Effects of Environmental Factors on Hydrogen Absorption and Sulfide Stress Cracking Susceptibility of Low Alloy Steel

CORROSION ◽  
10.5006/3414 ◽  
2020 ◽  
Vol 76 (7) ◽  
pp. 698-706
Author(s):  
Kenji Kobayashi ◽  
Tomohiko Omura ◽  
Shinji Fujimoto
Keyword(s):  
Environmental Factors ◽  
Partial Pressure ◽  
Hydrogen Concentration ◽  
Critical Stress Intensity Factor ◽  
Low Alloy Steels ◽  
Diffusible Hydrogen ◽  
Solution Ph ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking

In this study, the sulfide stress cracking (SSC) susceptibility of high-strength low alloy steels was investigated quantitatively. Double cantilever beam tests were used to evaluate the effects of environmental factors, namely pH, H2S partial pressure, and temperature, on the SSC. The corrosion rates and the absorbed diffusible hydrogen concentration were also determined. The critical stress intensity factor (KISSC), which signifies the SSC susceptibility, was mainly affected by the H2S partial pressure and the temperature. Even though the solution pH apparently affected the corrosion rate, the influence of pH on KISSC was small. Considering these results, the environmental contribution in each elementary process of the SSC phenomenon was discussed. The estimated local hydrogen concentration at the crack tip area, which clearly depends on H2S partial pressure and temperature, showed good correlation to the KISSC obtained in various sour conditions.

Effect of Testing Temperature on Sulfide Stress Cracking of Low Alloy Steel

CORROSION ◽  
10.5006/2605 ◽  
2018 ◽  
Vol 74 (6) ◽  
pp. 603-612 ◽  
Author(s):  
Kenji Kobayashi ◽  
Tomohiko Omura ◽  
Masakatsu Ueda
Keyword(s):  
Stress Concentration ◽  
Low Temperature ◽  
Hydrogen Concentration ◽  
Environmental Temperature ◽  
High Stress ◽  
Testing Temperature ◽  
Low Alloy Steels ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking

In this study, effects of environmental temperature on susceptibility to sulfide stress cracking (SSC)—a type of hydrogen embrittlement (HE) occurring in sour environments—of low alloy steels were investigated from the perspective of hydrogen entry, absorption, and accumulation. SSC susceptibility was evaluated using a double cantilever beam (DCB) test and a four-point bend (4PB) test in sour environments at several testing temperatures. 4PB test specimens included notched and un-notched specimens to investigate influences of stress concentration and local stress. In the case of evaluation methods using specimens with high-stress concentration area, a decrease in testing temperature from room temperature to 4°C significantly increased SSC susceptibility. Hydrogen entry and absorption behaviors were also evaluated at several testing temperatures using a hydrogen permeation test. The hydrogen concentration at the plastic deformed area increased remarkably with decreasing testing temperature. It is considered that the influence of testing temperature is due to hydrogen concentration at the stress concentration area with plastic deformation. In a low temperature condition, the degree of hydrogen accumulation at the crack tip areas of a DCB specimen or crack initiation site of a 4PB specimen could be higher than that in a higher temperature condition. When steels are applied to low temperature conditions with H2S, a prior material evaluation reproducing both environmental temperature and actual stress condition is needed.

Effect of Buffer System on the Sulfide Stress Cracking Susceptibility of Low-Alloy Steel

CORROSION ◽  
10.5006/2626 ◽  
2018 ◽  
Vol 74 (7) ◽  
pp. 788-800
Author(s):  
Kenji Kobayashi ◽  
Tomohiko Omura ◽  
Hisashi Amaya
Keyword(s):  
Partial Pressure ◽  
Buffer System ◽  
Low Alloy Steel ◽  
High Co2 ◽  
Co2 Partial Pressure ◽  
Stress Cracking ◽  
Test Conditions ◽  
Sulfide Stress ◽  
Ratio Condition ◽  
Sulfide Stress Cracking

The effects of a buffer system in test solution and CO2 partial pressure on sulfide stress cracking (SSC) susceptibility of low-alloy steel were investigated under pH 4.0 at 0.03 MPa H2S partial pressure. A double cantilever beam test was used to quantitatively evaluate SSC susceptibility. The corrosion rates and absorbed diffusible hydrogen concentration were also evaluated. Acetic acid/sodium acetate (acetate buffered solution) and carbonic acid/bicarbonate (bicarbonate buffered solution) buffered solutions were used as buffer systems in this study. From the results, in atmospheric pressure tests, KISSC values in bicarbonate buffered solutions were equivalent to or lower than those in acetate buffered solutions. In high CO2 partial pressure conditions, KISSC values in bicarbonate buffered solutions were much higher than those in acetate buffered solutions. At a high CO2 partial pressure and H2S partial pressure (pCO2/pH2S) ratio condition, hydrogen entry is considered to be greatly prevented by corrosion products probably containing amorphous iron carbonate. Presence of the corrosion product with high protectiveness produced in the high pCO2/pH2S ratio condition suggests the possibility that conventional test conditions using acetate buffered solutions are conservative or are equivalent test conditions for actual field conditions.

Low Alloy Steels in Hydrogen Sulfide Environment

CORROSION ◽  
1982 ◽  
Vol 38 (3) ◽  
pp. 156-167 ◽  
Author(s):  
Yuichi Yoshino
Keyword(s):  
Hydrogen Sulfide ◽  
Hydrogen Absorption ◽  
Carbide Precipitation ◽  
Low Alloy Steels ◽  
Matrix Interface ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Alloy Steels ◽  
Carbide Matrix ◽  
Sulfide Stress Cracking

Abstract The effect of chemical composition on the behavior of low alloy steels in a hydrogen sulfide environment was studied with regard to corrosion, hydrogen absorption, and sulfide stress cracking. Results were interpreted in connection with microstructure and carbide precipitation. The addition of chromium results in the promotion of hydrogen absorption presumably due to the precipitation of incoherent carbides, thereby reducing, in general, the resistance to SSC. Fine coherent carbides appear to be beneficial, or at least not detrimental, to SSC resistance; e.g., Mo2C, VC, TiC, and NbC. Microstructure seems to affect both hydrogen absorption and SSC resistance largely through the trapping behavior of hydrogen at the carbide/matrix interface.

scholarly journals Sulfide Stress Cracking of C-110 Steel in a Sour Environment

2021 ◽  
Vol 2 (3) ◽  
pp. 376-396
Author(s):  
Sagar Tale ◽  
Ramadan Ahmed ◽  
Rida Elgaddafi ◽  
Catalin Teodoriu
Keyword(s):  
Partial Pressure ◽  
Hydrogen Permeation ◽  
Pressure Ratio ◽  
Optical Microscope ◽  
Mixed Gas ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking ◽  
Partial Pressure Ratio ◽  
Grade Steel

The scope of this study includes modeling and experimental investigation of sulfide stress cracking (SSC) of high-strength carbon steel. A model has been developed to predict hydrogen permeation in steel for a given pressure and temperature condition. The model is validated with existing and new laboratory measurements. The experiments were performed using C-110 grade steel specimens. The specimens were aged in 2% (wt.) brine saturated with mixed gas containing CH4, CO2, and H2S. The concentration H2S was maintained constant (280 ppm) while varying the partial pressure ratio of CO2 (i.e., the ratio of partial pressure of CO2 to the total pressure) from 0 to 15%. The changes occurring in the mechanical properties of the specimens were evaluated after exposure to assess material embrittlement and SSC corrosion. Besides this, the cracks developed on the surface of the specimens were examined using an optical microscope. Results show that the hydrogen permeation, and subsequently SSC resistance, of C-110 grade steel were strongly influenced by the Partial Pressure Ratio (PPR) of CO2 when the PPR was between 0 and 5%. The PPR of CO2 had a limited impact on the SSC process when it was between 10 and 15 percent.

The Role of Hydrogen in Sulfide Stress Cracking of Low Alloy Steels

CORROSION ◽  
1984 ◽  
Vol 40 (5) ◽  
pp. 240-245 ◽  
Author(s):  
B. J. Berkowitz ◽  
F. H. Heubaum
Keyword(s):  
Low Alloy Steels ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Alloy Steels ◽  
Sulfide Stress Cracking

Sulfide stress cracking of nickel-containing low-alloy steels

2015 ◽  
Vol 33 (1-2) ◽  
pp. 99
Author(s):  
Mariano Kappes ◽  
Mariano Iannuzzi ◽  
Raúl B. Rebak ◽  
Ricardo M. Carranza
Keyword(s):  
Low Alloy Steels ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Alloy Steels ◽  
Sulfide Stress Cracking
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