PSI - Issue 6

Svetlana Atroshenko et al. / Procedia Structural Integrity 6 (2017) 259–264 Author name / Structural Integrity Procedia 00 (2017) 000 – 000

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1. Introduction

The strength properties of magnesium alloys are of great interest, since they are the lightest structural materials with high specific strength. At the same time, it is known that the deformation treatment of magnesium and alloys based on it with a coarse-grained structure is hampered by the limited number of sliding systems characteristic of metals with hexagonal close-packed lattice. As a consequence, at present most of the complex shapes of magnesium alloys are produced by injection molding Volkova (2006), Mordike (2001), Raynor (1959). Common disadvantages of products obtained by this method are the heterogeneity inherent in the cast structure, the presence of defects in the form of pores, shells and, as a consequence, low strength. The study of the strength parameters and the nature of the destruction of such fairly new structural materials are of considerable interest. Complex studies of the structural magnesium alloy AZ31B was carried out. Investigations of the behavior of AZ31B alloy for quasi-static tension in conjunction with the evaluation of dissipation processes and determination of its dynamic strength under shock loading have been done. The initial samples were cut from the rolled sheet of the alloy AZ31B. The structure of the initial material is shown in Fig. 1. A very significant heterogeneity in the structure of the initial material is observed. There are a significant number of voids and microcracks. 2. Materials and experimental technique

Fig. 1. Microstructure of the initial magnesium samples.

The structure of alloys in the longitudinal direction is characterized by a pronounced geometric orientation, a line distribution of the strengthening phases. The alloy is characterized by a fine-grained structure with highly disperse hardening intermetallides. The results of measurements of the microhardness have a wide spread both in measurements in one sample and in different samples and amount is HV average = 107 MPa in the initial state. This is due to the substantial heterogeneity of the structure of the initial material. The results of grain size measurements also show a significant spread due to the heterogeneity of the initial material. The average grain size in the initial state was 14.6 μm (from 9 μm to 23 μm). The study of the behavior of the alloy in quasi-static tests was carried out on standard flat specimens of magnesium alloy AZ31B, with dimensions of the working part of 50 × 5 × (1.5 ÷ 3) mm on the universal test machine SHIMADZU AG-X with four capture speeds, which corresponded to a change in the strain rates 10 -2 ÷ 10 3 s -1 . Simultaneously, the thermal imaging camera ThermaCAM SC 300 recorded heat release during deformation Taylor et al. (1934). To investigate the strength properties of materials under shock loads, the phenomenon of electrical explosion of conductors was used at the installation with the following parameters: C = 6 μf, U ≤ 50kV, E ≤ 7.5 kJ, T s.c. = 11 μs Sud’enkov et al. (2017). The exploding AL foil was placed between the substrate plate and a ceramic waveguide with a diameter of  20 mm, in acoustic contact with which the sample was located. The temporal dependences of