JMMCE  Vol.7 No.2 , June 2008
Characterization of the Weld Regions within Duplex Stainless Steels using Magnetic Force Microscopy
Standard metallography and optical microscopy are well established techniques for the characterization of duplex stainless steels (DSS), which consist of approximately 50% ferrite and 50% austenite. Recently, the use of atomic and magnetic force microscopies (AFM and MFM respectively) have been employed to differentiate between magnetic and non magnetic phases in materials. Such techniques would be valuable to identify different phases in duplex stainless steels, particularly the weld regions, and would thus compliment standard metallographic and optical microscopy techniques. In particular, AFM and MFM would be particularly valuable for identification of phases within the different weld regions (root, fill and cap). In the present study, Gas Tungsten Arc Welded (GTAW) DSS samples, as a function of heat input and weld configuration, were subject to standard metallographic practices (ferrite content determination, Vickers hardness measurements, Charpy impact studies and transverse tensile testing) in addition to MFM analysis. The metallographic tests revealed that the weld properties were acceptable in accordance with current industrial standards. The MFM results of the weld metal shows the formation of both a finer and coarse structure within the weld metal, which is dependent on the level of undercooling.

Cite this paper
B. Gideon, L. Ward and K. Short, "Characterization of the Weld Regions within Duplex Stainless Steels using Magnetic Force Microscopy," Journal of Minerals and Materials Characterization and Engineering, Vol. 7 No. 2, 2008, pp. 115-126. doi: 10.4236/jmmce.2008.72010.
[1]   D. Peckner, I.M. Bernstein, in: H.B. Crawford, B. Gatewood (Eds. ), Handbook of Stainless Steels, McGraw-Hill, Caledonia, 1977.

[2]   M.S. Andrade, J.M.R Vilela, A.C.C. Reis, J.A. Sluss, V.T.L. Buono, Acta Microsc. 5B (1996 ) 266.

[3]   B.R.A. Neves, M.S. Andrade, Appl. Phys. Lett. 74 (1999 ) 2090.

[4]   S. Takaya, T. Suzuki, Y. Matsumoto, K. Demachi and M. Uesaka, J. Nuclear Materials 327 (2004) 19-26

[5]   A. Dias and M.S. Andrade, Appplied Surface Science 161 (2000) 109-114

[6]   J. Wittborn, Nanoscale Studies of Functional Materials using Scanning Probe Microscopy, Doctoral Thesis. Royal Institute of Technology, Stockholm, Sweden, p. 10 (2000).

[7]   B. R. A. Neves and M. S. Andrade, Identification of two Patterns in Magnetic Force Microscopy of Shape Memory Alloys, Appl. Phys. Lett., 74, 2090 (1999).

[8]   R. Wiesendanger, Scanning Probe Microscopy and Spectroscopy — Methods and Applications, Cambridge Univ. Press, Cambridge, 1996.

[9]   ASTM E562, Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count

[10]   ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products

[11]   J.L. Hunter, J. Bechhoefer, J. Vac. Sci. Technol., B 12 (1994 ) 2251.

[12]   D. Sarid, in: M. Lapp, H. Stark (Eds. ), Scanning Force Microscopy, Oxford Univ. Press, New York, 1991.

[13]   C. Schonenberger, S.F. Alvarado, S.E. Lambert, I.L. Sanders, J. Appl. Phys. 67 (1990) 7278.

[14]   Gideon B, Ward L P and Biddle G, Metallurgical Characterisation of Duplex Stainless Steel and their Susceptibility to Intergranular Corrosion, Proc. European Corrosion Federation (EUROCORR 2006) Conference Maastricht, Netherlands, 24–28 Sep (2006) Session K, pp. 190-191

[15]   L. Karlsson: 'Intermetallic Phase Precipitation in Duplex Stainless Steels and Weld Metals: Metallurgy, Influence on Properties and Testing Aspects', Welding in the World, vol. 43, no. 5, 1999.

[16]   B.J. Ginn and T.G. Gooch: `Effect of Intermetallic Content on Pitting Resistance of Ferritic-Austenitic Stainless Steels', proc. conf. Stainless Steels'91 Science and market, Chia Laguna Sardinia, Italy, 1999, vol. 3, p. 81-89