Effects of Controlled Porosity on Shock Mitigation in Additively Manufactured 316L Stainless Steel
Taylor Sloop-Cabral, Georgia Institute of Technology
Additive manufacturing (AM) of stainless steels allows for tuning mechanical properties for unique functionalities. Stainless steel is a prime candidate material for use in a variety of applications due to its high strength, ductility, and corrosion resistance. AM fabricated stainless steel samples with intentional randomly-placed and controlled (strategically-located) pores are compared to AM fabricated samples with no porosity to determine the effects of intentional porosity on shock wave propagation and spall failure. The spall experiments were performed using an 80-mm gas gun and velocity profiles were obtained using multi-probe photon doppler velocimetry (PDV). Impacted samples were soft-recovered and analyzed post-shock using computerized tomography (CT) and electron backscatter diffraction to investigate void nucleation and coalescence in relation to pore locations. We observed that the number and size of the pre-existing pores affects shock wave propagation, up to and including spall mitigation. For the samples with random porosity as well as the strategically placed 500 µm pore in the sample center, spall damage is observed away from the pores. However, with the 350 and 200 µm pores, stress dissipation is not sufficient to prevent void growth and coalescence, leading to spall failure in the vicinity of the pores in these controlled porosity samples.
Abstract Author(s): Taylor Sloop, Kevin Lamb, Katie Koube, Elias Winterscheidt, Sudarsanam Babu, Josh Kacher, Naresh Thadhani