Effect of compressive strain rate on the deformation behaviour of austenitic stainless steel foam produced by space holder technique

Abstract

316L austenitic stainless steel foam (ASSF) with 55–81% porosities was made by P/M route using urea as space holder. The cold compacted at 500 MPa pressure and sintered at 1200 °C for 60 min. Microstructure, cell size, cell walls thickness and micro-hardness were evaluated. Twins boundaries are visible in cell wall regions. XRD, FESEM, and EDX analysis proved that no residue of space holder particles remained in the sintered foam samples. The compressive deformation behaviour of sintered foam samples are studied under three different strain rate (0.001, 0.01, and 0.1 s−1). The yield stress (σy), average plateaus stress (σpl), elastic modulus (Ef) and energy absorption (Eab) increases with increase in relative density (ρrd), and also increased with increasing strain rate. Densification strain decreased with increasing strain rate and follows linear relationship with ρrd. The yield stress, elastic modulus, and densification strain were compared with Gibson-Ashby's model and are found to be in closed agreement. The stain rate parameter (Σ) marginally decreases with increase in ρrd and follows linear relationship with ρrd.