Free Vibration Study of Nd-YAG Laser welded Stainless Steel 316 joints Reinforced with Stellite Powder

Abstract

Abstract Laser welding is an unique joining process especially for stainless steels and the time consumed to make the joints is literally very less when compared to other joining processes. Laser welding process uses a nozzle which focusses the laser source over the joint in order to make the weld irrespective of either similar or dissimilar materials. The depth of penetration of laser source can be controlled by laser power and focal position which is difficult to achieve it in other welding processes. However, lot of studies have been carried out to investigate the metallurgical and mechanical properties of joints by laser welding process. In the present work, an attempt was made to study the vibrational characteristics of stainless steel 316 reinforced with Stellite grade 6 powderprocessed by Nd-YAG laser setup. Three samples were processedby varying the power and frequency of laser setup keeping the other two parameters - travel speed and time - unchanged. Free vibration analysis was carried out using an accelerometer, data acquisition card and plots were drawn with the assist of Dewe software. The natural frequency and damping were measured for all the samples by processing the signal from the accelerometer mounted near the weld zone of the samples. Each sample has been tested with five trials and the average value of the measuring parameters has been considered in order to minimize the measuring errors. The results revealed that the variation of laser power and its frequency have an impact on the natural frequency and damping of the samples. Though natural frequencies, damping can be modified by different techniques, the present study proved that it can even be modified with the laser source parameters. Thus the research work helps designer to efficiently design the laser welded structure excited with various dynamic loads by further optimizing the laser source parameters.