Comparison of the wear and corrosion resistance of 17-4PH manufactured by SLM and micro-SLM

The excellent corrosion resistance of 17-4PH stainless steel has led to its widespread application in aerospace and energy sectors. With the increasing demand for miniaturized and geometrically complex structures, additive manufacturing processes capable of higher resolution and precision, such as micro-selective laser melting (µSLM), are increasing attention compared to conventional selective laser melting (SLM). This study systematically compares the wear and corrosion performance of dense 17-4PH components fabricated using optimized printing parameters. XRD phase analysis revealed that the µSLM components consisted predominantly of an FCC structure, while the SLM components were mainly composed of a BCC phase. Hardness tests indicated a moderately lower value for µSLM components (296 HV_0.2) than for SLM components (356 HV_0.2). However, reciprocating vibration wear tests revealed that the µSLM components possess superior wear resistance. In particular, the wear volume of the µSLM components was found to be approximately four times lower than that of the SLM components, accompanied by a significantly reduced wear depth. In contrast, polarization curve tests in NaCl solution indicated a slightly inferior corrosion resistance for the µSLM components. Compared to the SLM components, µSLM components exhibited a lower corrosion potential and a higher corrosion current density, indicating a reduced resistance to electrochemical degradation. The observed microstructural differences between the two component types are primarily attributed to the laser intensity and particle size of the feedstock used during the printing process. The enhanced wear resistance of µSLM components is closely related to the FCC phase, which provides increased toughness despite the lower hardness. In contrast, the inferior corrosion performance of µSLM components is likely associated with an increased level of porosity inherent to the µSLM process.