Al–Mg–Si系合金板材の粒界腐食およびSCC特性
Al–Mg–Si系合金板材の粒界腐食およびSCC特性
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Al-Mg-Si合金板的晶间腐蚀和SCC性能
DOI：
10.2464/jilm.53.157
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
大介 長沼
中科院分区：
文献类型：
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作者：
修平 大崎;勝治 木下;大介 長沼
研究了三种Mg含量固定的Al-Mg-Si合金的晶间腐蚀（IC）和应力腐蚀开裂（SCC）性能。用2号合金（Al-0.7%Mg-0.45%Si）、5号合金（Al-0.7%Mg-1.1%Si）和7号合金（Al-0.7%Mg-0.45%Si - 0.34% cu）的冷轧薄板制备IC试样和拉伸试样，进行固溶处理，然后在448 K下时效。当采用ISO11846-B方法浸泡在酸性NaCl水溶液中，合金2号和5号对IC具有免疫力，而合金7号在过时效到过时效的大范围内对IC具有较高的敏感性。采用SSRT（慢应变速率技术）在IC试验溶液中进行拉伸试验，以评估脆性指数I（伸长率收缩率），并与实验室空气中进行比较。峰时效试样的I指数依次为5号合金、0号合金、2号合金、1号合金、7号合金，与IC敏感性的趋势不一致。在SSRT试验中，5号和2号合金的晶间应力腐蚀是由应变诱发的APC（活性路径腐蚀）引起的，并伴有沿晶界区表面膜的优先击穿，而7号合金则是由沿晶界区溶质耗尽区引起的预先存在的APC引起的。
Properties on intergranular corrosion (IC) and stress corrosion cracking (SCC) of three Al–Mg–Si alloys with a fixed Mg content were studied. IC test samples and tensile specimens were prepared from cold rolled sheets of alloy No. 2 (Al–0.7%Mg–0.45%Si), alloy No. 5 (Al–0.7%Mg–1.1%Si) and alloy No. 7 (Al–0.7%Mg–0.45%Si–0.34%Cu), subjected to solution treatment and then aging at 448 K. When immersed in an acid NaCl aqueous solution based on ISO11846–B method, alloys No. 2 and No. 5 were immune to IC, while alloy No. 7 showed a high sensitivity to IC under a wide range from underaging to overaging. Tensile tests by SSRT (slow strain rate technique) in the solution of IC tests were carried out to evaluate the index I of susceptibility to embrittlement as the ratio of reduction in elongation, compared to that in laboratory air. The index I of peak-aged specimens was ranked on the order of alloy No. 5 > No. 2 > No. 7, which disagreed with the tendency of IC susceptibility. Intergranular stresscorrosion cracks occurred in the SSRT tests were attributed to strain-induced APC (active path corrosion) for alloys No. 5 and No. 2, accompanied with preferential breakdown of surface film along grain boundary zones, while for alloy No. 7 to pre-existing APC caused by solute-depleted zone along grain boundaries.