Micro-Mechanical Property Evaluation of Heat-Treated Metal 3D Printed Parts Affected by Process Interruptions

Metal additive manufacturing techniques enable rapid prototyping and on-demand manufacturing while improving supply chain resiliency.Changes in microstructure and micro-mechanical characteristics of 3D printed metal parts occur due to the influence of process interruptions on melting-solidification cycles during the layer evolution in additive manufacturing processes.The process interruption can deteriorate the structural integrity of the 3D printed parts and generate micro-flaws in the interruption region.There are a variety of techniques which can remove or reduce the amount or size of micro-flaws.Manufacturing post-processing techniques such as Heat-Treatment methods can enhance the mechanical properties of the parts.Since variations commonly happen at the layer level, the investigation of mechanical properties must be done such that these variations can be effectively identified, evaluated, and used to inform post-processing needs.Hence, this study investigates the influence of process interruption on the micro-mechanical properties of the metal 3D printed parts for stainless steel parts with and without post-processing.Accordingly, various stainless steel 316L parts are fabricated using powder-bed fusion additive manufacturing process.Manufacturing processes included different process lags.Nano-indentation testing is used to measure the elasticity and hardness.Measurements are recorded in a matrix grid form covering the interruption region of the manufacturing process.Measurement results of measurement are analyzed to detect potential variations caused by the process interruption.To investigate the influence of the post-processing procedures on the enhancements of mechanical properties of the parts, a group of parts were heat-treated in a vacuum furnace.Micro-mechanical properties were also measured for the parts with heat-treated post-processing.Results indicate that process interruptions and lags alter the mechanical properties of the parts; however, the variation can be reduced using post-processing procedures.