Study of the non-metallic inclusions in duplex stainless steels performed by a thermodynamic formalism for non-dilute alloys

2003 ◽  
Vol 100 (1) ◽  
pp. 65-72
Author(s):  
C. Mapelli
Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1750
Author(s):  
Aleksandr Sergeevich Fedorov ◽  
Andrey Igorevich Zhitenev ◽  
Darya Andreevna Strekalovskaya ◽  
Aleksandr Aleksandrovich Kur ◽  
Alexey Aleksandrovich Alkhimenko

The properties of duplex stainless steels (DSSs) depend on the ferrite–austenite ratio, on the content of secondary phases and on the contamination with non-metallic inclusions. To assess the quality of DSSs, it is necessary to use an integrated approach which includes controlling for the volume fraction, the morphology and the distribution of all phases and non-metallic inclusions. Samples of several grades of DSSs were obtained using various heat treatments, such as solution annealing and quenching from 1050 to 1250 °C to obtain different amounts of ferrite and to provoke annealing at 850 °C to precipitate σ-phase. As a result, a metallographic technique of phase analysis in DSSs based on selective etching and subsequent structure parameters estimation according to ASTM E1245 was developed. We demonstrated that the developed method of quantitative analysis based on selective etching and metallographic analysis according to ASTM E1245 allows us to obtaining much more accurate results, compared to the point count method described in ASTM E562 and to the XRD method.


Alloy Digest ◽  
2012 ◽  
Vol 61 (4) ◽  

Abstract Stoody AP stainless steel wires are all-position wires. The nickel in this product will achieve a good balance of austenite and ferrite in lean duplex stainless steels. This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on forming and joining. Filing Code: SS-1118. Producer or source: Stoody Company.


CORROSION ◽  
2011 ◽  
Vol 67 (2) ◽  
pp. 025004-1-025004-7 ◽  
Author(s):  
D. Han ◽  
Y. Jiang ◽  
B. Deng ◽  
L. Zhang ◽  
J. Gao ◽  
...  

Abstract A simple and rapid electrochemical method for the evaluation of crevice corrosion in duplex stainless steels (DSS) is described. Three types of DSS—namely, UNS S32101, UNS S31803, and UNS S32750—were tested in 1 mol/L sodium chloride (NaCl) solutions. Results showed good reproducibility with a typical standard deviation of below 3°C. The critical pitting temperature (CPT) for the same specimens was also investigated in 1 mol/L NaCl solutions. An approximately 20°C decrease from CPT to critical crevice temperature (CCT) was observed and subsequently explained. Then, the morphologies of crevice corrosion were studied using scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM/EDS) method. The SEM/EDS study revealed that the ferrite phase was the site where preferential dissolution took place at the initiation step of crevice corrosion, which was in accordance with the prediction by calculating the critical crevice index. Moreover, repassivation was detected with the development of crevice corrosion. The reason was clarified by combining the results obtained with a successful diffusion model, and eventually the crevice corrosion progress was illustrated schematically.


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