Hydrogen induced cracking of X80 pipeline steel

Abstract

The hydrogen-induced cracking (HIC) behavior of X80 pipeline steel was studied by means of electrochemical charging, hydrogen permeation tests, tension test, and scanning electron microscopy (SEM). The experimental results indicate that the increase of charging time and charging current density or the decrease of the solution pH value leads to an increase of the hydrogen content in X80 steel, which plays a key role in the initiation and propagation of HIC. It is found that the majority of macro-inclusions within the as-used X80 steel do not constitute a direct threat to HIC except aluminum oxides, which directly or indirectly lead to HIC. The hydrogen trap density at room temperature is estimated to be pretty high, and this is an essential reason why the steel is sensitive to HIC. After hydrogen charging, the elongation loss rate and area reduction of X80 steel decline obviously, taking a noticeable sign of hydrogen-induced plasticity damages. It is demonstrated that the losses of these plastic parameters have a linear relation to the fracture size due to hydrogen.

Keywords

pipeline steel / hydrogen induced cracking / electrochemical charging / fracture

References

[1] Li W.W., Shen L., Han L.S., et al. Welding experiment on X80 pipeline steel. Hot Work. Technol., 2006, 35(11): 26.

[2] Zhang M., Yao C.W., Fu C., Lu Z.L. Submerged arc welding wire matched with X80 pipeline steel. Trans. China Weld. Inst., 2006, 27(4): 64.

[3] Liang P., Du C.W., Li X.G., et al. Effect of hydrogen on the stress corrosion cracking behavior of X80 pipeline steel in Ku’erle soil stimulated solution. Int. J. Miner. Metall. Mater., 2009, 16(4): 407.

[4] Li Y.T., Du Z., Tao Y.Y., Xiong L.Y. Sulfide stress cracking of X70 pipeline steels. Trans. China Weld. Inst., 2003, 24(3): 76.

[5] Liu Z.Y., Zhai G.L., Li X.G., et al. Effect of deteriorated microstructures on SCC of X70 pipeline steel in acid soil environment. Int. J. Miner. Metall. Mater., 2008, 15(6): 707.

[6] Hardie D., Charles E.A., Lopez A.H. Hydrogen embrittlement of high strength pipeline steels. Corros. Sci., 2006, 48(12): 4378.

[7] Shin S.Y., Hwang B., Lee S., et al. Correlation of microstructure and charpy impact properties in API X70 and X80 line-pipe steels. Mater. Sci. Eng. A, 2007, 458(1–2): 281.

[8] Shterenlikht A., Hashemi S.H., Howard I.C., et al. A specimen for studying the resistance to ductile crack propagation in pipes. Eng. Fract. Mech., 2004, 71(13–14): 1997.

[9] Kong J.H., Zhen L., Guo B., et al. Influence of Mo content on microstructure and mechanical properties of high strength pipeline steel. Mater. Des., 2004, 25(8): 723.

[10] Dong C.F., Li X.G., Liu Z.Y., Zhang Y.G. Hydrogen-induced cracking and healing behaviour of X70 steel. J. Alloys Compd., 2009, 484(1–2): 966.

[11] Zhang T., Chu W.Y., Gao K.W., Qiao L.J. Study of correlation between hydrogen-induced stress and hydrogen embrittlement. Mater. Sci. Eng. A, 2003, 347(1–2): 291.

[12] Pan C., Su Y.J., Chu W.Y., et al. Hydrogen embrittlement of weld metal of austenitic stainless steels. Corros. Sci., 2002, 44(9): 1983.

[13] Ren X.C., Chu W.Y., Li J.X., et al. The effects of inclusions and second phase particles on hydrogen-induced blistering in iron. Mater. Chem. Phys., 2008, 107(2–3): 231.

[14] Liu Z.Y., Li X.G., Du C.W., et al. Effect of inclusions on initiation of stress corrosion cracks in X70 pipeline steel in an acidic soil environment. Corros. Sci., 2009, 51(4): 895.

[15] Yoo J.Y., Jiang J.F., Zhou L.L. The advantage of spicular ferrite pipeline steel X70-The development of transmitting oil & gas pipeline industry in atrocious weather. Trans. China Weld. Inst., 2004, 27(2): 9.

[16] Chu W.Y. Hydrogen Damage and Lag Fracture, 1988 Beijing, Metallurgical Industry Press, 79.

[17] Wang S.H., Luu W.C., Ho K.F., et al. Hydrogen permeation in a submerged arc weldment of TMCP steel. Mater. Chem. Phys., 2003, 77(2): 447.

[18] Banerjee K., Chatterjee U.K. Hydrogen permeation and hydrogen content under cathodic charging in HSLA 80 and HSLA 100 steels. Scripta Mater., 2001, 44(2): 213.

[19] Yen S.K., Huang I.B. Hydrogen permeation tests in laminates: application to grain/grain boundary of AISI430 stainless steel. Corrosion, 2003, 59(11): 995.