Effects of alloying elements on the mechanical properties and corrosion behaviors of 2205 duplex stainless steels

The effects of alloying elements on the microstructure, mechanical properties, and corrosion behaviors of duplex stainless steels (DSSs) have been investigated in this study. Experimental alloys were prepared by varying the concentrations of the constituent elements in DSSs. Hot ductility test, tens...

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Bibliographic Details
Published in:Journal of materials engineering and performance 2001-04, Vol.10 (2), p.231-241
Main Authors: LLOU, Horng-Yih, PAN, Yeong-Tsuen, HSIEH, Rong-Luan, TSAL, Wen-Ta
Format: Article
Language:English
Subjects:
Alloys
Applied sciences
Corrosion
Corrosion prevention
Corrosion resistance
Corrosion tests
Ductility
Exact sciences and technology
Mechanical properties
Metals. Metallurgy
Pitting (corrosion)
Stress corrosion cracking
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Summary:The effects of alloying elements on the microstructure, mechanical properties, and corrosion behaviors of duplex stainless steels (DSSs) have been investigated in this study. Experimental alloys were prepared by varying the concentrations of the constituent elements in DSSs. Hot ductility test, tensile test, charpy impact test, and corrosion test were performed to evaluate the properties of the experimental alloys. The results showed that the extent of edge cracking of DSSs increased with the increasing value of the crack sensitivity index (CSI). The higher the hot ductility index (HDI) was, the better the hot ductility of DSSs achieved. Austenite ( gamma ) stabilizer generally caused a decrease in the strength and an increase in the charpy impact absorbed energy of the stainless steel. On the contrary, ferrite ( alpha ) former exerted its beneficial effect on the strength but became detrimental to the toughness of DSSs. The presences of sulfur and boron also caused a decrease in the impact energy, but nitrogen and carbon hardly affected the toughness within the concentration range tested in this study. The value of pitting nucleation potential (E sub( )np of different nitrogen contents in 3.5 wt.% NaCl solution at room temperature was almost the same, but the value of pitting protection potential (E sub( )pp among these alloys was increased with increasing the content of nitrogen. The susceptibility to stress corrosion cracking (SCC) of DSSs was high when tested in boiling 45 wt.% MgCl sub(2) solution. On the other hand, the time to failure of the experimental steels in 40 wt.% CaCl sub(2) solution at 100 degree C was longer than that in MgCl sub(2) solution. Nitrogen could affect the SCC behavior of DSSs in CaCl sub(2) solution through the combinative effects by varying the pitting resistance and the slip step dissolution. An optimum nitrogen (N) content of 0.15 wt.% was found where the highest SCC resistance could be obtained. Although gamma phase exhibited better resistance to SCC, cracks were found to penetrate through alpha and gamma grains or to propagate along the alpha / gamma interface. As a result, a mixed transgranular plus intergranular mode of fracture surface was observed.
ISSN:1059-9495
1544-1024
DOI:10.1361/105994901770345268