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Research on Durability Estimation for Steel Buildings

钢结构建筑耐久性评估研究

基本信息

批准号：
16560511
负责人：
MIMURA Hiroaki
金额：
$ 2.3万
依托单位：
Tokyo Denki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560511/
关键词：
steel structure durability stress corrosion cracking crack propagation artificial corrosion-test

项目摘要

This study showed that stress-corrosion-cracking behaviors and yield and/or tension strength after corrosion environmental loading. Used steels were SUS304 austenitic stainless steel, SMA490B weather proof steel for welding structure and SN490B rolled steel for building structure. Corrosion conditions were 2 hours spray of acid-rain contain 5% salts, 4 hours dray with 60□ temperature, 20% humidity and 2 hours full-humidity using artificial environmental testing apparatus. Those conditions were loaded cyclically with 650 times for stress-corrosion-test and 200 times for statically tension test.The results of stress-corrosion-cracking-test were as follows,(1)For SUS304, stress-corrosion-crack did not occurred until 650 corrosion cycles, but Luders band grew in front of the crack tip and the Luders band propagated according to the corrosion cycles. Consider the Luders band to be the crack, stress-corrosion-cracking threshold for SUS304 was 25.3-26.2 MN/m^<3/2> for base metal, 24.2-25.0 MN/m^<3/2> for heat affected zone respectively.(2)For SMA490B, stress-corrosion-crack did not occurred until 85 corrosion cycles too, and for this steel, rust formative rate was faster than stress corrosion crack propagation rate. It was thought that the rust layer of steel surface prevented the stress corrosion crack propagation. So that, the stress corrosion cracks hardly occurred for weather proof steel.(3)The surface of steel plate had bumpy condition by the corrosion. The bumpy conditions of SN490B were more remarkably than that of SMA490B weather proof steel. So that yield and/or tension strength of steels after corrosion deteriorated very much on account of the stress concentration by bumpy conditions.

研究表明，在腐蚀环境载荷作用下，钢的应力腐蚀开裂行为以及屈服和/或抗拉强度。所用钢为SUS304奥氏体不锈钢，焊接结构用SMA490B耐候钢，建筑结构用SN490B轧钢。腐蚀条件为含5%盐的酸雨喷雾2小时，60℃烘干4小时，湿度20%，人工环境试验仪全湿2小时。循环加载650次应力腐蚀试验和200次静态拉伸试验。应力腐蚀开裂试验结果表明：(1)SUS304材料在650次腐蚀循环后才出现应力腐蚀裂纹，但裂纹尖端前方有Luders带生长，Luders带随腐蚀循环次数的增加而扩展。以Luders带为裂纹，SUS304钢的应力腐蚀开裂门槛值母材为25.3-26.2MN/m~(-1)，热影响区为24.2-25.0MN/m~(-1)，热影响区为24.2-25.0MN/m~(-1)。(2)对于SMA490B，也是在85次腐蚀循环后才出现应力腐蚀-裂纹，且锈蚀速率快于应力腐蚀裂纹扩展速率。认为钢表面的锈层阻止了应力腐蚀裂纹的扩展。因此，耐候钢几乎不会产生应力腐蚀裂纹。(3)钢板表面因腐蚀而出现凹凸不平的情况。SN490B的颠簸情况比SMA490B耐候钢更为显著。因此，由于凹凸不平的应力集中，腐蚀后的钢的屈服和/或抗拉强度大大恶化。