Microstructure and Mechanical Anisotropy of Ni–Mo–Cr-Based Alloy Manufactured by Laser Metal Deposition

Abstract

This study investigated the microstructure and mechanical anisotropy of laser metal deposited NiMoCr super alloy. The laser metal deposited NiMoCr super alloy showed a unidirectional micro-columnar structure. The £ phase was observed in the form of fine dendrites, and M 6 C (fishbone type) was shown in inter-dendrite regions. A room temperature compression test was conducted on specimens prepared in different directions (ND, PD), with strain rates of 10 ¹3 ³1 s ¹1 . As the strain rate increased, there was a tendency for strength to increase in both directions. As compression stress was applied, M 6 C fractured and aligned in the vertical direction of compression, and linear fracturing occurred in the PD (printing) direction, and zig-zag fracturing occurred in the ND (normal) direction. As the strain rate increased, the fractured M 6 C size became finer, and cracks were formed and developed along the carbides that caused the fracturing. In particular, while detachment occurred due to carbides in the ND direction, a more compressed form was observed in the PD direction. Therefore, it is considered that the PD direction has relatively higher yield strength and greater strain rate sensitivity than the ND direction. [