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Methane formation through substrate-atmosphere interaction during 125 of Si containing steels

  • : Herbert Danninger1, Armineh Avakemian2, Christian Gierl-Mayer1, Magdalena Dlapka3, Matthias Grafinger3
  • : 1Technische Universitaet Wien, 2Voestalpine Stahl GmbH, 3MIBA Sinter Austria GmbH
  • : PDF Download
  • : 2014

Abstract

Decarburization during sintering of iron-carbon materials is mostly related to humidity in the atmosphere rather than formation of methane, although the latter is mentioned in particular in the older literature. This can be shown to advantage by thermoanalytical studies combined with mass spectrometry; masses 16 and 15 are hardly ever detected. However, if certain elements are present, methane formation can be clearly detected at least during the heating process, in defined temperature windows. In the present work it is shown that silicon as an alloy element strongly promotes carbon removal through CH4 formation when sintering in plain hydrogen atmosphere but much less in N2-H2 mixes. This process occurs during heating in a temperature interval between 600 and 800°C, being detectable, though less pronounced, in the same interval also during cooling. By intentional soaking at a temperature within this interval, the carbon content was lowered from an initial 2.0% carbon to 1.3%, 0.7% being removed as CH4, which implies that for sintering of complex alloyed steels, also methane formation should be taken into consideration.
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