Effects of Environments and Polarization Potential on the Stress Corrosion Cracking in High-Strength Aluminum Alloys

高強度アルミニウム合金の応力腐食割れに及ぼす環境および分極電位の影響

Effects of Environments and Polarization Potential on the Stress Corrosion Cracking in High-Strength Aluminum Alloys

Creators Ohsaki Shuhei

Creators Takahashi Tsuneo

Constant extension rate tests were conducted to determine the effects of environment and polarization potential on the stress corrosion cracking (SCC) behaviors in the short-transverse direction of wrought high-strength aluminum alloys 7075 and 7475 in thick sections. The specimens in T6 condition of the alloys reveal a noticeable embrittlement due to SCC when tested in laboratory air, and thus it gives misleading results to employ laboratory air as a reference environment for evaluating SCC susceptibility. The susceptibility can be expressed well in terms of the ratio of the elongation to fracture in a corrosive environment to that in dry nitrogen gas. The SCC behaviors in a NaCl solution, greatly depending on the polarization potential, can be classified into the four potential ranges with the modes of corrosion attack. The high-purity alloy 7475 shows a more enhanced SCC resistance than 7075.

[ISSN]0372-7661

[NCID]AN00244228