Tensile and Fracture Properties Evaluation of Additively Manufactured Different Stainless Steels via Small Punch Testing

Laser powder bed fusion (LPBF) can fabricate hydraulic components with significant weight reduction, and in this study, small punch tests (SPTs) evaluated the tensile and fracture properties of four stainless steels (30Cr13, 316L, 15-5PH, 17-4PH), alongside metallographic, scanning electron microscope (SEM), and Electron Backscatter Diffraction (EBSD) analyses which examined their fracture modes, grain orientation, phase distribution, and grain boundary distribution. The tensile property results showed ductility rankings as 316L > 17-4PH > 15-5PH > 30Cr13, with correlations between Rp0.2 and Rm from SPT and uniaxial tensile tests for all four, while high-magnification SEM fractographs revealed ductile dimples on 15-5PH, 17-4PH, and 316L SPT specimens versus distinct cleavage fracture in 30Cr13. EBSD analysis indicated austenite content order as 316L > 17-4PH > 30Cr13 > 15-5PH, grain size order as 316L > 17-4PH > 15-5PH > 30Cr13, and high-angle grain boundaries ranking as 15-5PH > 30Cr13 > 17-4PH > 316L; additionally, notched SPT specimens inspected per EN 10371 for fracture toughness showed J-integral (JIC) values in the order 316L > 17-4PH > 15-5PH > 30Cr13, consistent with ductility and grain size results.