Metallurgical and Wear Behaviour of Stellite 6 Reinforced Stainless Steel 316 Joints by Nd-YAG Laser Welding Process

摘要

Laser welding process is a most effective and predominant method for joining of steel alloys when compared with other welding processes in practice due to their precise control of laser source across the bonding zone where it is crucial to control in other joining processes. In common the austenitic steels differ from ferritic based on two factors, thermal conductivity and expansion. Here, the selected Nd-YAG laser setup for joining of similar base material stainless steel 316 which is reinforced with and without stellite 6 powders. The experimental investigations (metallurgical survey and wear characteristics) were performed on all the samples. The powders were reinforced in the material directly by performing a drill across the bond line instead of a normal coating process which is in practice, later the powders were stuffed through the holes. Totally four samples were processed by varying the process parameters such as laser power (W), laser frequency (Hz) and keeping the time (s), feeding rate (mm/s) as constant. During the joining process the powders will get solidified with the molten steel alloy. Metallurgical study has been carried away across the weld zones for clear understanding of material behaviour and the survival of stellite powder particles. The wear characteristics were performed on the samples by keeping time, load and speed as constant, but the sliding distance is varied as (40, 50, 60) mm. The results revealed that a good agreement of stellite particles across the bonding region. It is also predicted from the experiments that joints made with addition of stellite powders instead of coating were shown a significant improvement in the grain boundary refinement and also a good wear resistance was observed which makes the alloy much more reliable than the existing one.