Inhibitory effect of oxygen on hydrogen‐induced fracture of A333 pipe steel

Abstract

The effect of oxygen contained in hydrogen gas environment as an impurity on hydrogen environment embrittlement (HEE) of A333 pipe steel was studied through the fracture toughness tests in hydrogen gases. The oxygen contents in the hydrogen gases were 100, 10, and 0.1 vppm. A significant reduction in the J‐Δa curve was observed in the hydrogen with 0.1‐vppm oxygen. Under given loading conditions, the embrittling effect of hydrogen was completely inhibited by 100 vppm of oxygen. In the case of the hydrogen with 10‐vppm oxygen, initially the embrittling effect of hydrogen was fully inhibited, and then subsequently appeared. It was confirmed that 1‐vppm oxygen reduced the embrittling effect of hydrogen. The results can be explained by the predictive model of HEE proposed by Somerday et al.

Coadsorption of CO and H2 on an Iron Surface and Its Implication on the Hydrogen Embrittlement of Iron

“…The gas environments to which the specimen was exposed were high-purity H 2 , 100 volume ppm of CO with added H 2 , and high-purity N 2 . Since O 2 contained in H 2 acts as a strong inhibitor of hydrogen embrittlement 40 and the effect appears for O 2 concentration above 0.3 volume ppm in the fracture toughness test, the O 2 concentration of all gases was maintained at less than 0.1 volume ppm. In addition, the CO concentration in the high-purity H 2 and N 2 gases was also maintained at less than 0.1 volume ppm.…”

Effect of Gas Pressure on Hydrogen Environment Embrittlement of Carbon Steel A106 in Carbon Monoxide Mixed Hydrogen Gas

“…[17] A single crosshead speed that can be expected to be sufficiently slow to saturate the effect of hydrogen on the HEE susceptibility was chosen in this study. [9] In some fracture toughness tests conducted in the present study, the crack opening displacement, COD, exceeded the capacity of the clip gauge measurement before the J-Da curve crossed the 0.2 mm offset line. In this case, the CO mitigation effect was discussed based on the comparison of the J-Da curves.…”

“…Regarding H 2 and N 2 gases, the CO and O 2 contents in the gases were maintained at less than 0.1 vppm during the fracture toughness test since these impurities have a mitigation effect on the HEE. [4][5][6][7][8][9][10][11] For instance, the effect of O 2 of ‡ 0.3 vppm was confirmed not to be negligible in the fracture toughness test of pipe steel. [9] In the present study, the H 2 and N 2 gases that were not intentionally mixed with CO were termed high-purity H 2 and N 2 , respectively.…”

“…[4][5][6][7][8][9][10][11] For instance, the effect of O 2 of ‡ 0.3 vppm was confirmed not to be negligible in the fracture toughness test of pipe steel. [9] In the present study, the H 2 and N 2 gases that were not intentionally mixed with CO were termed high-purity H 2 and N 2 , respectively. The CO content in the H 2 with added CO varied from 10 to 50,000 vppm.…”

“…[2] Furthermore, Yamabe et al developed an aluminium-based coating that shows a high resistance against hydrogen uptake into the material in a 100 MPa H 2 environment at 543 K. [3] However, a gas impurity contained in H 2 is well recognized to affect the HEE if the impurity has an interaction with the Fe surface. For instance, O 2 and CO have been shown to mitigate susceptibility to HEE, [4][5][6][7][8][9][10][11] while H 2 S enhances HEE susceptibility. [4] CO 2 and CH 4 are known to have no effect on HEE susceptibility due to their lack of interaction with the Fe surface.…”