Oxide Reduction Processes, Microstructure and Properties of Sintered Chromium Pre-Alloyed Steel

Abstract:

The reduction processes during the sintering of Fe-3Cr-0.5Mo+0.5C pre-alloyed powder using continuous monitoring of exhaust gas composition (CO, CO₂, H₂O) have been identified and interpreted in relation to the density (6.5-7.4 g/cm³), sintering temperature (1120 and 1200°C), heating and cooling rates (10 and 50°C/min) and type of sintering atmosphere (10%H₂-N₂, N₂), respectively. The progress in reduction processes was evaluated by the change in C and O contents, and fracture strength values as well. The results were compared with metallographic study of microstructure and fractographic observations of fracture surfaces. Higher sintering temperature (1200°C) and low density (<7.0 g/cm³) resulted in a relative decrease in oxygen content by more than 80%. Higher cooling rate (50°C/min) eliminates re-oxidation during cooling. High density of 7.4 g/cm³, achieved by double pressing, indicated to have a negative effect on reduction processes due to restricted replenishment of the “microclimate” atmosphere with the processing gas. Higher O₂ content causes weakening of interfaces with residual oxides.

• Periodical: Materials Science Forum (Volume 782)
• Pages: 487-490
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.782.487
• Online since: April 2014
• Authors: Monika Hrubovčáková, Eva Dudrová, Margita Kabátová
• Keywords: Cr-Alloyed Steel Powder, Exhaust Gas Composition, Microstructure, Oxide Reduction Processes, Sintering, Strength Properties

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DOI: 10.4028/www.scientific.net/msf.426-432.4337

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