Influence of Heat Input in Pulsed Current GTAW Process on Microstructure and Corrosion Resistance of Duplex Stainless Steel Welds

The high corrosion resistance of duplex stainless steel (DSS) is due to elements such as Cr, Mo and N, but also depends on the microstructure. The best general properties are obtained with approximately equal amounts of austenite and ferrite and the absence of third phases such as σ (sigma) and Cr2N. In the present work the effect of heat input variations on the microstructure and corrosion resistance of a DSS UNS S32760 in artificial sea water media were studied. The corrosion resistance in 3. 5% of NaCl solution was evaluated by potentiostatic polarization tests at room temperature. It is found that the presence of sigma phase and Cr2 N decreases the corrosion potential. The specimen with heat input of approximately 0. 95 kl/mm have the best corrosion characteristics, which is the result for the lack of deleterious phases such as sigma and Cr2 N and balanced ferrite-austenite proportion.

[1]  John C. Lippold,et al.  Welding Metallurgy and Weldability of Stainless Steels , 2005 .

[2]  J. Pardal,et al.  Characterization of microstructure, chemical composition, corrosion resistance and toughness of a multipass weld joint of superduplex stainless steel UNS S32750 , 2007 .

[3]  E. Symniotis.  Galvanic effects on the active dissolution of duplex stainless steels. , 1990 .

[4]  H. Ezuber,et al.  Effects of sigma phase precipitation on seawater pitting of duplex stainless steel , 2007 .

[5]  M. Pohl,et al.  Effect of intermetallic precipitations on the properties of duplex stainless steel , 2007 .

[6]  P. Szabó,et al.  Energy-dispersive spectroscopy and electron backscatter diffraction analysis of isothermally aged SAF 2507 type superduplex stainless steel , 2004 .

[7]  S. Seshadri,et al.  Effect of weld metal chemistry and heat input on the structure and properties of duplex stainless steel welds , 2003 .

[8]  R. Newman,et al.  Detection of deleterious phases in duplex stainless steel by weak galvanostatic polarization in alkaline solution , 2006 .

[9]  J. Pardal,et al.  Influence of microstructure on the corrosion resistance of the duplex stainless steel UNS S31803 , 2008 .

[10]  Zin-Hyoung Lee,et al.  The effect of nitrogen and heat treatment on the microstructure and tensile properties of 25Cr–7Ni–1.5Mo–3W–xN duplex stainless steel castings , 2001 .

[11]  J. Yang,et al.  Microstructural characterization of simulated heat affected zone in a nitrogen-containing 2205 duplex stainless steel , 2002 .

[12]  N. Murugan,et al.  Optimization of pulsed GTA welding process parameters for the welding of AISI 304L stainless steel sheets , 2009 .

[13]  J. Yang,et al.  The effect of high-temperature exposure on the microstructural stability and toughness property in a 2205 duplex stainless steel , 2002 .

[14]  J. Lippold,et al.  The relationship between chromium nitride and secondary austenite precipitation in duplex stainless steels , 2003 .

[15]  X. Y. Chen,et al.  Grain refinement of Cr25Ni5Mo1.5 duplex stainless steel by heat treatment , 2003 .

[16]  A. Saatchi,et al.  Optimization of the pulsed current gas tungsten arc welding (PCGTAW) parameters for corrosion resistance of super duplex stainless steel (UNS S32760) welds using the Taguchi method , 2011 .