Composition: Carbon steel (0.35%C, hypoeutectoid).

Processing: Hot rolled.

Etching: 15-30 s immersion in 2% nital.

This is the same steel as X19, but here the longitudinal view is presented (along the rolling direction). For hypoeutectoid steels, the rolling process, either in the biphasic α + γ field or the monophasic one (γ), produces a banded structure of ferrite and pearlite. Rolling in the biphasic field aligns the grains of α and γ in alternating bands. Then, γ transforms to pearlite during the cooling stage. On the other hand, rolling in the γ field should not produce this banded structure. However, the MnS inclusions get elongated during deformation, thus favouring the formation of ferrite bands at their interphase with the austenite and pearlite at a further distance. This banded structure does not dissappear with a conventional annealing treatment.

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