Stress Corrosion Cracking of Rare- Earth Containing Magnesium Alloy EV31A Compared With AZ91E Using Slow Strain Rate Test

摘要

Stress corrosion cracking (SCC) of the high performance rare-earth (RE) containing magnesium alloy Elektron 21 (ASTM - EV31A) was studied using slow strain rate test (SSRT). Glycerol, distilled water, and 0.01 N and 0.1 N NaCl solutions saturated with Mg(OH)_2 were employed. For comparison a well-known AZ91E alloy was also studied. SSRT studies indicate that both the alloys were susceptible to SCC to some extent in 0.1 N, 0.01 N NaCl solutions and distilled water. However, EV31A showed higher SCC resistance than A291E. The fractography of SSRT tested AZ91E and EV31A specimens were largely found to be transgranular (TGSCC) in distilled water. However in 0.1 N and 0.01 N NaCl solutions AZ91E exhibited transgranular, while EV31A showed mixed TGSCC and intergranular (IGSCC) fracture involving hydrogen embrittlement. EV31A showed lower susceptibility to SCC in all the three solutions than AZ91E, that is there is not much loss in mechanical properties of EV31A as compared to that of AZ91E in these environments.