8090铝锂合金薄板的应力腐蚀行为

THE STRESS CORROSTON CRACKING BEHAVIOR OF ALUMINIUM-LITHIUM 8090 ALLOY SHEET

采用慢应变速率试验法(SSRT)就应变速率、极化电位及时效条件的影响等研究了8090铝锂合金薄板在3.5％氯化钠溶中的应力腐蚀行为。其应力腐蚀敏感性随应变速率和极化电位而变化,且存在一个最敏感的应变速率(1×10^(-6)s^(-1))和一个发生应力腐蚀的临界电位(—800 mV,SCE)。8090合金薄板在欠时数状态下对应力腐蚀最敏感,峰时效状态下次之。而过时数状态下则不敏感。根据实验结果和断口形貌特征,认为8090合金薄板的应力腐蚀为阳极活性通道机制,但在强烈渗氢情况下,氢可能成为应力腐蚀的主导因素。

The stress corrosion cracking (SCC) behavior of the AI-Li 8090 alloy sheet has been evaluated by using the slow strain rate technique(SSRT). The 8090 sheet was exposed to 3.5％NaCI solution under potentiostatic conditions and tested at different tensile strain rate. The most susceptible strain rate (1×10^(-6)·s^(-1)) and a critical potential (—800mV, SCE)have been observed. Aging conditions have great influence on the susceptibility to SCC, with underaged temper being the most susceptible, peak-aged temper being less susceptible and overaged temper being non-susceptible. By synthesizing the results and the fractographie characteristics, a conclusion can be drawn that anodic dissolution is generally the main mechanism of SCC. However hydrogen embrittlement may play a dominant role in the cracking mechanism, when hydrogen heavily permeats into the materials.