Influence of the mechanical alloying process on the sintering behaviour of astaloy CrM powder mixture with silicon carbide addition

Abstract

Due to an excellent combination of toughness and strength, bainitic-austenitic dual phase steels with silicon addition have many applications in the industry. However, silicon has a high affinity to oxygen and, therefore, its introduction to the alloy is problematic during the classical sintering processes of mixing powders. Mechanical alloying (MA) offers one of the most attractive alternatives to the introduction of silicon to Astaloy CrM powders.The aim of the present study was to determine the influence of the MA process on changes in particle size distribution, work hardening and sintering behaviour of the investigated powder mixture -Astaloy CrM powder with the addition of 2 wt.% stearic acid and 2 wt.% silicon carbide alloyed under different conditions. The practical aspect of this study was to develop and apply a common and inexpensive method of die-pressing to compact a powder mixture prepared by the MA process.Keywords: mechanical alloying, Astaloy CrM, silicon carbide, dilatometric analysis, mass spectrometry analysis Dwufazowe stale bainityczno-austenityczne ze względu na swoje właściwości wytrzymałościowe i plastyczne mają coraz szersze zastosowanie w przemyśle. Jednakże wprowadzanie do składu mieszanek dodatku krzemu nastręcza wiele problemów technologicznych podczas klasycznego spiekania materiałów proszkowych m.in. poprzez duże powinowactwo tego pierwiastku do tlenu. Proces mechanicznego stopowania oferuje jedno z alternatywnych rozwiązań wprowadzenia krzemu do niskostopowych proszków Astaloy CrM.W pracy przedstawiono wyniki badań wpływu procesu mechanicznego stopowania na zmiany wielkości cząstek proszku, ich utwardzenie oraz efekty zachodzące podczas spiekania mieszanek: Astaloy CrM z dodatkiem 2% wg kwasu stearynowego i 2% wg węglika krzemu, wytworzonych w różnych warunkach stopowania. Praktycznym aspektem przeprowadzonych badań było uzyskanie mieszanek po procesie stopowania mechanicznego nadających się do formowania matrycowego, jako najtańszej i najbardziej rozpowszechnionej metody kształtowania wyrobów proszkowych.

Dilatometric study of low-alloy steels with silicon carbide addition

“…Based on all of the obtained results, it may be observed that using an inert atmosphere with 10 % H 2 is enough to obtain the same results as after sintering in a reducing atmosphere of hydrogen. These observations are in accordance with results obtained in previous research [18].…”

Spark Plasma Sintering of Low Alloy Steel Modified with Silicon Carbide

“…Therefore, the mechanical alloying parameters (primarily the ratio of powder mass to ball mass, milling time, size of grinding balls and rotary speed) had a significant effect on the final size of the particles obtained after the alloying process. The obtained results are in full agreement with the results obtained for similar mechanical alloyed compositions which are characterized by the same alloying model -a ductile/brittle component system [21,22].…”

Application of a device used for observation of controlled thermal processes in a furnace

“…A change or failure to follow them usually results in an abnormality of the constructed product. In powder metallurgy two of the most important technological parameters are adequate atmosphere and sintering temperature [17][18][19][20][21].…”