ABSTRACT Recent work has indicated that a galvanic as well as chemical protection mechanism may control the intergranular stress corrosioncracking (IG-SCC) mitigation achieved by Zn-rich primers on Al-Mg alloys [1]. The effect of Zn salt species content added to the bulk NaCl environment on IG-SCC severity at -0.9 VSCE was evaluated using a highly susceptible condition of AA5456-H116. Linear elastic fracture mechanics-based testing demonstrated that, for a constant [Cl–], the threshold stress intensity for IG-SCC increased under these conditions and the IG-SCC growth rate was significantly suppressed with increasing stress intensity in the presence of Zn ions. Titration of ZnCl2 into Al-Mg simulated crack tip solution indicates that Zn salt species may reduce crack tip acidification and thereby raise the pH of the crack tip. These results support the combined galvanic and chemical protection that may be achieved through use of Zn-rich primers for IG-SCC mitigation on AA5456-H116.

中文翻译：

---

Zn2+ 对高敏化铝镁合金应力腐蚀开裂严重程度的影响

摘要 最近的工作表明，电流和化学保护机制可以控制通过富锌底漆在铝镁合金上实现的晶间应力腐蚀开裂 (IG-SCC) 缓解 [1]。使用高度敏感的 AA5456-H116 条件评估了添加到大量 NaCl 环境中的锌盐物质含量对 -0.9 VSCE 下 IG-SCC 严重性的影响。基于线弹性断裂力学的测试表明，对于恒定的 [Cl–]，在这些条件下 IG-SCC 的阈值应力强度增加，并且在 Zn 离子存在下，IG-SCC 的生长速率随着应力强度的增加而受到显着抑制. 将 ZnCl2 滴定到 Al-Mg 模拟裂纹尖端溶液中表明 Zn 盐物种可以减少裂纹尖端酸化，从而提高裂纹尖端的 ​​pH 值。