坑蚀钢筋二次拉伸力学性能试验研究

Experimental Study on Mechanical Properties of Pit Corrosion of Steel Bars under Secondary Loading

通过机械制缺模拟自然环境中钢筋不同程度的坑蚀,研究坑蚀程度对钢筋二次受力时强度与伸长率等力学性能的影响规律.结果表明:坑蚀钢筋一次或二次拉伸时,随坑蚀深度增加,塑性变形性能下降,名义抗拉强度降低,但实际抗拉强度有所提高;对于加载到强化段卸载的坑蚀钢筋在二次加载时无明显的屈服平台,经历时效硬化后,屈服平台将会重现,且二次名义屈服强度较一次加载时有所提高.时效硬化的时长与坑蚀程度无明显关系;坑蚀钢筋二次受力时伸长率随坑蚀深度以及时效天数的增加而减小,其中坑蚀深度对伸长率的影响更加显著.

The effect of degree of pit corrosion on mechanical properties such as strength and elongation of steel bars under the secondary loading is studied.The study is carried out by simulating different degree of pit corrosion of steel bars in natural environment through mechanical defects.The results indicate that when the pit corroded steel bars are stretched once or twice,the plastic deformation performance decreases gradually.The nominal tensile strength decreases but the actual tensile strength increases with the increase of the depth of corrosion spot;The pit corroded steel bars are unloaded when the load reaches its reinforcement service stage.The yield platform is not obvious during the secondary loading.The yielding platform will reappear and the secondary nominal yield strength is improved after age hardening compared to the once loading.The relationship between the duration of age hardening and the degree of pit corrosion is not obvious;The elongation of the pit corroded steel bars decreases with the increase of the depth of corrosion spot and aging time under the secondary loading,the effect of the depth of corrosion spot on elongation is more obvious.