Reactions between ferrous powder compacts and atmospheres during sintering – an overview

ABSTRACT

This overview paper describes the interaction of powder metallurgical iron-base alloys with the atmosphere during sintering. The methods of thermal analysis serve to clarify the processes that take place especially during the heating stage of the sintering cycle. After a discussion of the physical and chemical fundamentals of the sintering process, the methods of thermal analysis are explained. The differences between plain iron and alloyed systems are discussed in detail. Classical PM low alloy steels with alloying elements, such as Cu, Ni and Mo, react in a similar way as unalloyed carbon steels. The situation changes dramatically, when oxygen sensitive elements as chromium, manganese and even more silicon come into play. The removal of the surface oxygen is much more crucial, and there are several competing reactions, which have to be considered when these systems should be sintered in industrial scale to reach the desired mechanical and dimensional properties.

KEYWORDS:

• Sintered steels
• atmospheres
• thermal analysis
• degassing
• alloy elements

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes on contributors

Christian Gierl-Mayer studied Technical Chemistry at TU Wien, Vienna Austria. He made his Master Degree in Inorganic Chemistry in 1996. He got his PhD in 2000 from TU Wien for ‘Production of PM structural parts by optimised sintering‘. After three years as scientist in private research institute (ofi-Austrian Institute for Chemistry and Technology) he became senior scientist at TU Wien, Institute for Chemical Technologies and Analytics (2003). 2017 he was promoted Associate professor and 2019 after his habilitation in powder metallurgy he became Associate Professor for metallic sintered materials. He is currently leading the research group ‘Powder metallurgy’ at the above mentioned Institute. He is currently leading the research group ‘Powder metallurgy’ at the above mentioned Institute.