compounds after 40 days of immersion is higher than
that of corrosion compounds after 18 days of immersion. XRD
graphs of tin-containing steel show the differentia that the relative
content of Fe3O4 in Fig. 12(b) is higher than that of Fig. 12(a). As is
well known, the corrosion resistant grade of iron oxide–hydroxide is
β-FeOOH b γ-FeOOH b α-FeOOH, and the metastable γ-FeOOH will
transform to steady Fe3O4 as corrosion period went. This shows that
the content of corrosion resistant substance of tin-containing steel's
rust layer is higher than that of tin-free steel's rust layer.