Tilen Balaško (Author), Maja Vončina (Author), Jaka Burja (Author), Barbara Šetina (Author), Jože Medved (Author)

Abstract

The high-temperature oxidation of hot-work tool steel AISI H11 was studied. The high-temperature oxidation was investigated in two conditions, the soft annealed condition, and the hardened and tempered condition. First, calculations of the compositions of the oxide layers formed were carried out using the CALPHAD method. The samples were oxidised in a chamber furnace and in a simultaneous thermal analysis instrument, for 100 h in the temperature range between 400 °C and 700 °C. The first samples were used for metallographic (optical microscopy and scanning electron microscopy) and X-ray diffraction analysis of the formed oxide layers, and the second ones for the analysis of the oxidation kinetics by thermogravimetric analysis. Equations describing the high-temperature oxidation kinetics were derived. The kinetics can be described by three mathematical functions, namely: exponential, parabolic, and cubic. However, which function best describes the kinetics depends on the oxidation temperature and the thermal condition of the steel. Hardened and tempered samples have been shown to oxidise less, resulting in a slower oxidation rate. The oxide layers consist of three sublayers, the inner one being spinel-like oxide (Fe, Cr)$_3$O$_4$, the middle one a mixture of magnetite and hematite and the outer one of hematite. At 700 °C there is also some wüstite in the inner oxide sublayer of the soft annealed sample.

Keywords

high-temperature oxidation;AISI H11 tool steel;thermogravimetry;CALPHAD;kinetics;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL NTF - Faculty of Natural Sciences and Engineering
UDC: 669
COBISS: 62092547 Link will open in a new window
ISSN: 2075-4701
Views: 138
Downloads: 38
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Other data

Type (COBISS): Article
Pages: str. 1-27
Volume: ǂVol. ǂ11
Issue: ǂno. ǂ5
Chronology: 2021
DOI: 10.3390/met11050758
ID: 14759901