] Kato, Y., Ito, M., Kato, Y. and Furukimi, O. (2010) Effect of Si on Precipitation Behaviour of Nb-Laves Phase and Amount of Nb in Solid Solution at Elevated Temperature in High Purity 17%Cr - 0.5%Nb Steels. Materials Transactions, 51, 1531-1535.
[6] Leffler, B. (2013) Stainless Steels and their Properties.
[7] Lo, K.H., Shek, C.H. and Lai, J.K.L. (2009) Recent Developments in Stainless Steels. Materials Science and Engineering R, 65, 39-104.
[8] Fontes, T.F. and R.M. (2011) Corrosion versus Mechanical Tests for Indirect Detection of Alpha Prime Phase in UNS S32520 Super Duplex Stainless Steel. Corrosion, 67, 1-7.
[9] Vitek, J.M., David, S.A., Alexander, D.J., Keiser, J.R. and Nanstad, R.K. (1991) Low Temperature Aging Behavior of Type 308 Stainless Steel Weld Metal. Acta Metallurgica et Materialia, 39, 503-516.
[10] Grobner, P.J. (1973) The 885 f (475℃) Embrittlement of Ferritic Stainless Steels. Metallurgical Transactions, 4, 251-260.
[11] Hattestrand, M., Larsson, P., Chai, G., Nilsson, J.-O. and Odqvist, J. (2009) Study of Decomposition of Ferrite in a Duplex Stainless Steel Cold Worked and Aged at 450℃-500℃. Materials Science and Engineering: A, 499, 489-492.
[12] Abdullah, M.A. (2009) Structural Characterisation, Residual Stress Determination and Degree of Sensitisation of Duplex Stainless Steel Welds. Ph.D. Thesis, RMIT University, Melbourne.
[13] Hsieh, C.-C. and Wu, W. (2011) Overview of Intermetallic Sigma (σ) Phase Precipitation in Stainless Steels. Taichung, Taiwan: International Scholarly Research Network ISRN Metallurgy, 2012, 16 p.
[14] Nilsson, J.-O. and Chai, G. (1997) The Physical Metallurgy of Duplex Stainless Steels. Sandvik Materials Technology, R&D Centre, Sandviken.
[15] Chumbley, L.S. (2005) Final Report on Clean Cast Steel Technology: Determination of Transformation Diagrams for Duplex Stainless Steel. Iowa State University, Ames.
[16] Francis, R. (2008) Zeron 100 Super Duplex Stainless Steel in Mining Industry.
[17] Thames Stock.
[18] ATI Allegheny Ludlum (2010) ATI-AL6XN Alloy (UNS N08367).
[19] Elsabbagh, F.M., Hamouda, R.M. and Taha, M.A. (2014) On Microstructure and Microhardness of Isothermally Aged UNS S32760 and the Effect on Toughness and Corrosion Behavior. Journal of Materials Engineering and Performance, 23, 275-284.
[20] ASTM A182 (2013) Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High Temperature Service.
[21] ASTM G48 (2011) Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution.

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.