Effect of Deep Sea Pressures on the Corrosion Behavior of X65 Steel in the Artificial Seawater

doi:10.1007/s40195-018-0856-8

Abstract

Abstract:

The corrosion behaviors of X65 steel in the artificial seawater at different hydrostatic pressures are investigated by potentiodynamic polarization measurements, electrochemical impedance spectroscopy measurements and weight loss measurements. The corroded morphologies and the corrosion products are also investigated by scanning electron microscopy, X-ray diffraction analysis and Raman analysis. The results show that the corrosion current increases as the hydrostatic pressure increases. The charge transfer resistance decreases as the hydrostatic pressure increases. The corrosion products are mainly composed of γ-FeOOH and Fe₃O₄ at the atmospheric pressure, while the main components are γ-FeOOH, Fe₃O₄, and γ-Fe₂O₃ at the high pressure. The hydrostatic pressure accelerates the corrosion of X65 steel due to its effect on the chemical and physical properties of corrosion products, including the promoted reduction of γ-FeOOH and the wider and deeper cracks on the corrosion products layer.

Key words: X65 steel, Deep sea pressures, Electrochemical measurements, Corrosion

Qiu-Shi Li, Shun-Zhong Luo, Xu-Teng Xing, Jing Yuan, Xin Liu, Ji-Hui Wang, Wen-Bin Hu. Effect of Deep Sea Pressures on the Corrosion Behavior of X65 Steel in the Artificial Seawater[J]. Acta Metallurgica Sinica (English Letters), 2019, 32(8): 972-980.

Figures/Tables 15

Table 1 Chemical compositions of X65 steel (wt%)

Alloy	C	Si	Mn	Ni	Cr	Mo	Cu	V	Nb	P	S
X65	0.09	0.26	1.30	0.15	0.04	0.17	0.13	0.04	0.03	0.007	0.002

Fig. 1 Schematic diagram of the high-pressure device: (1) manual hydraulic press, (2) liquid inlet pipe, (3) hanging rod, (4) reference electrode, (5) working electrode, (6) counter electrode, (7) pressure gauge, (8) electrochemical workstation, (9) temperature controller

Table 2 The expected Raman peaks for iron oxide compounds

Compounds	Compositions	Raman shifts (cm^-1)	References
Lepidocrocite	γ-FeOOH	255, 380, 1307	[16, 17]
Maghemite	γ-Fe₂O₃	358, 499, 678, 710	[18]
Magnetite	Fe₃O₄	297, 532, 616, 670, 680	[16, 17, 19]
Goethite	α-FeOOH	390, 485, 554	[16, 17]
Hematite	α-Fe₂O₃	292, 415, 500, 615, 1320	[17, 19]

Fig. 2 Polarization curves for X65 steel exposed to the 3.5 wt% NaCl solution at different pressures

Table 3 Evolutions of polarization parameters for X65 steel immersed in the 3.5 wt% NaCl solution at different pressures

Pressure (MPa)	Parameters
Pressure (MPa)	I_corr (A cm^-2)	E_corr (V)
0.1	1.748?×?10^-5	-?0.4986
4	3.186?×?10^-5	-?0.5047
8	3.778?×?10^-5	-?0.5175
12	4.885?×?10^-5	-?0.5224

Fig. 3 Electrochemical impedance spectra for X65 steel exposed to the 3.5 wt% NaCl solution at different pressures. a Nyquist plot, b Bode plots

Fig. 4 The equivalent circuit model used for EIS fitting analysis

Table 4 Evolutions of electrochemical impedance parameters for X65 steel immersed in the 3.5 wt% NaCl solution at different pressures

Pressure (MPa)	Parameters
Pressure (MPa)	R_s (Ω cm²)	α	Q_dl (mF cm^-2)	R_p (Ω cm²)	Chi square value (×?10^-3)
0.1	2.537	0.78	1.009	1319.0	1.140
4	2.866	0.69	2.806	1237.0	2.633
8	2.753	0.77	3.210	970.7	0.981
12	2.776	0.72	3.824	819.4	0.790

Fig. 5 Corrosion rates of X65 steel at different pressures in the 3.5 wt% NaCl solution after 14 days of immersion

Fig. 6 Corroded morphologies of X65 steel exposed to the 3.5 wt% NaCl solution at 0.1 MPa a, 12 MPa b for 14 days

Fig. 7 XRD spectra of the corrosion products obtained from the samples after 14 d of immersion in the 3.5 wt% NaCl solution at 0.1 MPa a, 12 MPa b

Fig. 8 Raman spectra of the corrosion products obtained from the samples after 14 d of immersion in the 3.5 wt% NaCl solution at 0.1 MPa a, 12 MPa b

Fig. 9 Macroscopic images of the corrosion products after 14 d of immersion in the 3.5 wt% NaCl solution at 0.1 MPa a, 12 MPa b

Fig. 10 The relative content of each component in the different corrosion products after 14 d of immersion in the 3.5 wt% NaCl solution

Fig. 11 Time dependence of Ecorr at 0.1 MPa, 12 MPa

References

[1]	Y. Yang, T. Zhang, Y. Shao, G. Meng, F. Wang, Corros. Sci. 52,2697(2010)
[2]	P. Traverso, E. Canepa, Ocean Eng. 87, 10(2014)
[3]	Z. Yang, B. Kan, J. Li, Y. Su, L. Qiao, A.A. Volinsky, Materials 10, 1307 (2017)
[4]	S.H. Xing, Y. Li, J.A. Wharton, W.J. Fan, G.Y. Liu, F. Zhang,X.D. Zhao, Mater. Corros. 68, 1123(2017)
[5]	R.E. Melchers, Corrosion 6, 895 (2005)
[6]	F. Reinhart, J. Jenkins, Port Hueneme, 1972)
[7]	R. Venkatesan, M.A. Venkatasamy, T.A. Bhaskaran, E.S. Dwarakadasa, M. Ravindran, Br. Corros. J. 37, 257(2002)
[8]	K. Ding, W. Guo, R. Qiu, J. Hou, L. Fan, L. Xu, J. Mater. Eng.Perform. 27, 4489(2018)
[9]	E. Canepa, R. Stifanese, L. Merotto, P. Traverso, Mar. Struct.59, 271(2018)
[10]	A.M. Beccaria, G. Poggi, M. Arfelli, G. Maitogno, Corros. Sci.34, 989(1993)
[11]	A.M. Beccaria, G. Poggi, G. Castello, Br. Corros. J. 30, 283(1995)
[12]	A.M. Beccaria, G. Poggi, D. Gingaud, P. Castello, Br. Corros.J. 29, 65(1994)
[13]	T. Zhang, Y. Yang, Y. Shao, G. Meng, F. Wang, Electrochim.Acta 54, 3915 (2009)
[14]	C. Zhang, Z.W. Zhang, L. Liu, Electrochim. Acta 210, 401 (2016)
[15]	Z.X. Yang, B. Kan, J.X. Li, Y.J. Su, L.J. Qiao, J. Electroanal.Chem. 822, 123(2018)
[16]	J. Dünnwald, A. Otto, Corros. Sci. 29, 1167(1989)
[17]	M.B. Leban, T. Kosec, Eng. Fail. Anal. 79, 940(2017)
[18]	M. Hanesch, Geophys. J. Int. 177, 941(2009)
[19]	O.N. Shebanov, P. Lazor, J. Raman Spectrosc. 34, 845(2003)
[20]	ASTM G1-03, Standard Practice for Preparing, Cleaning,Evaluating Corrosion Test Specimens. (ASTM International,West Conshohocken, 2003)
[21]	M.E. Orazem, B. Tribollet, Hoboken, 2008)
[22]	M. Stratmann, K. Hoffmann, Corros. Sci. 29, 1329(1989)
[23]	V. Lair, H. Antony, L. Legrand, A. Chausse, Corros. Sci. 48, 2050 (2006)
[24]	U.R. Evan, Nature 206, 980 (1965)
[25]	H. Sun, L. Liu, Y. Li, F. Wang, J. Electrochem. Soc. 160, C89(2013)