Pulsed fiber laser processing of A4 SS under active and inactive environments: A comparative study

Abstract

Higher machining productivity and improved surface functionalities are major concerns in laser micromachining. A pulsed fiber laser process (PFLP) is asserted in this study for producing micro-channels on A4 stainless steel (A4 SS) for marine applications. As PFLP is one of the most demanding manufacturing processes, this research aims to enhance PFLP by introducing a novel linear orbit-in-orbit laser beam position approach (LO-OLPA). This innovative method was further investigated in active and inactive gas environments as an existing industrial potential by altering the PFLP variables via tailoring the scan modes of the fiber laser. Furthermore, responses such as material ablation, dimensional, and surface characteristics were compared. The response functions were then used for multi-response whale optimization (MRWO) to acquire the best parametric settings for both environments to enhance productivity and quality. Later, surface analysis (such as surface morphology, elemental diffusions, phase quantifications, and molecular bond identification) was studied in two environments. The results demonstrated that the exothermic chemical reaction boosted the material ablation and dimensional aspects of A4 SS during PFLP but impaired the surface quality when the environment switched from inactive to active. Also, in both conditions, the entry side of the channels is rich in Fe and Cr oxides, but the exit side has just Cr oxide. Elements including Cr, and Fe were revealed to be more abundant in the evacuated molten materiallayer under inactive compared to the active environment. In addition, molecular bond displacement was detected in both environments compared to the base material.