Effect of Hydrogen on Corrosion and Stress Corrosion Cracking of AZ91 Alloy in Aqueous Solutions

• Published in: Acta metallurgica sinica : English letters Vol. 29; no. 1; pp. 1 - 7
• Main Authors: Chen, Jian, Wang, Jian-Qiu, Han, En-Hou, Ke, Wei, Shoesmith, D. W.
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Society for Metals 2016; Springer Nature B.V
• Subjects: Aqueous solutions; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion; Corrosion and Coatings; Corrosion effects; Corrosion rate; Crack initiation; Electrodes; Electrolytes; Grain boundaries; Hydrides; Hydrogen; Hydrogen embrittlement; Hydrogen storage; Incompatibility; Magnesium; Magnesium alloys; Magnesium base alloys; Materials Science; Mechanical properties; Metallic Materials; Nanotechnology; Organometallic Chemistry; Spectroscopy/Spectrometry; Spectrum analysis; Stress corrosion cracking; Tribology; X-rays; 分析; 金属学; 金属物理学; 金相学; Transgulanar stress corrosion cracking (TGSCC); AZ91 alloy; Corrosion; Hydrogen; Secondary ion mass spectroscopy (SIMS)
• ISSN: 1006-7191; 2194-1289
• DOI: 10.1007/s40195-015-0358-x

The effect of hydrogen on the corrosion and stress corrosion cracking of the magnesium AZ91 alloy has been investigated in aqueous solutions. Hydrogen produced by corrosion in water diffuses into, and reacts with the Mg matrix to form hydride. Some of the hydrogen accumulates at hydride/Mg matrix （or secondary phase） interfaces as a consequence of slow hydride formation and the incompatibility of the hydride with the Mg matrix （or secondary phase）, and combines to form molecular hydrogen. This leads to the development of a local pressure at the hydride/Mg matrix （or secondary phase） interface. The expansion stress caused by hydride formation and the local hydrogen pressure due to its accumulation result in brittle fracture of hydride. These two combined effects promote both the corrosion rate of the AZ91 alloy, and crack initiation and propagation even in the absence of an external load. Hydrogen absorption leads to a dramatic deterioration in the mechanical properties of the AZ91 alloy, indicating that hydrogen embrittlement is responsible for transgulanar stress corrosion cracking in aqueous solutions.