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The industrial production of high manganese steel melts with approx. 10-30 wt% Mn makes high demands on the utilized Mn-bearing alloying agents in terms of chemical composition and cost-efficiency. Conventional Mn-bearing alloying agents are reviewed in this regard. A modified process route has been conceived for pyrometallurgical winning of special silicomanganese grades tailored for high manganese steelmaking. For each individual process step, namely manganese slag production, silicomanganese production, and optional desiliconization of silicomanganese, results of lab-scale experiments are discussed.

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Abstract:The topic of the present experiments are transition metal diboride coatings of composition (Ti 0.49 W 0.51 )B 2 and (Ti 0.44 W 0.30 Cr 0.26 )B 2 . The coatings were deposited on steel substrates using dc magnetron sputtering. We investigated how annealing in argon at elevated temperatures modifies microstructure. The as-deposited films are amorphous. Annealing between 700 and 1100 °C results in the formation of nano-crystalline precipitates with average grain diameters of about 10-50 nm. A TiC phase (Fm-3m; a ≈ 4.3 Å) is observed as the dominating precipitate phase. In addition, small amounts (10%-20%) of a Cr 23 C 6 phase (Fm-3m; a ≈ 10.6 Å) are observed. In contrast to literature data on the same coatings deposited on silicon substrates, the formation of boride precipitate phases is strongly suppressed here. From investigations with X-ray diffractometry, electron microscopy and secondary ion mass spectrometry we conclude that the nanostructure of the coatings is formed by reactive phase formation of the boride coating with the carbon containing steel substrate.