Stress Corrosion Cracking of a Forged Mg-Al-Zn Alloy with Different Surface Conditions
Stress Corrosion Cracking of a Forged Mg-Al-Zn Alloy with Different Surface Conditions
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DOI：
10.1155/2018/4262860
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发表时间：
2018
影响因子：
3
通讯作者：
Z. Yin;F. Liu;D. Song;Shihuan He;J. Lin;Feng Yu
中科院分区：
文献类型：
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作者：
Z. Yin;F. Liu;D. Song;Shihuan He;J. Lin;Feng Yu
通过四点弯曲试验和氯化钠溶液交替浸泡试验，研究了不同表面状态的锻造Mg-Al-Zn镁合金的应力腐蚀开裂（SCC）。结果表明，裸露的Mg-Al-Zn镁合金对SCC的敏感度较低，在0.15~0.75σ0.2的初始应力载荷下浸泡5天后未发生突然断裂。采用微弧氧化（MAO）涂层，耐腐蚀性能得到增强，但引起更多的表面裂纹，并且当载荷为0.75σ0.2时，可以在腐蚀坑内检测到微裂纹，这与裸合金相似。复合涂层完全避免了SCC和腐蚀。锻造AQ80M合金对SCC的低敏感性应归因于细晶粒尺寸和晶界周围第二相的均匀分布。
Stress corrosion cracking (SCC) of a forged Mg-Al-Zn magnesium alloy with different surface conditions was studied by the four-point bending test and alternate immersion test in NaCl solution. The results showed that the bare Mg-Al-Zn magnesium alloy has low susceptivity to SCC, and no abrupt rupture happened after the immersion test for 5 days under an initial stress load of 0.15–0.75σ0.2. With microarc oxidation (MAO) coating, corrosion resistance was enhanced, but more surface cracks were induced, and microcracks could be detected inside corrosive pits when the load was 0.75σ0.2, which is similar to the bare alloy. The composite coating totally avoided both SCC and corrosion. The low susceptivity of the forged AQ80M alloy to SCC should be attributed to the fine grain size and even distribution of secondary phases around the grain boundary.