Aluminothermic Reduction Process Under Nitrogen Gas Pressure for Preparing High Nitrogen Austenitic Steels

Journal Article · Mon Apr 15 00:00:00 EDT 2019 · Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/S11663-018-1499-X· OSTI ID:22933663

Dorofeev, Gennady; Karev, Vladislav; Goncharov, Oleg; Kuzminykh, Eugeny; Sapegina, Irina; Lubnin, Alexey; Mokrushina, Marina; Lad’yanov, Vladimir ^[1]

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1. Ural Branch of the Russian Academy of Science, Udmurt Federal Research Centre (Russian Federation)

The aluminothermic reduction casting process under nitrogen gas pressure to make austenitic Cr-Mn-N (Ni-free) and Cr-N (Ni/Mn-free) high nitrogen stainless steels was investigated. Thermodynamic simulation of the redox reaction depending on process parameters was performed. As a result, the optimal ratio of aluminum to oxygen in the initial powder mixture to obtain the highest yield of metal product with minimal aluminum nitride contamination was predicted to be slightly greater than the stoichiometric ratio of 1.125. Microstructures of aluminothermic 26Cr1N and 23Cr9Mn1N steels, prepared taking into account the results of thermodynamic simulation, were investigated by X-ray diffraction, metallography, and transmission electron microscopy. The as-cast microstructure was a pseudo-pearlite (layered ferrite-nitride mixture) in 26Cr1N steel and a ferrite-austenite with signs of discontinuous austenite decomposition in 23Cr9Mn1N steel. After hot forging and subsequent water quenching from 1200 °C, the microstructure was fully austenitic in both steels. Tensile tests of quenched 23Cr9Mn1N steel showed a combination of high strength (ultimate strength of 1324 MPa) and ductility (elongation of 27 pct). The results illustrate that the aluminothermic casting process for producing high nitrogen steel is competitive with the commonly used methods, such as pressure electroslag remelting, both in terms of cost and mechanical properties of manufactured steel.

• OSTI ID: 22933663
• Journal Information: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science Journal Issue: 2 Vol. 50; ISSN 1073-5615; ISSN MTBSEO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM NITRIDES
AUSTENITE
AUSTENITIC STEELS
CASTING
DECOMPOSITION
DUCTILITY
ELONGATION
FERRITES
METALLOGRAPHY
MICROSTRUCTURE
NITROGEN
OXYGEN
PEARLITE
PRESSURE RANGE MEGA PA
QUENCHING
REDOX REACTIONS
STAINLESS STEELS
STOICHIOMETRY
THERMODYNAMIC MODEL
TRANSMISSION ELECTRON MICROSCOPY
ULTIMATE STRENGTH
WATER
X-RAY DIFFRACTION