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:

Prof. A.Milenin

Dr. inż. P.Kustra

Prof. M.Pietrzyk

 

Poster

Project in media

5-page report (in Polish)

 

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

[5] D.S. SVYETLICHNYY, P. KUSTRA, A. MILENIN  Modeling with FCA-based model of microstructure evolution of MgCa08 alloy during drawing of thin wire in heated die, Archives of Metallurgy and Materials, 60, 20154, 2721–2727.