Effect of aging processes on corrosion behavior and stress corrosion sensitivity of pre‐stretched 7075 aluminum alloy

Abstract

In this work, the microstructures, corrosion behavior, and sensitivity to stress corrosion cracking (SCC) of pre‐stretched 7075 aluminum alloy drill pipes with 2.5–3% tensile plastic deformation in a 3.5% sodium chloride solution are studied. The alloy samples are separately subjected to single‐stage aging, two‐stage aging, and three‐stage aging. The polarization curves of the samples all demonstrate passivation characteristics after the different aging treatments. Single‐stage aging of the sample results in poor corrosion resistance and high SCC sensitivity with continuously distributed grain boundaries. After two‐stage aging, the sample exhibits improved corrosion resistance and SCC sensitivity, with intermittently distributed grain boundaries. Three‐stage aging imparts the alloy with remarkable corrosion resistance and significantly reduced SCC sensitivity, with intermittently distributed grain boundaries. Thus, the three‐stage sample is considered to be the best choice for aluminum alloy drill pipes intended for applications involving heat‐treatment.