Laser Welding of 316L Austenitic Stainless Steel in an Air and a Water Environment

Laser welding is an innovative method that is frequently used and required by different disciplines and represents a technique of choice in a wide range of applications due to important advantages such as precision, speed, and flexibility. However, the welding method must be used properly otherwise it may deteriorate the mechanical properties of the welded metal and its environment. Therefore, the laser parameters should be precisely determined and carefully applied to the sample. The primary objective of this study was to investigate and propose optimal welding parameters that should be adjusted during the neodymium-doped yttrium aluminum garnet (Nd: YAG)-pulsed laser welding of austenitic stainless steel 316L in an air welding environment by using Argon shielding gas and in wet welding settings in serum medium. The investigation of the welding process in serum medium was conducted in order to propose the most suitable welding parameters being important for future possible medical applications of laser welding in in-vivo settings and thus to investigate the possibilities of the welding process inside the human body. In order to evaluate the quality of welding in air and of wet welding (in serum), a detailed parameter study has been conducted by variation of the laser energy, the welding speed and the focal position. The relationship between the depth of penetration and specific point energy (SPE) was also evaluated. The microstructure of the welded metal was examined by an optical microscope and scanning electron microscope (SEM). Based on the microscopy results, it was found that the largest depth of penetration (1380 µm) was achieved with 19 J laser energy in air medium, while the depth reached the largest value (1240 µm) in serum medium at 28 J laser energy. The increasing energy level showed opposite behavior for air and serum. The results of our study imply that when welding of 316L stainless steel is implemented properly in the body fluid, it would be a promising start for future in-vivo studies.