【摘要】 利用非线性超声表面波检测技术实现了对304奥氏体不锈钢点蚀损伤的无损表征。将固溶态304奥氏体不锈钢在质量分数为6.0%,10.0%,14.0%的FeCl₃溶液中,分别浸泡6,12,18h。利用OLS4000激光共聚焦显微镜对浸泡试样进行表面形貌的观察、稳态点蚀孔三维形貌以及尺寸的测量,利用RAM-5000测量超声表面波非线性系数,基于蚀孔微观形貌和尺寸变化分析点蚀损伤的非线性系数变化规律。结果表明:归一化非线性系数随超声表面波传播距离的增加而逐渐增大;表面波传播距离一定时,归一化非线性系数随浸泡时间的延长和溶液质量分数的升高而单调递增。超声波与点蚀引起的材料不连续界面相互作用,造成界面间的应力-应变非线性效应,且非线性效应随点蚀损伤的加剧被累积,这一结论对奥氏体不锈钢点蚀研究具有较大的参考价值。更多还原

【Abstract】 The nondestructive characterization of pitting corrosion of 304 austenitic stainless sheets of steel is realized by nonlinear ultrasonic surface wave detection technique.The solid solution 304 austenitic stainless sheets of steel are soaked in the FeCl3 of 6.0%,10.0% and 14.0%for 6,12,and 18 hrespectively.The surface morphology of the samples soaked is observed by OLS4000 laser confocal microscope,and the three-dimensional morphology and size of the steady-state pitting holes are measured.The nonlinear coefficient of the ultrasonic surface wave is measured by RAM-5000.The normalized nonlinear coefficient is analyzed based on the morphology and dimensional change of the pits.The results show that the normalized nonlinear coefficient rises gradually with the increasing ultrasonic surface wave spreading distance.When the surface wave spreading distance is constant,the normalized nonlinear coefficient is significantly increased with the increase of soaking time and the mass fraction of the solution.It is concluded that the stress-strain nonlinear effect resulted from the interaction of ultrasonic wave and discontinuous interface around pits tends to be remarkable with the increasingly serious pitting damage.更多还原