(a)
(b)
(c)

Figure 6: SEM images of three types of inclusions after initiation and propagation of pitting corrosion in X70 steel: (a) Type A (particles of (Al, Ca)O and (Mn,Ca)S); (b) Type B ((Al,Ca)O), and (c) Type C ((Mn, Ca)S). Steel was immersed in 0.1 mol/L NaCl and 0.5 mol/L NaHCO3 solutions at 25°C for times indicated in figure [50].