Abstract: In this study, stainless steel powder and thin-walled steel tubes served as feedstock for fabricating a novel array-structured porous steel through vacuum sintering, exhibiting porosities of 60–65%. Reliable metallurgical bonding between stainless steel powder and the outer wall of the thin-walled steel tubes was achieved through the formation of sintering necks. However, precipitation of Cr-rich secondary phases occurred in the as-sintered samples, leading to chromium depletion within the austenitic matrix. To mitigate these microstructural characteristics, systematic solution treatments were implemented with variable holding durations. Optimal homogenization was achieved through solution treatment at 1050 °C for 30 minutes, which effectively dissolved approximately 100% of the Cr-rich secondary phases into the matrix. Mechanistic investigations under quasi-static loading conditions indicated consistent deformation behavior before and after solution treatment. Under in-plane compression, crack initiation occurred at low strain levels, followed by progressive propagation leading to complete sample failure. Conversely, out-of-plane compression demonstrated delayed crack formation localized within the outer powder region, producing more uniform deformation patterns with damage localization confined to the peripheral areas. The solution-treated samples exhibited significant enhancement in mechanical performance, particularly those processed at 1050 °C for 30 minutes showing superior compressive properties. Comparative analysis against as-sintered controls revealed improvements of 51.04% in in-plane compressive plateau stress (σ_pl), 31.92% increase in total energy absorption (E_ab), and 25% enhancement in specific energy absorption (SEA). Corresponding improvements under out-of-plane compression conditions reached 40.65%, 55.24%, and 30.85% respectively for these three critical mechanical parameters.