Gigacycle fatigue behavior by ultrasonic nanocrystalline surface modification

Area of Science:

• Materials Science
• Surface Engineering
• Mechanical Engineering

Background:

• Al6061-T6 alloy is a widely used material in various industries.
• Surface properties significantly influence material fatigue behavior.
• Improving fatigue resistance is crucial for extending component lifespan.

Purpose of the Study:

• To investigate the effect of Ultrasonic Nanocrystalline Surface Modification (UNSM) on Al6061-T6 alloy.
• To evaluate the microhardness and fatigue behavior of UNSM-treated Al6061-T6 alloy.
• To compare the fatigue performance of treated and untreated specimens.

Main Methods:

• UNSM was applied to create a nanocrystalline surface layer up to 84 micrometers thick.
• Vickers microhardness tests were conducted on the modified layers.
• Ultrasonic Fatigue Testing (UFT) rig was used to assess fatigue behavior up to 10^9 cycles.
• Microstructural characterization was performed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).

Main Results:

• UNSM treatment resulted in a refined grain structure in the surface layer, with grain size increasing with depth.
• Microhardness increased significantly from 116 HV to 150 HV in the treated specimens.
• Fatigue performance of UNSM-treated Al6061-T6 alloy was enhanced compared to untreated specimens.

Conclusions:

• UNSM is an effective surface treatment for enhancing the microhardness of Al6061-T6 alloy.
• The nanocrystalline surface layer created by UNSM improves the fatigue life of Al6061-T6 alloy.
• Microstructural refinement and increased surface hardness are key factors contributing to improved fatigue resistance.