Effect of post-weld heat treatment on heat affected zone microstructure of additively manufactured Inconel 718

Abstract

Laser powder bed fusion for metals is a method of producing end use components for industrial use. Powder bed fusion machines are relatively small, and are usually used to create only the critical part of the larger assembly. Therefore, L-PBF manufactured parts must be attached to each other for example by welding. The industrial world needs to be able to join the printed superalloy components to the traditionally manufactured components to reach better corrosion, wear and/or heat resistance in selected parts in an assembly. The problem is that there is limited amount of information about the suitable welding parameter values for these applications. This study examines how the standard heat treatment cycles affect to the quality of the weld, and if the post-heat treatment is reducing undesired phases in the heat affected zone. Test has shown that post heat treatment highlights cuboidal shaped niobium rich carbides throughout the material to the heat affected zone grain boundaries.