Effectiveness of reducing agents during sintering of Cr-prealloyed PM steels. (September 2014)

• Record Type: Journal Article
• Authors: Hryha, E.; Nyborg, L.
• Is Part Of: Powder metallurgy. Volume 57:Number 4(2014)
• Page Start: 245
• Page End: 250
• Publication Date: 2014-09
• Subjects: Powder metallurgy -- Periodicals; 671.3705
• DOI: 10.1179/0032589914Z.000000000192
• Languages: English
• ISSNs: 0032-5899

Abstract

<abstract> <title> <x content-type="archive" xml:space="preserve">Abstract</x> </title> <p>Development of strong inter-particle necks requires successful removal of surface oxides, present on the powder particles, during the initial stages of sintering. In the case of water-atomised powder prealloyed with chromium, the surface oxide consists mainly of an iron oxide layer with some more stable fine particulate oxides. The formation of sufficiently strong inter-particle necks requires as a minimum full removal of the iron surface oxide layer. This can be achieved by gaseous reducing agents (e.g. H₂, CO or a mixture of both) or by carbon, typically admixed in the form of graphite. The reducing power of various sintering atmospheres (active gas content ≤10 vol.-%) and their combined effect with graphite has been investigated by a thermal analysis technique. Results indicate that a combination of a dry hydrogen-containing atmosphere and fine graphite allows successful sintering of chromium alloyed PM steels.</p> </abstract>