High-Temperature Oxidation Behaviour of AISI H11 Tool Steel

The high-temperature oxidation of hot-work tool steel AISI H11 was studied. investigated in two conditions, the soft annealed condition, and hardened tempered condition. First, calculations compositions oxide layers formed were carried out using CALPHAD method. samples oxidised a chamber furnace simultaneous thermal analysis instrument, for 100 h temperature range between 400 °C 700 °C. first used metallographic (optical microscopy scanning electron microscopy) X-ray diffraction layers, second ones kinetics by thermogravimetric analysis. Equations describing derived. can be described three mathematical functions, namely: exponential, parabolic, cubic. However, which function best describes depends on condition steel. Hardened have been shown to oxidise less, resulting slower rate. consist sublayers, inner one being spinel-like (Fe, Cr)3O4, middle mixture magnetite hematite outer hematite. At there is also some wüstite sublayer sample.