Elevated Temperature Baseplate Effect on Microstructure, Mechanical Properties, and Thermal Stress Evaluation by Numerical Simulation for Austenite Stainless Steel 316L Fabricated by Directed Energy Deposition

Abstract

In the present study, the effect of material deposition at the elevated temperature baseplate on the microstructure and mechanical properties was investigated and correlated to the unique thermal history by using numerical simulation. Numerical results agreed well with the experimental results of microstructure and mechanical properties. Numerical results revealed a significant decrease in temperature gradient and a 40% decrease in thermal stress due to material deposition on the elevated temperature baseplate. The reduced thermal stress and temperature gradient resulted in coarser grain features, which in turn led to a decrease in hardness and tensile strength, especially for the bottom region near the baseplate. Meanwhile, no significant effect could be found for ductility. In addition, an elevated temperature baseplate promoted less heterogeneity in hardness and tensile properties along the building direction. The current work demonstrates a collective and direct understanding of the baseplate preheating effect on thermal stress, microstructure and mechanical properties and their correlations, which is believed beneficial for the better utilization of baseplate preheating positive effects.

In-situ directed energy deposition of Al based low density steel for automotive applications

“…The density was measured by the gravimetric method, according to Archimedes principle. The hardness profiles HV5 (load 5 kg) were measured using laboratory hardness tester Struers DuraScan 50 (EMCO-TEST Prüfmaschinen GmbH, Kuchl, Austria) equipped with ecos WorkflowTM software (EMCO-TEST Prüfmaschinen GmbH, Kuchl, Austria) 22 . The hardness was measured according to ISO 6507–1: Vickers hardness measurement.…”

The thermal history of the directed energy deposition process monitored by pyrometer and camera

“…DED systems are known for their high heat input, but variations in cross-section geometry [4] and time intervals [5] during printing produce different thermal histories. An inhomogeneous thermal history leads to challenges, such as complex phase transitions, microstructural changes [6], inhomogeneous residual stresses [7], deformation [8], cracking, mechanical degradation, and premature part failure.…”