On constitutive modelling of the compaction and sintering of cemented carbides
1998 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]
The common manufacturing procedure for components of cemented carbide is a closed die cold compaction of a powder and a subsequent sintering of the compact to full density and strength.
Major problems with the manufacturing process are the possible fracturing on ejection from the tooling and the distortion in the final shape. It is beneficial to perform the design iterations in the form of computer simulations, provided such simulations predict at least the final shape with good accuracy. This thesis concerns the development of computer simulation tools for both the compaction and the sintering.
A constitutive model for the compaction based on elasto-plasticity has been developed. The model has a compactness tensor that measures the directionality of the deformation history and a two-dimensional hardening parameter set. The model represents the deformation induced anisotropy in the form ofa kinematic hardening combined with an isotropic hardening, and uses a flow rule that emanates from a non-associated flow potential.
Furthermore, a continuum model of the sintering with and without loading has been developed, based on a micromechanical model of the sintering without loading. The model is visco-elastic with the capillary forces represented bya sintering stress. The model parameters evolve with temperature, relative density and rate of temperature. The author presented a rationale for deciding, in which mechanism the rate of temperature influence belongs.
The models were implemented in the explicit FE-program LS-DYNA2D and verified against several experimental compaction and sintering tests. Finally, the models have been verified by the simulation of the complete compaction and sintering process of an industrial tool piece. The agreement between simulation and measurement in final shape is good. The convergence of the simulation concept is also demonstrated.
Place, publisher, year, edition, pages
Linköping: Linköping University , 1998. , p. 22
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 521
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:liu:diva-181557Libris ID: 7624047ISBN: 9172191740 (print)OAI: oai:DiVA.org:liu-181557DiVA, id: diva2:1615981
Public defence
1998-04-23, Planck, Fysikhuset, Linköpings universitet, Linköping, 10:15
Opponent
Note
All or some of the partial works included in the dissertation are not registered in DIVA and therefore not linked in this post.
2021-12-012021-12-012021-12-01Bibliographically approved