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工程实际中,建筑用钢不可避免地会接触空气而遭受氧化腐蚀。本文开展了地震区域大力推广应用的HRB400EIII级钢筋氧化前、后的低周疲劳行为研究。采用轴向应变控制方法,在MTS809拉扭复合疲劳试验机上开展了大量的低周疲劳试验,获得了氧化前、后HRB400EIII级钢筋低周疲劳性能,如循环应力响应特征、循环应力-应变关系以及寿命预测公式等。通过断口电镜扫描发现,氧化后HRB400EIII级钢筋的裂纹均萌生于试件表面,且存在多处裂纹源。研究结果表明,氧化腐蚀对低周疲劳寿命及微观断裂机理方面均存在明显影响,并从力学性能变化的角度对引起差异的原因进行了解释。
In engineering practice, steel for construction will inevitably come into contact with air and suffer oxidative corrosion. In this paper, the research on the low cycle fatigue behavior of HRB400EIII steel bars before and after oxidation promoted in the earthquake area is carried out. Using axial strain control, a large number of low cycle fatigue tests were carried out on the MTS809 tensile and torsion composite fatigue testing machine to obtain the low cycle fatigue properties of HRB400EIII steel bars before and after oxidation, such as cyclic stress response characteristics, cyclic stress-strain relationship and Life expectancy formula and so on. Scanning electron microscopy (SEM) revealed that the cracks of HRB400EIII steel after oxidation were all initiated on the surface of the specimen, and there were many sources of cracks. The results show that oxidation corrosion has a significant effect on the low cycle fatigue life and microscopic fracture mechanism, and explains the reasons for the difference from the perspective of mechanical properties.