Abstract
Rotary friction welding (RFW) is one of the most important processes for bonding metal together, either alike or unlike. RFW has gained acceptance among many manufacturing sectors because it reduces thermal distortion, produces fewer heat affected zone areas, provides for increased production rates, and eliminates the need for filler metals. The focus of this investigation was the mechanical properties of welds with an emphasis placed upon the relationship of spindle speed with the quality of the welds for three different types of materials that are bonded; i.e., aluminium-aluminium, steel-aluminium, and steel-steel. These welds were fabricated utilising the rotary friction welding technique at a lathe. Tensile tests were performed to measure how well the welds would perform under stress. Ultrasonic inspections were completed to find any cracks or holes inside the welds. Micro measurements were taken to assess the weld zone. Hardness tests were performed to determine the amount of resistance the material could withstand. Finally, metallographic analysis was conducted to examine the micro structural characteristics of the welds. The tests revealed that as the spindle speed increased so did the loss of elastic resistance of the welds. It was determined that this loss of elastic resistance resulted from the high temperatures produced by the high spindle speeds causing micro-structure softening. At 1,250 RPM, the optimal (mechanical) performance was found as well as the highest level of mechanical properties such as strength and hardness. Furthermore, through ultrasonic testing, it was confirmed that all weld seams produced by RFW were completely free of defects. Therefore, these results clearly demonstrate that RFW can produce weld seams with high mechanical properties and no defects if optimum process conditions exist, especially if the spindle speed is adjusted to match the respective materials