Research on the seawater corrosion resistance mechanism of 7075 aluminum alloy based on combination strengthened gradient surface construction

This study investigates the seawater corrosion resistance mechanism of 7075 aluminum alloy by constructing a composite reinforced gradient surface. The research focuses on the impact of ultrasonic impact-solid shot peening and water jet (UIT-SPEWJ) combined surface modification on the seawater corrosion behavior of 7075T6 aluminum alloy in natural seawater environments. Surface morphology, microstructural characterization, and electrochemical corrosion tests were analyzed to understand these effects. The findings reveal that in the seawater corrosion environment, the surface of the 7075-T6 aluminum alloy was covered with blocky corrosion products. The UIT-SPEWJ combined surface modification led to grain refinement, increased grain numbers, and a notable reduction in electrochemical corrosion current density. A positive shift in corrosion potential and a larger capacitive arc radius were also observed. Among the modified samples, the UIT-SPEWJ method resulted in the lowest corrosion current density at 2.697E-6 A/cm2 and the most positive corrosion potential at -0.701 V. This combined surface modification approach significantly enhanced the seawater corrosion resistance of the 7075-T6 aluminum alloy.