PSI - Issue 28

S.A. Atroshenko et al. / Procedia Structural Integrity 28 (2020) 101–105 Author name / Structural Integrity Procedia 00 (2019) 000–000

102

2

formation of structure and properties during various heat treatment and alloying. In this regard, the study of the formation and evolution of structures of titanium alloys during high-speed impact is also important for the development of technological processes for their manufacture and for the development of dynamic fracture mechanics as a whole. This work is devoted to a detailed study of the structure of 3M titanium alloy, which is formed during the penetration of a target from this alloy by an irregularly shaped striker at a collision velocity of ~ 2 km/s similar conditions described in Kolpakov et al. (2016). It was previously shown Savenkov et al. (2018) that the shock loading of samples from this alloy as a whole led to their hardening, no other features were noted. 2. Material and experimental technique A general view of a punched target 11 mm thick is shown in fig. 1. The initial alloy structure is characterized by basket weaving typical of thermally unstrengthened α-alloys of the martensitic class. Such a structure, as a rule, corresponds to the optimal complex of long-term heat resistance, creep limit while maintaining a high level of strength properties as shown in Belov et al. (1992). No signs of deformation such as slip bands and twins were found.

Fig. 1. General view of a punched target.

The main physical properties of the material under study as well as the standard mechanical properties determined on samples from rods from which the targets for research were subsequently made, are given in Table. 1.

Table 1. Material Properties.

Volumetric

σ 0,2 , GPa σ b , GPa δ 5 , % ψ, % HV, GPa

Poisson's ratio Young's modulus, GPa

Density, ρ kg/m 3

speed of sound c 0 , m/s

4540

0.3

112

4530

660±10 715±10 22±1

36±1 2.0±0.26

The structure was studied using an Axio – Observer Z1 M optical microscope in a bright field and in contrast with a C-DIC . The microhardness of the titanium alloy was determined on a SHIMADZU microhardness device of the HMV-G series (according to the Vickers method) at a load of 0.49 N. The speed of penetration ( v ) of the striker into the obstacle at the specified initial impact speeds varies according to the law Khantuleva et al. (2017) v=v 0 exp(-kx) ; where v 0 is the initial impact velocity; k=3C x /8rk ; C x - drag coefficient; r - impactor radius . For general reasons, you can take k ≈0.2 mm -1 .