Spall Strength of 09CrNi2MoCu Steel Manufactured by Hot Rolling and Direct Laser Deposition in the Submicrosecond Loading Range

Strength measurement results are reported for hot-rolled cast cold-resistant structural alloy steel 09CrNi2MoCu subjected to shock compression up to 15.5 GPa within the strain rate range of 10⁵–10⁶ s^–1. Specimens fabricated by direct laser deposition were used to study the effect of the deposition direction and shock compression amplitude on the Hugoniot elastic limit and critical stresses during spall fracture. The strength characteristics were determined by analyzing the full waveform data recorded during loading by a VISAR laser Doppler velocity interferometer. It was found that the spall strength of the cast steel specimens is almost independent of the shock compression pressure, but strongly depends on the strain rate before spalling. The spall strength of the additively manufactured specimens is slightly lower than that of the hot-rolled cast steel specimens and does not depend on the deposition direction. The α ↔ ε phase transformation expected at 13 GPa was not observed in experiments on cast steel 09CrNi2MoCu with the maximum shock compression pressure.