Chemical reactions during sintering of PM steel compacts as a function of the alloying route

ABSTRACT

Due to their large specific surface, powders and powder compacts typically contain significant amounts of oxygen which has to be removed in the early stages of sintering. In the present study, it is shown that the homogeneity/heterogeneity of the oxygen affinity within the compact, which depends on the alloying route chosen, strongly affects the de-oxidation process. For several types of alloy steels, it is shown that systems alloyed through the mixing or master alloy route and containing elements with widely varying oxygen affinity exhibit oxygen transfer reactions through the internal gas phase. For pre-alloyed grades, in which the oxygen affinity is homogeneous, i.e. consistent between the powder particles, transfer reactions occur rather within the metallic particles themselves. In any case, the sintering temperature should be selected such as to grant reduction also of the most stable oxides contained.

Special block from the conference RoPM2017 guest edited by Ionel Chicinas, Technical University, Cluj-Napoca.

KEYWORDS:

• Sintered steels
• sintering
• chemical reactions
• oxygen

Acknowledgement

The authors want to acknowledge the financial support from the European Union through a Marie Sklodowska-Curie scholarship (Grant agreement PIEF-GA-2013-625556) to one of the authors (R. de Oro Calderon).

Disclosure Statement

No potential conflict of interest was reported by the authors.

ORCID

Herbert Danninger http://orcid.org/0000-0002-7205-9058

Raquel de Oro Calderon http://orcid.org/0000-0001-7341-6267

Christian Gierl-Mayer http://orcid.org/0000-0001-8944-3534

Additional information

Funding

The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme FP7/2007-2013/ under REA grant agreement n° 625556. The support from the European Commission through the work program People FP7-PEOPLE-2013-IEF is very gratefully acknowledged.