The effect of ultrasonic vibrations on mechanical properties of low carbon steel-pure titanium bilayer sheet in incremental sheet forming process

Incremental Sheet forming (ISF) is one of the processes for producing sheet metal parts without the use of mold that has been developed to allow rapid prototyping and reduced time and cost of fabricating parts. In this process, as well as other forming processes, reducing of the forming force and improving of the mechanical properties of the created part are considered. For which purpose, various methods have been developed. One of these methods is the use of ultrasonic vibration and its application to the process. In this study, ultrasonic vibrations were used on the tool to improve the mechanical properties of the piece made in the incremental sheet forming process. The purpose of this study was to investigate the effect of ultrasonic vibration on the mechanical properties of parts made in the incremental forming process. So, suitable equipment for this process was designed and constructed. Then, pyramidal samples were produced under different conditions of horizontal and vertical feed rates under the influence of ultrasonic vibration and hardness and tensile testing were performed on the produced specimens. The results showed that hardness and tensile strength increased by 50% and 30% respectively, due to the applying ultrasonic vibration. Microstructural studies on the samples showed that due to the temperature increase of the samples as a result of the conversion of ultrasonic vibration into the heat, the continuous dynamic recrystallization (CDRX) process occurred in the microstructure of the samples, which resulted in the grain refinement and improvement in the mechanical properties.