Microstructure and corrosion of SLM IN718 in 3.5% NaCl solution at high temperatures

Abstract

This study investigated the temperature dependence of IN718 corrosion behavior in 3.5 wt. % NaCl solution, comparing conventionally rolled (Roll) and SLM-manufactured (SLM) samples. While both exhibited degradation with increasing temperature, the Roll sample presented a significantly higher susceptibility to corrosion by increasing the temperature from 25 to 70 °C. Rapid corrosion current density (icorr) of the Roll sample, which increased from 0.25 to 1.3 μA cm2, suggested the preferential γ-matrix dissolution and microgalvanic attack triggered by Laves phases and carbides acting as preferential dissolution sites. Conversely, the SLM sample showcased less segregation and fewer carbide phases due to its high cooling rate, resulting in a milder icorr rise (0.45–0.6 μA cm2). The findings hold promise for a more comprehensive understanding of IN718 performance and can guide the selection of optimal fabrication methods for components exposed to corrosive and high-temperature environments.