Three types of oxygen precipitate morphologies at 1050 °C have been identified to be plate‐type, pyramidal, and polyhedral. This study was carried out using a set of slices with the same initial oxygen concentration but varying carbon concentrations. The morphology is shown to depend on carbon concentration and heat treatment. It is demonstrated that increasing carbon concentration tends to change the morphology from the plate to polyhedra and enhance the nucleation rate at low temperatures.