Influence of temporal laser emission profile on the selective laser melting (SLM) of thin structures

Recent experimental works on the influence of laser emission modulation on the selective laser melting (SLM) process demonstrated the interest of using a pulsed energetic input to prevent typical defects observed in SLM-built thin structures; however, the underlying physical phenomena are not yet fully understood. Two in-house platforms, one experimental and one numerical, allowing for the study of pulsed wave (PW) versus continuous wave (CW) laser emissions were developed. Both experiments and finite element (FE) simulations were performed comparing the two strategies for the building of thin structures (1 × 10 mm2) in AISI 316L stainless steel. Comparison of in situ process monitored and simulated melt pool widths and lengths showed the ability of the model to describe the thermal field behavior during the SLM process. Numerical results were used to identify and analyse the phenomena creating the empirically observed defects. Excessive heating was denoted in CW regime, which can be circumvented using PW laser emission. Simulations confirmed PW as a promising alternative to reduce defects such as part protrusion. The model proved to be a relevant tool to speed up process parameter optimization procedures and prevent defects at a design stage.