AZ91D镁合金在两种盐溶液和空气中的一般腐蚀和应力腐蚀

GENERAL CORROSION AND STRESS CORROSION OF AZ91D IN TWO SALT SOLUTIONS AND AIR

分别在pH值为6的0．60mol/L NaCl,0．60mol/L NaNO_3溶液和空气介质中对AZ91D压铸镁合金进行了一般腐蚀和慢应变速率试验。结果表明：该合金发生的一般腐蚀或应力腐蚀都具有明显的离子选择性,在含Cl^-的溶液中一般腐蚀较严重,在含NO_3^-的溶液中应力腐蚀更为明显。该合金在实验室空气介质中不易发生应力腐蚀。应变速率是该合金发生应力腐蚀的又一重要参数,当应变速率低于8．33×10^(-5)s^(-1)时,该合金在两种溶液中均发生应力腐蚀,在4．17×10^(-5)s^(-1)的应变速率下,应力腐蚀最为严重,应力腐蚀是阳极溶解和氢致开裂共同作用的结果。

The corrosion test and slow strain rate test of die cast AZ91D magnesium alloy in 0.60mol/L NaCl and NaNO3 solutions at pH 6 as welt as in air were carried out. The selectivity of anions for general corrosion and stress corrosion of AZ91D was obvious. The general corrosion was easier in the presence of Cl^-, while the stress corrosion was more severe with the presence of NO3. Stress corrosion did not occurr in laboratory stationary air. The strain rate was another important parameter for stress corrosion. The stress corrosion of AZ91D took place only when the strain rate was less than 8.33×10^-5s^-1 in NaNO3 or NaCl solution, and the stress corrosion was the most severe when the strain rate was equal to 4.17×10^-5s^-1. The stress corrosion was caused by anodie dissolution along with hydrogen embrittlement.