The multi-scale numerical and experimental analysis of cold wire drawing for hardly deformable biocompatible magnesium alloy

Andrzej Milenin , Piotr Kustra, Dorota Byrska-Wójcik

AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, Poland.

DOI:

https://doi.org/10.7494/cmms.2013.2.0436

Abstract:

The problem of determination the drawing schedule of the cold drawing of thin (less than 0.1 mm) wire from the hardly deformable magnesium alloy Ax30 with the aid of the multi-scale mathematical model is examined in the paper. The special feature of the alloy Ax30 is the mechanism of fracture on the grain boundaries. It is experimentally proven that the microscopic cracks during the tension tests occurs long before the complete fracture of samples. The state of metal, which directly precedes the appearance of these microscopic cracks, is proposed to consider it as optimum from the point of view of the restoration of plasticity with the aid of the annealing. The simulation of this state in the wire drawing process and development on this basis regimes of wire drawing is the purpose of paper. Solution of problem required the development of the fracture model of alloy in the micro scale, identification of the fracture model and its implementation into the FEM model of wire drawing. Two schedules of wire drawing are examined. The first of them is according to the results of simulation allowed the appearance of microscopic cracks. The second regime was designed so that the microscopic cracks would not appear during wire drawing. Experimental verification is executed in laboratory conditions on the specially developed device. The annealing was carried out before each passage. The initial diameter of billet was 0.1 mm. In the first regime it was possible to realize only 2-3 passages, after which the fracture of wire occurred. The cracks on the grain boundaries were observed in this case on the surface of wire. The second regime made it possible to carry out 7 passages without the fracture, the obtained wire with a diameter of 0.075 mm did not contain surface defects, it had high plastic characteristics and allowed further wire drawing. Thus, the validation of the developed multi-scale model is executed for two principally different conditions of deformation.

Cite as:

Milenin, A., Kustra, P., & Byrska-Wójcik, D. (2013). The multi-scale numerical and experimental analysis of cold wire drawing for hardly deformable biocompatible magnesium alloy. Computer Methods in Materials Science, 13(2), 238 – 244. https://doi.org/10.7494/cmms.2013.2.0436

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