Increasing the fatigue life and surface improvement of AL7075 alloy T6 by using ultrasonic ball burnishing process

Increasing the fatigue life and surface improvement of parts along with reducing production costs is very desirable for the industry. Ultrasonic assisted (UA) burnishing has been acknowledged as a new approach to improve fatigue life. In this research, surface hardness, hardened surface depth, and fatigue life were investigated on tempered 7075 aluminium alloy during UA burnishing. The experiments were carried out employing response surface methodology (RSM). In this regard, spindle speed, feed rate, Penetration depth, and ultrasonic power were considered as input variables of the process while vibration frequency was fixed at 20 kHz. Also, surface hardness and hardened surface depth were taken as responses to the process according to RSM. The UA burnishing showed a significant increase in the HV and hardened surface depth, as compared to the conventional burnishing process. In this respect, maximum HV and hardened surface depth were found to be 16% and 56% higher than those of the conventional burnishing process, respectively. Furthermore, fatigue life increased almost 32% when UA burnishing is employed rather than conventional burnishing.