Failure analysis of stellite dies for brass extrusion: The effect of aging

Bourithis, L; Gontzes, V; Papadimitriou, GD

dc.contributor.author	Bourithis, L	en
dc.contributor.author	Gontzes, V	en
dc.contributor.author	Papadimitriou, GD	en
dc.date.accessioned	2014-03-01T01:26:21Z
dc.date.available	2014-03-01T01:26:21Z
dc.date.issued	2007	en
dc.identifier.issn	09240136	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18028
dc.subject	Aging	en
dc.subject	Brass	en
dc.subject	Cobalt alloys	en
dc.subject	Extrusion	en
dc.subject	Fatigue	en
dc.subject	Stellite	en
dc.subject.other	Aging of materials	en
dc.subject.other	Brass	en
dc.subject.other	Cobalt alloys	en
dc.subject.other	Cracks	en
dc.subject.other	Cyclic loads	en
dc.subject.other	Dies	en
dc.subject.other	Failure analysis	en
dc.subject.other	Metal extrusion	en
dc.subject.other	Precipitation (chemical)	en
dc.subject.other	Brass extrusion	en
dc.subject.other	Brittle carbides	en
dc.subject.other	Ductile cobalt dendrites	en
dc.subject.other	Stellite	en
dc.title	Failure analysis of stellite dies for brass extrusion: The effect of aging	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.jmatprotec.2006.09.018	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.jmatprotec.2006.09.018	en
heal.publicationDate	2007	en
heal.abstract	Improving the performance of the extrusion tools and predicting their life postulates knowledge of their failure mechanisms. In this work, actual failure cases of brass extrusion dies made from stellite 4B are presented and their mechanisms are studied. It is found that exposed parts of the die suffer from cyclic loading which, in combination with manufacturing defects and design imperfections, promote the initiation of fatigue cracks. Aging during service of stellite 4B inserts reduces die life due to the formation of a network of brittle carbides surrounding the ductile cobalt dendrites. During extrusion, the M7C3 carbide dissolves in the cobalt matrix leading to precipitation of new M23C6 and η-carbide types. This occurs at relatively low working temperatures, in the range of 600-650 °C, instead of 850-1100 °C as referred in the resent literature, and is probably assisted by high stresses prevailing during the extrusion process. © 2006 Elsevier B.V. All rights reserved.	en
heal.journalName	Journal of Materials Processing Technology	en
dc.identifier.doi	10.1016/j.jmatprotec.2006.09.018	en
dc.identifier.volume	182	en
dc.identifier.issue	1-3	en
dc.identifier.spage	608	en
dc.identifier.epage	614	en