Abstract:
It is shown that the cylindrical iron and carbon–steel specimens of diameters 1.5 and 3 mm ignite in oxygen at the moment the oxide film loses its protective properties, supposedly, as a result of melting of its main component (FeO) at 1644 K. The ignition temperature does not depend on the oxygen pressure (in the range 0.2–20 MPa). The ignition is preceded by substantial (about 100 K) self–heating of a specimen owing to the heat released upon oxidation of the metal. A carbon–steel foil ignites in oxygen (0.14–0.6 MPa) according to the Semenov–Frank–Kamenetskii mechanism at an initial surface temperature not lower than 1233 K.