随机点蚀对Q550E钢试件抗拉力学性能的影响

Influence of Stochastic Pitting Corrosion on Tensile Mechanical Performance of Q550E Steel Specimen

为了研究点蚀对高性能钢力学性能退化的影响,基于3D扫描对锈蚀Q550E钢试件的表面形貌指标进行数据采集,获取了试件蚀坑深度数据和概率密度函数,以及锈坑平均深度、深度标准差与质量锈蚀率之间的关系。在此基础上,考虑试件均匀锈蚀,提出了基于实测点蚀统计数据建立随机点蚀模型的方法,模拟得到了Q550E钢随机点蚀试件荷载-位移曲线。利用现有试验结果验证了有限元模型的计算精度,分析了点蚀位置和深度对极限强度和最大变形的影响,讨论了极限载荷与最大横截面损失率之间的关系。结果表明:锈蚀高性能钢试件蚀坑深度值服从对数正态分布,随着锈蚀率的增加,锈坑深度方差和均值会逐渐增大,且两者与锈蚀率分别呈现出线性和幂函数关系;同一点蚀强度下,试件蚀坑平均深度和方差分别增加20%,试件极限强度和极限荷载平均值分别减少5%和2%,试件极限强度变异性随着蚀坑平均深度增加而增大,而不会随着其深度方差的变化产生明显改变;在蚀坑大小相同的情况下,蚀坑位置对试件最大变形影响强于对极限强度的影响;极限荷载随着最大横截面损失率的增加呈线性递减;同一点蚀强度下,试件极限强度和变形会随着试件长宽比的增加而减小,试件厚度会对变形有一定影响。

In order to study the influence of pitting corrosion on mechanical performance degradation of high performance steel,the data of surface morphology indicators of corroded Q550E steel specimens are collected with 3D scanning,the data of corroded pit depth and probability density function of the specimens are obtained,and the relationship among the average depth,standard deviation of depth and quality corrosion rate of corroded pits are obtained.On this basis,considering the even corrosion of the specimens,the method of establishing stochastic pitting corrosion model based on the measured statistical data of pitting corrosion is proposed,and the load-displacement curve of stochastic pitting corroded specimens of Q550E steel is simulated.The calculation precision of the finite element model is verified with the existing test result,the influences of the pitting corrosion position and depth on the ultimate strength and maximum deformation are analyzed,and the relationship between ultimate load and maximum cross-section loss rate is discussed.The result shows that(1)the pit depth values of corroded high performance steel specimens follow lognormal distribution,the variance and mean value of corroded pit depth increase gradually with the increase of corrosion rate,and they show linear and power function relationships with corrosion rate respectively;(2)under the same pitting corrosion strength,the average depth and variance of corroded pits of specimens increase by 20%respectively,the average values of ultimate strength and load decrease by 5%and 2%respectively,and the ultimate strength variability increases with the increase of average depth of the corroded pits without significant change with the change of its depth variance;(3)under the condition of the same corroded pit size,the influence of corroded pit position on the maximum deformation is more than on the ultimate strength;(4)the ultimate load decreases linearly with the increase of loss rate of maximum cross-section;(5)under the same pitting corrosion strength,the ultimate strength and deformation of specimens decrease with the increase of the length-width ratio,and the deformation is affected by the thickness of the specimens.