Surface Relief Accompanying Bainitic Transformation in an Fe–C–Si–Mn Alloy Studied by Scanning Tunneling Microscopy

Abstract

Surface relief effect accompanying bainitic transformation in an Fe–C–Si–Mn alloy has been investigated by scanning tunneling microscopy (STM). It was discovered that a lower bainite subunit in an Fe–C–Si–Mn alloy is composed of sub-subunits, whose surface reliefs are tent-shaped, i.e. of a non-invariant plane strain (IPS) type, which is inconsistent with shear mechanism. The sub-subunit is idiomorphic, the height of its relief is 60–140 nm, and its maximum shape deformation is ca. 0.23. Multi-layer structure of bainite and effect of composition in steels on the ultrafine structure of lower bainite can be interpreted by the sympathetic nucleation-ledgewise growth mechanism.