Effect of flap peening on stress corrosion cracking resistance of 7B04-T6 alloy

Abstract

The flap peening method with two different shot peening intensities were used to strength the 7B04-T6 for studying the effect of shot peeing on the stress corrosion cracking resistance and mechanical properties of 7B04-T6. Comparative testing about surface roughness, surface residual stress, surface topography, constant load stress corrosion cracking experiment and static strength tensile experiment were performed, the fracture surfaces were observed with SEM. The results show that, shot peening has imparted a surface residual compressive stress of −350 MPa (0.1-0.2 A intensity) and −275 MPa (0.2-0.3 A intensity). The surface roughness has increased from Ra 0.9 μm to Ra 1.6 μm (0.1-0.2 A intensity) and Ra 1.8 μm (0.2-0.3 A intensity). The duration of stress corrosion cracking has extended with 11.3 times (0.1-0.2 A intensity) and 8.7 times (0.2-0.3 A intensity) in the 3%NaCl + 0.5%H2O2 solution and with an application of 350 MPa load. Shot peening has not influenced the ultimate strength and percentage reduction in area, but slightly decreased the yield strength with a value of 15 MPa.

Keywords

• flap peening
• 7b04-t6
• scc
• residual stress
• static strength