Rotary bending fatigue properties of Inconel 718 alloys by ultrasonic nanocrystal surface modification technique

Abstract

This study investigates the influence of ultrasonic nanocrystal surface modification (UNSM) technique on fatigue properties of SAE AMS 5662 (solution treatment) of Inconel 718 alloys. The fatigue properties of the specimens were investigated using a rotary bending fatigue tester. Results revealed that the UNSM-treated specimens showed longer fatigue life in comparison with those of the untreated specimens. The improvement in fatigue life of the UNSM-treated specimens is attributed mainly to the induced compressive residual stress, increased hardness, reduced roughness and refined grains at the top surface. Fractured surfaces were analysed using a scanning electron microscopy (SEM) in order to give insight into the effectiveness of UNSM technique on fracture mechanisms and fatigue life.

Keywords

• chromium alloys
• iron alloys
• nickel alloys
• fatigue
• internal stresses
• compressive strength
• scanning electron microscopy
• bending
• nanostructured materials
• rotary bending fatigue properties
• Inconel 718 alloys
• ultrasonic nanocrystal surface modification technique
• UNSM technique
• SAE AMS 5662
• rotary bending fatigue tester
• UNSM-treated specimens
• fatigue life
• compressive residual stress
• hardness
• fractured surfaces
• scanning electron microscopy
• SEM
• fracture mechanisms