Effect of Laser Energy Density on the Microstructure and Texture Evolution of Hastelloy-X Alloy Fabricated by Laser Powder Bed Fusion.

Shuzhe Zhang,Wenjie Liu,Pei Wei,Bingheng Lu,Yunpei Lei,Sen Yao,Zhen Chen

doi:10.3390/ma14154305

Abstract

It is of great importance to study the microstructure and textural evolution of laser powder bed fusion (LPBF) formed Hastelloy-X alloys, in order to establish a close relationship between the process, microstructure, and properties through the regulation of the Hastelloy-X formation process parameters. In this paper, components of a Hastelloy-X alloy were formed with different laser energy densities (also known as the volume energy density VED). The densification mechanism of Hastelloy-X was studied, and the causes of defects, such as pores and cracks, were analyzed. The influence of different energy densities on grain size, texture, and orientation was investigated using an electron backscatter diffraction technique. The results show that the average grain size, primary dendrite arm spacing, and number of low angle grain boundaries increased with the increase of energy density. At the same time, the VED can strengthen the texture. The textural intensity increases with the increase of energy density. The best mechanical properties were obtained at the VED of 96 J·mm−3.

Highlights

Nickel-based superalloys are known as hard-to-cut or advanced materials due to their high working temperatures, high hardness, durability, creep opposition, and low thermal conductivity [1,2,3,4,5,6]
Tomus et al [13] found that the porosity, dendrites, molten pool boundaries, columnar grains, carbides, and dislocations were the main factors to influence the mechanical properties of Hastelloy-X specimens produced by SLM with, and without, post heat treatments
Zhang et al [16] systematically studied the effects of different process parameters on the thermal field and density of SLM GH3536 parts through experimental research and numerical simulation and found that both the width and depth of the molten pool increased with an increase in laser line energy density

Summary

Introduction

Nickel-based superalloys are known as hard-to-cut or advanced materials due to their high working temperatures, high hardness, durability, creep opposition, and low thermal conductivity [1,2,3,4,5,6]. Zhang et al [16] systematically studied the effects of different process parameters on the thermal field and density of SLM GH3536 parts through experimental research and numerical simulation and found that both the width and depth of the molten pool increased with an increase in laser line energy density. Keshavarzkermani et al [17] investigated the effect of scanning strategy and structural orientation on the solidification pattern of LPBF parts using Hastelloy-X type printing. The mechanical properties and corrosion behavior of Hastelloy-X fabricated by SLM were investigated and compared with their wrought counterpart, while the anisotropy of Hastelloy-X parts was clarified by Kong et al [18]. Many scholars have carried out in-depth investigations on Hastelloy-X from the perspectives of process optimization, mechanical properties, corrosion behavior, microstructure control, and heat treatment. The microstructure, crystal orientation, and crystal evolution in deformed grains were studied, thereby providing some reference for the application of Hastelloy-X alloy formed by LPBF

Powder and Forming Process

Effect of Energy Density on Microstructure

Effect

Effect of VED on Mechanical Properties seen from from Figure

4.4.Conclusions