COMPRESSION OF STEEL St3 BY A “WEAK” SHOCK WAVE

An experimental approach is presented that makes it possible to consider the pattern of wave interactions near the free surface of shock-loaded samples and their effect on the movement of the free surface. Shock wave experiments were conducted in which samples of steel St3 of different thicknesses were loaded with impactors made of the same material. The experiments were carried out on a light-gas “cannon” (working helium gas), the impactor was accelerated to speeds of 500 m/s; wave processes were diagnosed by recording the velocity of the free surface using a laser heterodyne interferometer. In the frontal section of the dependence of the velocity of the free surface of the sample on time, features in the form of “steps” are distinguished, which correspond to the exits to the free surface of an elastic wave (the first elastic precursor) propagating through the sample at the longitudinal speed of sound, and a re-reflected elastic wave from a plastic shock wave (the second elastic precursor). It is proposed to estimate the value of the velocity of the shock wave in the case of its elastic-plastic configuration by recording the time of the release of elastic precursors on the free surface of the sample. The shock adiabats of steel St3 are constructed, depending on the velocity of the shock wave on the mass velocity behind the wave front and the stress on the density of steel in the loading range up to a pressure of 13 GPa, corresponding to the beginning of the a-e phase transition in iron. The parameters of the equation of state of steel St3 in the Mi – Gruneisen form are determined, which make it possible to use this equation of state for numerical modeling of the behavior of matter in the low region of shock loading.