Abstract

The effect of ultrasonic shot peening on the environmental hydrogen embrittlement behavior of the 7075-T6 aluminum alloy is investigated. The 7075-T6 tensile specimens were treated by ultrasonic shot peening for 50 s. Surface residual stress and the depth of residual stress under the surface were evaluated using an X-ray diffractometer. Then, the specimens were tensile tested in humid air and dry nitrogen gas by the slow strain rate technique. The results showed that the ultrasonic shot-peened specimen has a superior hydrogen embrittlement resistance. Further, the ultrasonic shot peening changes the fracture mode from an intergranular fracture mode to the transgranular one. It was suggested that ultrasonic shot-peening has two effects on hydrogen embrittlement behavior; the distribution of hydrogen inside the surface layer by introducing dislocations/vacancies as hydrogen traps and reducing the normalized amount of hydrogen trapped per unit length of the grain boundary.

Highlights

  • Advanced materials are essential for boosting the fuel economy of modern automobiles while maintaining safety and performance

  • The residualcharacterized stresses induced in the ultrasonic shot-peened specimen as a function using a scanning electron microscope (SEM)

  • Surface The are shown in Figure 1. of Residual stresses formed during the ulT6 alloy ranged from

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Summary

Introduction

Advanced materials are essential for boosting the fuel economy of modern automobiles while maintaining safety and performance. Replacing cast iron and traditional steel components with lightweight materials such as high-strength 7xxx series aluminum (Al) alloys can directly reduce the weight of a vehicle’s body and chassis by up to 50 percent and, reduce the fuel consumption of a vehicle [1,2,3,4]. Materials used in automobile components may encounter challenges from high stress in environments with a humidity of more than 40% [5]. Such service conditions require structural materials to possess both high strength and good hydrogen embrittlement (HE) resistance. Considerable studies have been conducted to develop a high-strength HE-resistant aluminum alloy through the optimization of alloy composition and heat treatment

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