盐雾腐蚀对HRB400E抗震钢筋低周疲劳和力学性能的影响

摘要：采用质量分数为5%的NaCl溶液在盐雾腐蚀箱进行30~90d加速腐蚀试验，研究了盐雾腐蚀对HRB400E钢筋低周疲劳行为和拉伸性能的影响。然后采用轴向位移控制模拟地震载荷对腐蚀钢筋开展了低周疲劳和拉伸试验，获得循环响应特征曲线和应变 寿命曲线。结合SEM断口形貌观察，分析钢筋的低周疲劳断裂机制。结果表明：盐雾腐蚀对钢筋的质量和尺寸有明显影响，钢筋表面产生腐蚀坑；钢筋的力学性能随腐蚀时间增加而降低，腐蚀90d的断裂伸长率下降率达461%，屈服强度在腐蚀30d以后可能就不再满足标准要求；腐蚀明显削弱了钢筋的抗循环载荷性能，导致低周疲劳寿命下降；腐蚀会减小钢筋的裂纹扩展区面积并加速裂纹扩展。

Effects of salt spray corrosion on low cycle fatigue behavior and mechanical properties of HRB400E steel bar

Accelerated corrosion tests were carried out in salt spray corrosion chamber with 5% NaCl solution for 30-90 days to study the effect of salt spray corrosion on low cycle fatigue behavior and tensile properties of HRB400E steel bars. Low cycle fatigue and tensile tests were carried out on corroded steel bars under simulated earthquake load controlled by axial displacement, and the cyclic response characteristic curve and strain life curve were obtained. Combined with SEM fracture morphology observation, the low cycle fatigue fracture mechanism of steel bar was analyzed. The results show that the salt spray corrosion has obvious influence on the quality and size of steel bars, and corrosion pits appear on the surface of steel bars. The mechanical properties of steel bars decrease with the increasing of corrosion time. The elongation at break decreases by 461% after 90 days of corrosion. The yield strength may no longer meet the standard requirements after 30 days of corrosion. The results show that the corrosion weakens the cyclic load resistance of the steel bars and leads to the decrease of the low cycle fatigue life; the corrosion reduces the area of the crack propagation zone and accelerates the crack propagation.