An acoustic method of investigating the titanium alloys construction materials

M. Lyakhovitskiy 1, V. Roshchupkin1, M. Pokrasin1 and N. Minina1

1Baikov Institute of Metallurgy and Materials Science, RAS, Moscow, Russia

Keywords: acoustic and dilatometric properties, density and Young's modulus
property: acoustic and dilatometric properties
material: titanium alloys

The wide application of titanium and its alloys in the technology requires comprehensive examination of their physical mechanical properties over a wide range of temperatures. The number of physical properties, which carry extensive information about the structural and physical mechanical properties in the structural metallic materials, includes dilatometric and acoustic properties, in particular the speed of propagation of sound, which give the possibility of the immediate determination of Young's modulus of these materials. In the present work are represented the results of acoustic and dilatometric studies of VT5, VT20, VT23 alloys (as the primary experimental material), and also the calculated on their basis values of density and Young's modulus in the range of temperatures from the room to 1000°C. Furthermore, the acoustic emission (AE) of these alloys is investigated in the process of their heating, annealing and aging for samples in initial, annealed and thermally reinforced states. Special attention in this case was paid to the temperature range of the polymorphous transformation of alloys. It is shown that AE appears during the annealing, aging and in process of the polymorphous transformation of titanium alloys. In this case the strengthening of AE in all samples with their heating was observed precisely in the temperature range of polymorphous transformation. Furthermore, it is discovered, that AE substantially depends on the structural state of VT23 alloy. This makes it possible to examine the method of the acoustic emission as the sensitive tool of analysis of changes in structures of two-phase titanium α+β - alloys at their heat treatment and to propose it as basis for the standard procedure of quality control of articles from them. Moreover, for this control it suffices to measure the acoustic emission in the process of heating the finished article to 400°C, that it does not exceed the limits of operating temperatures of the majority of titanium alloys. The work is supported by RFBR (RU) 09-08-00535a; 09-08-00563a.

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