LC4高强铝合金的慢应变速率拉伸试验

采用慢应变速率拉伸 (SSRT)技术测试了LC4铝合金在空气和质量分数为 3.5 %的NaCl溶液中的应力腐蚀断裂 (SCC)行为 .研究了应变速率对铝合金SCC行为的影响和氢在LC4高强铝合金应力腐蚀断裂过程中的作用 .试验结果表明 ,LC4合金具有SCC敏感性 ,在潮湿空气中发生应力腐蚀断裂 ,而在干燥空气中不发生应力腐蚀断裂 .对于长横取向的LC4铝合金试样 ,在应变速率为 1.331× 10 6s 1时 ,其SCC敏感性比应变速率为 6 .6 5 5× 10 6s 1时的敏感性大 .在潮湿空气和阳极极化条件下 ,铝合金的应力腐蚀断裂机理是以阳极溶解为主 ,氢几乎不起作用 .在预渗氢或阴极极化条件下 ,氢脆起主要作用 ,预渗氢时间延长可加速LC4合金的应力腐蚀断裂 .

Slow strain rate tension test of high-strength aluminum alloy 7075

The stress corrosion cracking (SCC) behavior of aluminum alloy 7075 in air and in 3.5wt% NaClwater solution has been tested using slow strain rate tension (SSRT) technique, and the effect of strain rateand hydrogen on the SCC behavior of the alloy has been studied. The experimental results show that the alloyis susceptible to SCC which can occur in humid air but can′t in dry air. Alloy 7075 with L-T direction is moresusceptible to SCC at a strain rate of 1. 331 × 10-6 s-1 than at that of 6. 655 × 10-6 s-1. In humid air, or by anod-ic polarization in 3.5wt% NaCl water solution, the mechanism of SCC is mainly anodic dissolution. Under thecondition of hydrogen pre-permeation or cathodic polarization, hydrogen embrittlement plays a key role duringthe SCC process. The results also indicate that the SCC resistance of ahoy 7075 decreases with increasing thetime of hydrogen pre-permeation.