Influence of Laser Energy Input on the Microstructure and Properties of 8620 Low-Alloy Steel Fabricated by Laser Powder Bed Fusion

This research, conducted with meticulous attention to detail, is of significant importance as it investigates the effects of different laser energy inputs on the microstructure and mechanical properties of 8620 low-alloy steel samples prepared by laser powder bed fusion (LPBF). The optimal laser energy input, crucial for enhancing the comprehensive properties of the samples, was obtained by comparing the relative density. The density of 8620 samples was directly affected by the change in laser energy input (67.90 - 138.89 J/mm(3)). The sample exhibited a relative density of 96.41% when the high laser energy input was 138.89 J/mm(3). In contrast, at a lower laser energy input of 67.90 J/mm(3), the relative density of the sample was 96.01%. However, the sample's maximum density at the optimal laser energy input (88.89 J/mm(3)) could reach 99.67%. Microstructure observation showed that the martensite, ferrite, and bainite were obtained in LPBF-fabricated 8620 samples. By optimizing the process parameters, we were able to get 8620 low-alloy high-strength steel with a high hardness value of similar to 454.5 HV (at 101.01 J/mm(3)) and ultimate tensile strength of similar to 1.18 GPa (at 88.89 J/mm(3)). These findings, derived from a thorough and meticulous research process, establish a robust foundation for the LPBF of high-performance, low-alloy steel samples, offering significant potential for enhancing their mechanical properties.