Characterization of the Role of Post-build Heat Treatment on the Localized Corrosion Susceptibility of Laser Powder Bed Fused Inconel 718 Parts

As more industries look toward additively manufactured (AM) components to combat lead times, re-design, cost of complexity, etc., those industries are faced with re-evaluating the performance of AM-based materials as compared to their well-documented wrought or machined counterparts. A particular alloy of interest to many industries including aerospace and energy/power generation is Inconel 718 (I718). Additively manufactured I718 parts typically receive a series of post-build heat treatments prior to deployment. These include stress relief, hot-isostatic pressing operations and solution aging. If not properly controlled, these post-build treatments may introduce secondary precipitates that will affect the parts susceptibility to corrosion. This is specifically true of susceptibility to localized corrosion mechanisms that may lead to crack initiation, accelerated crack growth and ultimately premature failure. By utilizing electrochemical parameter testing to analyze for pitting potentials, this work investigates the variation in tolerance to localized corrosion breakdown that results from common post-build heat treatment steps and the secondary phase precipitation that can ensue in I718 AM parts.