scholarly journals Investigation on Solid-State Phase Transformations in a 2510 Duplex Stainless Steel Grade

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 967
Author(s):  
Irene Calliari ◽  
Marco Breda ◽  
Claudio Gennari ◽  
Luca Pezzato ◽  
Massimo Pellizzari ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Phase Precipitation ◽  
Σ Phase ◽  
Heat Treated ◽  
Key Factor ◽  
Super Duplex Stainless Steels ◽  
Welding Processes

Duplex and Super Duplex Stainless Steels are very prone to secondary phases formation related to ferrite decomposition at high temperatures. In the present paper the results on secondary phase precipitation in a 2510 Duplex Stainless Steel, heat-treated in the temperature range 850–1050 °C for 3–30 min are presented. The precipitation starts at grain boundaries with a consistent ferrite transformation for very short times. The noses of the Time–Temperature–Precipitation (TTP) curves are at 1000 °C for σ-phase and at 900 °C for χ-phase, respectively. The precipitation sequence involves a partial transformation of χ into σ, as previously evidenced in 2205 and 2507 grades. Furthermore, the experimental data were compared to the results of Thermo-Calc calculations. Understanding and ability to predict phase stability in 2510 duplex stainless steel is a key factor to design optimal welding processes that avoid any secondary phase precipitation in the weld bead as well as in the heat-affected zone.

scholarly journals Investigation on Solid State Phase Transformations in a 2510 Duplex Stainless Steel Grade

2020 ◽  
Author(s):  
Irene Calliari ◽  
Marco Breda ◽  
Claudio Gennari ◽  
Luca Pezzato ◽  
Massimo Pellizzari ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Phase Precipitation ◽  
Heat Treated ◽  
Super Duplex Stainless Steels ◽  
Short Times ◽  
Stainless Steel Heat ◽  
Steel Heat

Duplex and Super Duplex Stainless Steels are very prone to secondary phases formation related to ferrite decomposition at high temperatures. In the present paper the results on secondary phase precipitation in a 2510 Duplex Stainless Steel, heat treated in the temperature range 850-1050 °C for 3-30 minutes are presented. The precipitation starts at grain boundaries with a consistent ferrite transformation for very short times. The noses of the TTP curves are at 1000 °C for σ-phase and at 900 °C for χ-phase, respectively. The precipitation sequence involves a partial transformation of χ into σ, as previously evidenced in 2205 and 2507 grades. Furthermore, the experimental data were compared to the results of Thermo-Calc calculations.

Effect of Secondary Phase Precipitation on Impact Toughness of Duplex Stainless Steel

2017 ◽  
Vol 889 ◽  
pp. 138-142 ◽  
Author(s):  
Amit Powar ◽  
Amol Gujar ◽  
Niketan Manthani ◽  
Vinayak Pawar ◽  
Rajkumar Singh
Keyword(s):  
Stainless Steel ◽  
Impact Toughness ◽  
Duplex Stainless Steel ◽  
Solution Treatment ◽  
Secondary Phase ◽  
Phase Precipitation ◽  
X Ray Diffraction ◽  
Σ Phase ◽  
Material Solution ◽  
The Impact

Duplex Stainless Steel (DSS) combines good mechanical strength and ductility with moderate to good corrosion resistance in a variety of environments. DSS are prone to the formation of various intermetallic phases (σ, χ, π, R), carbides (M23C6) and nitrides (Cr2N), when it exposed to temperatures lower than 1000°C. This study focuses on effect of secondary phase precipitation on impact toughness of ASTM A182 DSS. Cylindrical bar of DSS was open die forged in the temperature range of 1200-1050°C. After the forging, the bar was slow cooled by covering it with ceramic wool. This leads to the formation of σ phase at the ferrite/austenite interfaces and significantly reduced the impact toughness of the material. Solution treatment was done at different temperature and effect on toughness studied. The microstructural changes produced as consequences of the distinct test condition have been analyzed by means of optical and electron microscopy, X-ray diffraction.

Influence of Sigma Phase Precipitation on Pitting Corrosion of 2507 Super-Duplex Stainless Steel

2010 ◽  
Vol 658 ◽  
pp. 380-383 ◽  
Author(s):  
Ying Han ◽  
De Ning Zou ◽  
Wei Zhang ◽  
Jun Hui Yu ◽  
Yuan Yuan Qiao
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Ambient Temperature ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Super Duplex Stainless Steel ◽  
Phase Precipitation ◽  
Pitting Potential ◽  
Σ Phase ◽  
Pitting Corrosion Resistance

Specimens of 2507 super-duplex stainless steel aging at 850°C for 5 min, 15 min and 60 min were investigated to evaluate the pitting corrosion resistance in 3.5% NaCl solution at 30°C and 50°C. The results are correlated with the microstructures obtained with different aging time. The precipitation of σ phase remarkably decreases the pitting corrosion resistance of the steel and the specimen aged for 60 min presents the lowest pitting potential at both 30°C and 50°C. With increasing the ambient temperature from 30°C to 50°C, the pitting potential exhibits a reduction tendency, while this tendency is less obviously in enhancing the ambient temperature than in extending the isothermal aging duration from 5 to 60 min. SEM analysis shows that the surrounding regions of σ phase are the preferable sites for the formation of corrosion pits which grew up subsequently. This may be attributed to the lower content of corrosion resistance elements in these regions formatted with σ phase precipitation.

The Study on Welding HAZ Microstructure of SAF 2507 Duplex Stainless Steel by Simulation Tests

2014 ◽  
Vol 804 ◽  
pp. 277-280 ◽  
Author(s):  
Ren Long Tao ◽  
Jie Liu ◽  
Guang Wei Fan ◽  
Xu Chang
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Cooling Rate ◽  
Significant Influence ◽  
Thermal Simulation ◽  
Cooling Time ◽  
Phase Precipitation ◽  
Σ Phase

Thermal simulation by GLEEBLE3800 is adopted to obtain the simulated welding HAZ microstructures in SAF 2507 duplex stainless steel with the GLEEBLE3800 thermal simulation machine. The simulation peak temperatures are 800oC, 900oC, 950oC, 1000oC, 1050oC and 1100oC, The cooling velocities are t12/8=3.6s, 7s, 20s and 40s (t12/8 is cooling time of 1200oC to 800oC which is used to describe the cooling rate). The results indicate that the peak temperatures have significant influence on the microstructures of austenite and ferrite. At 900oC, the content of σ phase precipitation reaches the maximum, which is distributed mainly in α or at α/γ junction. When the temperature is set above 1050oC, the σ phase disappears. A faster cooling rate passing through 800~1050oC is required to avoid brittle σ phase precipitation.

Heat Treatment Effect on Pitting Corrosion of Super Duplex Stainless Steel UNS S32750 GTA Welds

2013 ◽  
Vol 746 ◽  
pp. 467-472 ◽  
Author(s):  
In June Moon ◽  
Bok Su Jang ◽  
Jin Hyun Koh
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Super Duplex Stainless Steel ◽  
Σ Phase ◽  
Gas Tungsten Arc ◽  
Weld Metals ◽  
Pitting Corrosion Resistance ◽  
Heat Treated

The purpose of this study was to investigate the effect of heat treatment (930°C, 1080°C, 1230°C) followed by quenching on the pitting corrosion resistance, sigma phase precipitation, and microstructural change of a super duplex stainless steel (UNS S32750) welds made by gas tungsten arc (GTA). Based on the microstructural examination, the σ phase was formed in welds heat treated at 930°C while there were little σ phases formed in welds experienced the relatively fast cooling from 1080°C and 1230°C. Accordingly, the most weight loss due to pitting corrosion occurred in the as received base and weld metals heat treated at 930°C. It was confirmed that the pitting corrosion occurred in the phase boundaries of ferrite/sigma and austenite/sigma.

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