Development of multi- scale model
of recrystallization, that occurs in fine wires from biocompatible Mg alloys
during drawing at elevated temperature for diameters of wires, comparable with
the size of grains of microstructure
National Science Centre of Poland,
project no. 2012/05/B/ST8/01797
Principal
participants:
Dr. inż.
P.Kustra
1.
Brief description
The problem dealt with in the
project is related to obtaining of thin (diameter of about 0.05 mm) wire of biocompatible
magnesium alloys. Such wires can be used as resorbed surgical sutures. The
problem, however, lies in the low ductility of examined alloys. While drawing a
wire diameter of 1.0 mm to 0.05 mm, the wire extends 400 times (from 1 meter of
billet it will get 400 meters of wire). There is a need to develop a method to
increase the plasticity of Mg alloys during drawing process. The second problem
is that the wire with diameter of 0.05 mm is comparable to the dimensions of
the grains of the material. It is necessary to develop a solution, which takes
into account macro and micro scales of the processes. The method proposed in
the project is implemented by way of pulling in the heated dies. The basis of
the process is to carry out drawing in conditions in which recrystallization
occurs. This allows for restoration of plasticity and multi-pass drawing
without intermediate annealing. Controlling of recrystallization process after
every pass using experimental method, development of multi-scale simulation of
recrystallization and optimization of the process are the methods to develop
the optimal process parameters. In the project a complex numerical model of
drawing process with multi-scale model of recrystallization was presented. The
results of simulations have been compared with experimental data obtained using
the device of our own design. The wire with a diameter of 0.05 mm has a high
strength and plastic characteristics, allows formation of multiple surgical
knots.
2. Research project
objectives/ Research hypothesis
The proposed project is dedicated
to fundamental theoretical and experimental research of recrystallization
phenomenon in new generation of Mg alloy, which can be applied as material for
soluble implants with dimension comparable to grain size.
The work includes the issue of
development of a new method of producing of thin wires with diameters 0.1mm and
smaller of Mg alloys with improved biocompatibility (eg
MgCa0.8, Ax30, AL36). The goal of this project is understanding the phenomena occurring
in the deformed microstructure of magnesium alloys, in particular the recrystallization
process and the renewal of plasticity.
A following hypothesis was proposed:
if when one of a product dimensions is comparable to elements of microstructure
(e.g. wire with diameter bellow 0.1mm), there exist deformation conditions and
temperature conditions, which in future allow for multi-pass plastic
deformation with local heating in deformation zone (e.g. drawing process with
heated dies) without inter-pass annealing.
3. Research project
methodology
In order to proof hypothesis
the theoretical research in micro-scale by cellular automata method are proposed
and in macro-scale by known equations based on dislocation theory. The physical
simulation of deformation in GLEEBLE 3800, deformation in drawing devices
design by applicants and advanced metallographic analysis are proposed as
experimental studies for verification purpose. Such range of studies allows to
describe a fundamental recrystallization phenomenon, which occurs in products
with dimensions comparable to microstructure elements made from new generation
of magnesium alloys with application to soluble implants.
4. Expected impact of the
research project on the development of science, civilization and society
Proposed in the project studies
allow to describe a fundamental recrystallization phenomenon, which occurs in
products with dimensions comparable to microstructure elements made from new
generation of magnesium alloys with application to soluble implants. Describing
of this phenomena will be important to support the design and manufacture process
of micro-implants of analyzed biocompatible magnesium alloys.
5. Publications
[1] A.
MILENIN, P. KUSTRA, D. BYRSKA-WÓJCIK, FEM-BEM code for the multiscale modeling and
computer aided design of wire drawing technology for magnesium alloys, Advanced
Engineering Materials, 16, 2014, 202–210.
[2] A. MILENIN, P. KUSTRA, M. PIETRZYK, Physical and numerical modelling of
wire drawing process of Mg alloys in heated dies accounting for recrystallization,
Key Engineering Materials, 622-623, 2014,
651–658.
[3] A. MILENIN, P. KUSTRA, M. KOPERNIK, The development and validation of a meso-scale numerical model of fracture in the biocompatible
magnesium alloys during drawing of hyperfine wire, Proc. Conf. Computational Fluid
and Solid Mechanics, Massachusetts Institute of Technology, Cambridge, USA,
2013
[4] A. MILENIN
, M. GZYL, T. REC , B. PLONKA COMPUTER AIDED DESIGN OF WIRES EXTRUSION
FROM BIOCOMPATIBLE Mg-Ca MAGNESIUM ALLOY, Archives of Metallurgy and
Materials, 59, 2014, 551-556