The Pitting Susceptibility Investigation of Passive Films Formed on X70, X80, and X100 Pipeline Steels by Electrochemical Noise and Mott-Schottky Measurements

Table 1

The chemical compositions of X70, X80, and X100 pipeline steels (wt. %).

Element	C	Si	Mn	S	P	Ni	Cr	Cu	Nb	Al	Ti	Mo	Fe
X70	0.045	0.26	1.48	0.001	0.0017	0.16	0.17	0.21	0.033	—	—	—	Bal.
X80	0.06	0.08	1.87	0.005	0.006	0.16	0.03	0.26	0.044	0.03	0.01	—	Bal.
X100	0.05	0.25	1.83	0.002	0.08	0.23	—	0.21	0.10	0.02	0.018	0.27	Bal.