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Hydrogen-induced cracking of carbon seamless steel tube materials

Date:2018-03-23    View:1078      Tag:Hydrogen-induced cracking of carbon seamless steel tube materials
Carbon seamless steel tube are mainly used for transporting high pressure oil and gas near the wellhead. As the corrosion of hydrogen sulfide becomes more and more serious, the development of sulfur-resistant seamless pipes is imminent, and the sulfur resistance is the key. The effect of Cu and Ni on the HIC resistance of the seamless steel pipe material and the S content in the steel were investigated. The influence of the addition of Cu and Ni on the HIC performance was also examined. Hydrogen bubbling sensitivity.

1. experiment method
According to the iso3183 standard, the ingot method smelts 7T grade 1t steel ingots in the laboratory. After forging, the perforation, the top pipe and the table were reduced, the pipe was cut to 20 mm, 100 mm, 5 mm××, and then immersed in the solution and prepared according to the standard. After 96 hours, the specimen was removed and perpendicular to the cross section. The three parameters of crack length ratio CLR, crack thickness CTR and crack sensitivity CSR were calculated by metallographic method. (HIC) susceptibility.

2. Factors Affecting HIC Performance
1) A large number of studies have shown that in the range of 1 to 6, the sensitivity of hydrogen bubbling decreases with increasing ph value. When the pH is >6, hydrogen bubbling does not occur.
2) H2S concentration. The higher the concentration of hydrogen sulfide, the greater the sensitivity of hydrogen bubbling.
3) Chloride ion. The presence of chloride ions increases the corrosion rate and increases the hydrogen bubbling sensitivity in the pH range of 3.5 to 4.5.
4) Temperature. 25 degrees, maximum CLR, hydrogen bubble sensitivity. When the temperature is lower than 25°C, the hydrogen corrosion reaction and diffusion rate are accelerated, and the hydrogen bubbling sensitivity is improved. After 25 hours, the concentration of hydrogen sulfide decreased and the hydrogen-induced sensitivity decreased.
5) Time. With 96 h contrast, under normal conditions, as the test time increases, the degree of corrosion increases.
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