Susceptibility to Stress Corrosion Cracking of AZ31B Magnesium Alloy by Slow Strain-Rate Technique
Hitoshi UCHIDA, Masato YAMASHITA, Satoshi HANAKI and Takahiko NOZAKI
Abstract:Due to advantages such as high strength-to-weight ratios, specific castability and recycling efficiency, magnesium alloys are used in a wide variety of industrial applications. Stress corrosion cracking (SCC) tests of AZ31B magnesium alloy in distilled water and 2`8wt% sodium chloride solutions at 298K were performed with slow strain-rate technique. In a distilled water, the SCC of the magnesium alloy occurs surely and its susceptibility increases with a decrease of strain-rate. This magnesium alloy in sodium chloride solutions is very susceptible to the SCC under open circuit condition, regardless of the strain-rate and solution concentration. The SCC in 4wt% sodium chloride solution under potential-controlled condition occurs near the corrosion potential, which lies to the potential range of hydrogen evolution. Furthermore, the fracture surface is characterized by transgranular quasi-cleavage appearance. The evidence introduced here supports a hydrogen embrittlement for the SCC of AZ31B magnesium alloy in sodium chloride solution, including an anodic dissolution mechanism by chloride ion. Key Words:Magnesium alloy, Stress corrosion cracking, Slow strain-rate technique, Hydrogen embrittlement