Al-Mg-Si系合金の応力腐食割れ特性に及ぼすCr添加の効果
Al-Mg-Si系合金の応力腐食割れ特性に及ぼすCr添加の効果
复制标题
Cr添加量对Al-Mg-Si合金应力腐蚀开裂性能的影响
DOI：
10.2464/jilm.55.350
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
勝治 木下
中科院分区：
文献类型：
--
作者：
修平 大崎;秀樹 近藤;勝治 木下
研究了添加Cr对4种Al-Mg-Si合金在酸性氯化钠（ISO）溶液中晶间腐蚀（IC）和应力腐蚀开裂（SCC）性能的影响。5号（Al-Mg-1.1%Si）、7号（Al-Mg-0.44Si-0.34Cu）以及分别添加0.2%Cr的C5号和C7号合金。过量Si合金No.5和No.C5在443 K时效的任何阶段都表现出对IC的小敏感性，而含Cu合金No.7和No.C7在欠时效到峰值时效的阶段（448 K下28.8ks）表现出一定的IC。然而，C7号合金在过时效阶段变得对IC免疫。在应变速率为5.5×10-7/s的条件下进行了慢应变速率拉伸试验，以评估SCC敏感性指数I，即伸长率降低率，并与实验室空气中的SCC敏感性指数I进行了比较。峰值时效试样的指数I的顺序为5号合金（0.98）> 7号合金（0.72）> C7号合金（0.69）> C5号合金（0.23），这与通过恒定载荷SCC试验获得的失效时间特性良好对应。因此，SSRT应该是一种有用的快速测试方法，以估计SCC阻力。在过量的Si合金中加入Cr，可显著提高合金的抗SCC性能。C5合金的高电阻归因于由于细晶粒结构和晶粒中弥散相AlSi（Cr，Fe）或AlSiFe的分布而增加的均匀腐蚀。
Effect of Cr addition on properties of intergranular corrosion (IC) and stress corrosion cracking (SCC) in an acid sodium chloride (ISO) solution was evaluated by using four kinds of Al-Mg-Si alloys with a constant Mg content of 0.7mass% ; No. 5 (Al-Mg-1.1%Si), No. 7 (Al-Mg-0.44Si-0.34Cu), and alloys No. C5 and No. C7 with 0.2% Cr addition respectively. The excess Si alloys No. 5 and No. C5 showed little susceptibility to IC at any stage of aging at 443K, whereas the Cu containing alloys No. 7 and No. C7 exhibited some IC at the stage from underaging to peak-aging (for 28.8 ks at 448K). The alloy No. C7 however became immune to IC at the stage of overaging. Tensile tests by SSRT (slow strain rate technique) were carried out at strain rate 5.5×10-7/s to evaluate the index I of susceptibility to SCC as the ratio of reduction in elongation, compared to that in laboratory air. The index I of the peak-aged specimen was ranked on the order of alloy No. 5 (0.98)>No. 7 (0.72)>No. C7 (0.69)>No. C5 (0.23), which was in a good correspondence to the failure-time property obtained by a constant load SCC test. SSRT therefore should be useful as a rapid testing method to estimate SCC resistance. The Cr addition to the excess Si alloy resulted in a marked improvement of SCC resistance. The high resistance of alloy No. C5 were attributed to an increase in uniform corrosion due to a fine grain structure and distribution of dispersoids AlSi (Cr, Fe) or AlSiFe in grains.