Effect of Secondary Phases Precipitation on Corrosion Resistance of Duplex Stainless Steels

2016 ◽  
Vol 879 ◽  
pp. 1495-1500 ◽  
Author(s):  
Luca Pezzato ◽  
Mattia Lago ◽  
Katya Brunelli ◽  
Marco Breda ◽  
Enrico Piva ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Stainless Steels ◽  
Room Temperature ◽  
Volume Fraction ◽  
Secondary Phase ◽  
Duplex Stainless Steels ◽  
Secondary Phases ◽  
Critical Range ◽  
Pitting Corrosion Resistance ◽  
Equivalent Number

Duplex Stainless steels (DSS) are biphasic austeno-ferritic steels in which the best combination of mechanical and corrosion resistance properties is achieved for almost equal volume fraction of the phases. These steels are classified according to their pitting corrosion resistance, assessed by the PREN index (Pitting Resistance Equivalent Number) which, although qualitatively, is widely employed as comparison. The present work is aimed to study the pitting resistance of four DSS grades (SAF 2101, 2304, 2205 and 2507) in the as-received condition and after isothermal aging in the critical range 750°C-900°C, to highlight the effect of secondary phases precipitation on the corrosion behavior. The materials were potentiodynamically tested in artificial seawater (pH7) at room temperature and the corresponding Critical Pitting Temperatures (CPT) were determined according to ASTM G150. Secondary phase precipitation mainly affected the lean duplex grades whereas the high-alloyed DSS were more stable even if large precipitation occurred.

The Influence of Secondary Phase on Impact Toughness of Alloyed Iron Aluminides

2020 ◽  
Vol 405 ◽  
pp. 145-150
Author(s):  
Martin Švec ◽  
Adam Hotař ◽  
Věra Vodičková ◽  
Vojtěch Keller
Keyword(s):  
Impact Toughness ◽  
Room Temperature ◽  
Volume Fraction ◽  
Fracture Behaviour ◽  
Secondary Phase ◽  
Iron Aluminides ◽  
The Other ◽  
Secondary Phases ◽  
Solid Solution Strengthening ◽  
Solution Strengthening

The microstructure and fracture surfaces were investigated for five Fe3Al – based iron aluminides doped by different alloying elements (Nb, Zr + C, Cr) or without addition. Generally, iron aluminides are considered as brittle material at room temperature, therefore the type and distribution of secondary phases affect the fracture behaviour. The influence of present secondary phase particles on impact toughness at room temperature was evaluated in comparison to binary alloy. The type and the volume fraction of particles affect the value of impact toughness significantly – these values decrease with increasing volume fraction of precipitates. On the other hand, the solid solution strengthening improves impact toughness.

scholarly journals Investigation of the Localized Corrosion and Passive Behavior of Type 304 Stainless Steels with 0.2–1.8 wt % B

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2097 ◽  
Author(s):  
Heon-Young Ha ◽  
Jae Jang ◽  
Tae-Ho Lee ◽  
Chihyoung Won ◽  
Chang-Hoon Lee ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Stainless Steels ◽  
Volume Fraction ◽  
Localized Corrosion ◽  
Ingot Metallurgy ◽  
Passive Behavior ◽  
Pitting Corrosion Resistance ◽  
The Matrix ◽  
Type 304

The pitting corrosion resistance and passive behavior of type 304 borated stainless steels (Febalance–18Cr–12Ni–1.5Mn–(0.19, 0.78, and 1.76 wt %)B) manufactured through conventional ingot metallurgy were investigated. The alloys were composed of an austenitic matrix and Cr2B phase, and the volume fraction of Cr2B increased from 1.68 to 22.66 vol % as the B content increased from 0.19 to 1.76 wt %. Potentiodynamic polarization tests measured in aqueous NaCl solutions revealed that the pitting corrosion resistance was reduced as the B content increased and the pits were initiated at the matrix adjacent to the Cr2B phase. It was found that the reduced resistance to pitting corrosion by B addition was due to the formation of more defective and thinner passive film and increased pit initiation sites in the matrix.

Phases Quantification in Duplex Stainless Steels Weldments

2014 ◽  
Vol 698 ◽  
pp. 209-214
Author(s):  
M. Breda ◽  
S.A. Ontiveros Vidal ◽  
Jacopo Basoni ◽  
Irene Calliari
Keyword(s):  
Corrosion Resistance ◽  
Stainless Steels ◽  
Material Properties ◽  
Volume Fraction ◽  
Secondary Compounds ◽  
Duplex Stainless Steels ◽  
Ferrite Phase ◽  
Steel Plates ◽  
Phase Ratio ◽  
Extreme Care

Duplex Stainless Steels (DSS) are very attractive steels and their application is presently of increasing interest, especially as structural materials in aggressive environments. DSS are austeno-ferritic biphasic steels, having an austenite-to-ferrite phase ratio of about one, giving the best combination of mechanical and corrosion-resistance properties. However, these steels must be handled with extreme care, especially if thermal cycles are involved, owing to the formation of dangerous secondary compounds that highly worsen their excellent properties.The production of big pipes requires manufacturing welding operations on steel plates or sheets and the final products must satisfy specific requirements in terms of material properties. DSS approximately contain equal volume fraction of the phases that, in practice, cover a slightly wider range within 40/60 and 60/40. Therefore, since DSS properties depend on phase ratio, ferrite quantification on an industrial scale represents a topic of great interest, which must be as reliable as possible and, at the same time, quickly executable.The present paper gives a comparison of different methods currently employed for ferrite determination in DSS weldments, in order to understand the limits derived from the specific employed technique.

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