scholarly journals Characterization of Native Oxide and Passive Film on Austenite/Ferrite Phases of Duplex Stainless Steel Using Synchrotron HAXPEEM

2019 ◽  
Vol 166 (11) ◽  
pp. C3336-C3340 ◽  
Author(s):  
M. Långberg ◽  
C. Örnek ◽  
F. Zhang ◽  
J. Cheng ◽  
M. Liu ◽  
...  
2019 ◽  
Vol 166 (16) ◽  
pp. C609-C616 ◽  
Author(s):  
Ehsan Rahimi ◽  
Ali Rafsanjani-Abbasi ◽  
Ali Davoodi ◽  
Saman Hosseinpour

2016 ◽  
Vol 23 (03) ◽  
pp. 1650013 ◽  
Author(s):  
MOHAMMED ASIF M. ◽  
KULKARNI ANUP SHRIKRISHNA ◽  
P. SATHIYA

The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080[Formula: see text]C, 1150[Formula: see text]C and 1200[Formula: see text]C with 15[Formula: see text]min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080[Formula: see text]C followed by water quench and at 1150[Formula: see text]C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov–Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100[Formula: see text]C and that for oil quenching was around 1140[Formula: see text]C. The pit depths were found to be in the range of 100[Formula: see text]nm and width of 1.5–2[Formula: see text][Formula: see text]m.


2021 ◽  
Vol 63 (6) ◽  
pp. 505-511
Author(s):  
Songkran Vongsilathai ◽  
Anchaleeporn Waritswat Lothongkum ◽  
Gobboon Lothongkum

Abstract A new duplex 25Cr-3Ni-7Mn-0.66 N alloy was prepared in a vacuum arc re-melting furnace and characterized by metallographic and EPMA methods. Its corrosion behavior was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and a Mott-Schottky (M-S) analysis in artificial seawater at room temperature and compared with those of super and normal commercial duplex stainless steel (SDSS and DSS). No significant difference in the open circuit potentials and pitting potentials was observed. Its passive film current density lies between those of SDSS and DSS. This was confirmed by EIS analysis. A pit attack was observed on the δ-phase for all duplex samples, because the PREN16 of the δ-phase was lower than that of the γ-phase. From the Mott-Schottky analysis, the passive films were found to be composed of bi-layer structures, a p-type semiconductor inner layer, and a n-type semiconductor outer layer. The degree of defect as well as the effect of nitrogen in passive film layer are discussed with respect to the point defect model.


2018 ◽  
Vol 31 (8) ◽  
pp. 798-806 ◽  
Author(s):  
Gang Liu ◽  
Shi-Lei Li ◽  
Hai-Long Zhang ◽  
Xi-Tao Wang ◽  
Yan-Li Wang

2020 ◽  
Vol 67 (3) ◽  
pp. 313-320 ◽  
Author(s):  
Chuanbo Zheng ◽  
Jiayan Huang ◽  
Gua Yi

Purpose This paper aims to study the effect of current density of hydrogen charging on the semiconductor properties and pitting initiation of 2205 duplex stainless steel (DSS) passivation film. Design/methodology/approach In this work, the 2205 DSS is pre-hydrogenated and passivated. Then, the passivation film is tested by electrochemical impedance method, Mott–Schottky curve method and dynamic potential scanning method. The influences of hydrogen on the properties of the passivation film and the corrosion behavior of the matrix were studied by analyzing the curves obtained in the electrochemical test. The surface of the passivation film after pre-hydrogenation and anodic polarization was observed by using the ultra-depth three-dimensional microscopy and the scanning electron microscope. The integrity, density and corrosion morphology of the passivation film were studied and discussed. Findings With the increase of the hydrogen current density, the growth of the passivation film is hindered, the concentrations of donor and acceptor in the film are increased, the conductivity of the passivation film increases. In the anodic polarization, the dimensional passive current density increases with the increase of the hydrogen current density, and the pitting potential is reversed, the more likely the sample is pitting. In general, hydrogen hinders the formation of the passive film on duplex stainless steel, which increases the concentration of point defects in the passive film. Finally, the passive film is easy to crack and pitting. Originality/value The performance of passive film is an important condition to influence the corrosion behavior of stainless steel. However, little research has been done on the effects of hydrogen on the electrochemistry and pitting sensitivity of 2205 DSS passivation films. The effect of hydrogen on semiconductor properties and pitting initiation of 2205 DSS passivation film is needed to be investigated.


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