Inhibition of nitrogen uptake by SiO2 surface films formed on stainless steel during annealing in H2/N2 atmospheres

1988 ◽  
Vol 19 (12) ◽  
pp. 3045-3055 ◽  
Author(s):  
J. F. Kirner ◽  
M. R. Anewalt ◽  
E. J. Karwacki ◽  
A. L. Cabrera
Keyword(s):  
Stainless Steel ◽  
Nitrogen Uptake ◽  
Surface Films ◽  
Sio2 Surface

scholarly journals Technical Note: Characterization of Corrosion Films Formed on Austenitic Stainless Steel in Supercritical CO2 Containing H2O and O2

CORROSION ◽  
10.5006/2726 ◽  
2018 ◽  
Vol 74 (10) ◽  
pp. 1047-1053 ◽  
Author(s):  
Richard P. Oleksak ◽  
John P. Baltrus ◽  
Lucas Teeter ◽  
Margaret Ziomek-Moroz ◽  
Ömer N. Doğan
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Aqueous Phase ◽  
Stainless Steels ◽  
Photoelectron Spectroscopy ◽  
Supercritical Co2 ◽  
Carbon Capture And Storage ◽  
Technical Note ◽  
Structure Characteristic ◽  
Surface Films

Future technologies require structural alloys resistant to corrosion in supercritical CO2 (sCO2) fluids containing impurities such as H2O and O2. Traditional pipeline steels are potentially unsuitable for these environments and more corrosion resistant alloys such as stainless steels might be required. Little is known about the corrosion products formed on, and hence the processes which control corrosion of, stainless steels in impure sCO2 environments. In this study, austenitic stainless steel 347H (UNS S34709) was exposed to sCO2 containing H2O and O2 at 8 MPa and 50°C or 250°C, and separately to the aqueous phase in equilibrium with the sCO2 at 50°C, to simulate conditions expected in sCO2-based power cycles and carbon capture and storage pipelines. Only thin (<20 nm) surface films formed after 500 h resulting in small mass changes and corrosion rates <10−4 mm/y, suggesting the material resists significant degradation in these environments. X-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize the corrosion films in detail. Exposure to the aqueous phase resulted in a thin (<5 nm) Cr-oxide and/or -hydroxide passive film, while exposure to sCO2 phases resulted in a multilayer Fe-rich oxide structure characteristic of a gas-phase oxidation process.

Deliquescence of NaCl and Atmospheric Corrosion of 316L Stainless Steel

2017 ◽  
Vol 1142 ◽  
pp. 8-13
Author(s):  
Ahmed Al Mehrzi ◽  
Yong Sun Yi ◽  
Pyung Yeon Cho ◽  
Sara Al Saadi ◽  
Ji Sung Lee ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Relative Humidity ◽  
Atmospheric Corrosion ◽  
Steel Surface ◽  
316L Stainless Steel ◽  
Chloride Concentration ◽  
Atmospheric Condition ◽  
Stainless Steel Surface ◽  
Surface Films ◽  
Pit Initiation

Water droplets formed by the deliquescence of pre-deposited NaCl on 316L stainless steel were investigated. Different total weights of NaCl particles between 0.0005 g and 0.01 g were deposited on 316L stainless steel surface, which were exposed to an atmospheric condition at 80oC and relative humidity of 80% until NaCl droplets were stabilized. The volume of NaCl droplet was linearly proportional to the total weights of pre-deposited NaCl and consequently the chloride concentration in droplets, ranging from 3 to 6 M, did not depend on the NaCl weights. After exposed to the NaCl droplets at 80oC and relative humidity of 80% over 5, 10, and 15 days, all 316L stainless steel samples suffered from pitting. The Cl- ions in the surface films of samples were measured by ToF SIMS. The pit densities on samples were well correlated with the Cl- intensities in the surface films. These results suggest that the pit initiation under NaCl droplets by deliquescence is caused by the Cl- ions either incorporated into surface films or penetrated through them.

Effect of Surface Treatment on Corrosion Resistance of 304 Stainless Steel Implants in Tyrode Solution

2014 ◽  
Vol 59 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Z. Ahmadian ◽  
I. Danaee ◽  
M.A. Golozar
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Surface Preparation ◽  
Passive Layer ◽  
Physiological Solution ◽  
304 Stainless Steel ◽  
Surface Films ◽  
Cyclic Polarization ◽  
Preparation Methods ◽  
Pit Initiation

Abstract The effect of different surface preparation methods such as mechanical, chemical and electrochemical surface preparation on the formation, stability and deterioration of surface films formed on austenitic 304 stainless steel was investigated in Tyrode’s physiological solution by cyclic polarization curves, AC impedance measurements surface techniques. A hysteresis loop in a cyclic polarization curve was obtained that indicates a delay in repassivation of an existing pit when the potential is scanned cathodically. Electrolytic polishing and ultrasonic cleaning improves corrosion resistance by increasing the value of the corrosion potential and breakdown potential of the passive layer as well as the pit initiation potential. After mechanical polishing no perfect passivation region was observed. Change in surface fractal is in good agreement with the result obtained from height roughness factor of AFM.

Prediction of Properties in Type 347 Austenitic Stainless Steel after Long-Term Service at High Temperatures

2007 ◽  
Vol 539-543 ◽  
pp. 4920-4925 ◽  
Author(s):  
Jan Olof Nilsson
Keyword(s):  
Stainless Steel ◽  
Elevated Temperature ◽  
Austenitic Stainless Steel ◽  
Nitrogen Uptake ◽  
Σ Phase ◽  
Prediction Of Properties ◽  
Software Packages ◽  
Evolution Of Microstructure ◽  
Good Agreement

The evolution of microstructure during production and elevated temperature service of type 347 austenitic stainless steel in the temperature range 700-800°C was modelled using commercial software packages such as Thermo-Calc and DICTRA and characterized using various microscopical techniques. The growth and coarsening of niobium carbonitrides and σ- phase were modelled as well as nitrogen uptake. Good agreement between predictions and microstructural observations was found.

An AEM study of phosphorus segregation in a stainless steel

1983 ◽  
Vol 41 ◽  
pp. 200-201
Author(s):  
A. R. Pelton ◽  
K. H. Westmacott
Keyword(s):  
Stainless Steel ◽  
Grain Boundaries ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Weight Percent ◽  
Surface Films ◽  
Phosphorus Segregation ◽  
Ferritic Alloys ◽  
Austenitic Alloys ◽  
Impurity Elements

The deleterious effects on the mechanical properties of phosphorus segregation to grain boundaries in ferritic alloys are well documented in the metallurgical literature. An understanding of this recurring problem has profited from the recent application of analytical electron microscopy (AEM). EDS analysis has allowed the detection of phosphorus in thin films at prior austenite grain boundaries and in association with intergranular carbides. Although austenitic alloys also suffer from property degradation due to segregated impurity elements, comparable studies have not been conducted on these materials. The purpose of this paper, therefore, is to report the results from an AEM investigation of phosphorus segregation in an austenitic stainless steel. Of particular concern is the effect of grain boundary type on phosphorus segregation and precipitation.An Fe-18 Cr-10 Ni-0.3P (weight percent) steel was quenched from 1150°C and aged between 400-700°C. Samples were prepared by standard polishing techniques; those samples analyzed by EDS were lightly ion-beam milled to remove surface films formed by the electropolishing.

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