Investigations of the diverse corrosion products on steel in a hydrogen sulfide environment

• Diverse corrosion products on steel are investigated in H2S environment.
• The sequence of the main corrosion products is mackinawite + cubic FeS → troilite.
• The large single beam-shaped troilite has a growth pattern along the c axis.
• The flower-like troilite develops from beam- or hexagonal wire-shaped grains.
• The corresponding crystal structure and morphology of the products are provided.

The corrosion products of carbon steel in aqueous H2S environment are investigated. The products, which include mackinawite, cubic FeS, troilite, and pyrite, are characterized through their shapes, chemical compositions and crystal structures. Mackinawite appears with a flake shape. Cubic FeS has a perfect/truncated octahedral shape, and pyrite is framboid-shaped. Flower-shaped troilite is developed from beam- or hexagonal wire-shaped grains by electrostatic interactions along a certain lattice plane. The large single beam-shaped troilite has a growth pattern along the c axis. The corresponding crystal structure and micro-morphology of the corrosion products are provided, and the three-dimensional models of them are generated.