Localized Corrosion in Additively Manufactured Stainless Steel and Aluminum Alloys

Localized corrosion susceptibility represents a risk to the long-term performance of all materials, additively manufactured (AM) alloys included. Understanding the impact of AM on localized corrosion resistance is at an early stage, but the unique microstructures that result from AM can have a dramatic impact on corrosion susceptibility and morphology. These microstructures also impact the response of AM alloys to standardized testing. AM 316L is shown to respond very differently to ASTM tests for intergranular corrosion susceptibility that were developed for and used to assess wrought austenitic stainless steels. The damage morphology and the impact of heat treatments are shown to vary significantly between cast A360 aluminum alloy and AM Al-10Si-Mg upon exposure to ASTM standard G85, a workhorse of aluminum alloy corrosion testing. AM build parameters can have dramatic effects on the susceptibility, likely through their impact on the lifetime of the liquid phase during manufacture.