Effects of hexagonal boron nitride content on forming quality and performance of laser powder bed fusion manufactured nickel-based hastelloy X composites

Abstract

Regulating the composition of nickel-based composites, especially those containing crack-sensitive Hastelloy X (HX) matrix, significantly influences the forming quality and performance of parts manufactured using laser powder bed fusion (LPBF). Ray tracing and temperature field simulations were conducted to analyze the non-equilibrium solidification mechanism of the laser processed hexagonal boron nitride (h-BN)-HX system, resulting in an optimized h-BN content range. The optimized composition, with 0.2 wt% h-BN in HX, showcased the best forming quality and performance. It displayed negligible cracks or unmelted particles, minimal surface roughness of 9.29 μm, and superior tensile properties with a tensile strength of 1246.49 MPa and an elongation of 18.67 %. Furthermore, the samples showcased increased hardness (371.21 HV5) and reduced friction coefficient (0.54). Interestingly, with a further increase in h-BN content, a gradual improvement in strength and hardness was observed, accompanied by a reduction in the friction coefficient. Nevertheless, the ductility of the samples noticeably decreased. The 1 wt% h-BN/HX sample exhibited a tensile strength of 1503.14 MPa, hardness of 502.13 HV5, and friction coefficient of 0.48 while displaying an elongation of only 3.76 %. These findings emphasize the significance of optimizing the composition of Ni-based composites to enhance the forming quality and performance of parts manufactured through LPBF, particularly in aerospace and engineering applications.