High Strain Rate Yielding of Additive Manufacturing Inconel 625 by Selective Laser Melting

Nickel-based alloy Inconel 625, produced by the selective laser melting method, was studied experimentally for its mechanical performance under strain rate loading using Hopkinson bars. Both compression and tensile tests were carried out, with the former also being conducted at 500 °C. The strain rate was in the range of 300 to 3500 s^-1 at ambient temperature, and 1200 to 3500 s^-1 at the elevated temperature, respectively, for compression tests, and 900 to 2400 s^-1 for tensile tests. Results show that the alloy has a strong rate sensitivity with the dynamic yield stress at 3500 s^-1, almost doubling the quasistatic value. The test results also show that, even though the temperature elevation leads to material softening, the strain rate effect is still evidential with the dynamic compressive yield stress at the rate 10³ s^-1 and 500 °C still being higher than the quasistatic one at ambient temperature. It is also observed that dynamic tensile strengths are generally higher than those of compressive ones at room temperature.