7075铝合金的力学与电化学交互作用

Interaction Between Mechanics and Electrochemistry of 7075 Aluminum Alloy

用慢应变速率拉伸(SSRT)技术研究了7075铝合金在应力腐蚀过程中的力学与电化学交互作用。结果表明,外加极化会提高7075铝合金的应力腐蚀敏感性,这种通过极化而改变铝合金表面电化学反应从而影响断裂应力的现象是一种电化学-力学效应。然而,对于不同热处理状态的7075铝合金,外加极化对敏感性的影响程度不同。增加拉伸应力,7075-RRA铝合金的阳极极化曲线略向正移,滞后环面积扩大,但并不显著。这种拉伸应力对极化曲线的影响是一种力学-电化学效应,有利于应力腐蚀裂纹的扩展。铝合金在应力腐蚀过程中的电化学作用和力学作用是交互的,彼此促进的。

The interaction between mechanics and electrochemistry during the stress corrosion cracking (SCO of 7075 aluminum alloy was studied using slow strain rate tension (SSRT) technique. The experimental results show that the SCC susceptibility of 7075 aluminum alloy would increase in anodic or cathode polarization, even under the weak polarization. This phenomenon is called as the electrochemistry-mechanics effect. However, the extent of increase was different among the alloys with various heat treatment states. For example, electrode polarization had weaker effect on SCC of 7075-RRA and 7075-T7351 alloys than on SCC of 7075-T6 alloy. With the increase of stress, the polarization curve of 7075-RRA alloy slightly moved to positive direction and the areas of reverse circle increased. This phenomenon is called as the mechanics-electrochemistry effect, which strengthened in defects and facilitated the SCC susceptibility. During the SCC of aluminum alloy, the both effects, electrochemistry-mechanics effect and mechanics-electrochemistry effect, were interactived and accelerated to each other.