Mechanical Property Characterization of Single Scan Laser Tracks of Nickel Superalloy 625 by Nanoindentation

Published: March 14, 2019

Author(s)

Jordan S. Weaver, Meir Kreitman, Jarred C. Heigel, M A. Donmez

Abstract

Laser based additive manufacturing of metals relies on many micro-sized welds to build a part. A simplified, well studied case of this process is a single scan of the laser across a single layer of powder. However, there is a lack of mechanical property measurements of the tracks produced in such experiments. Nanoindentation measurements on laser track cross-sections of nickel super alloy 625 reveal hardness differences between the track melt pool and base material as well as variations with laser scan speed. There is a change from ≈5.5 GPa in the track melt pool to ≈4.8 GPa in the base material for laser settings of 195 W and 800 mm s−1. In comparison, the increase in hardness in the melt pool is not observed for settings of 195 W and 200 mm s−1. It is believed that the difference in thermal histories supported by thermographic measurements causes a difference in the dislocation density in the melt pool. This results in a difference in hardness between the two tracks. The effects of the local crystal orientation, dendritic spacing, and residual stress are considered in the interpretation of results.
Proceedings Title: TMS 2019 Conference Proceedings
Conference Dates: March 10-14, 2019
Conference Location: San Antonio, TX
Conference Title: TMS 2019
Pub Type: Conferences

Keywords

additive manufacturing, hardness, residual stress, microstructure, electron backscatter diffraction
Created March 14, 2019, Updated March 11, 2019