喷丸镍基合金材料微区残余应力的切槽法测量研究

本文结合聚焦离子束-电子束(Focused ion beam-electron beam,简称FIB-EB)双束系统和真空镀膜工艺,进行微区散斑的制备工艺研究,并将所发展的微散斑制备工艺应用于喷丸镍基合金材料表面制斑,进而结合切槽法进行残余应力高温释放规律的测量研究。在FIB-EB双束系统下记录切槽前后制斑微区的图像,利用数字图像相关法计算切槽后的位移,结合InglisMuskhelishvili理论公式可计算得到残余应力。文中研究了不同温度及保温时间对残余应力释放的影响规律。结果表明,残余应力随保温时间的增长释放速度逐渐减小,最后残余应力趋于稳定值。同时,温度越高,残余应力释放越彻底,800℃下近乎完全释放。该工艺具有适用性好,效率高等优点,可望在材料微区变形测量中得到进一步应用。

On the Micro-Residual Stress Measurement of Shot Peened Nickel-Based Alloy Material by using Slot-Milling Method

In this paper,based on FIB-EB (Focused ion beam-electron beam) dual beam system and vacuum coating technique,the preparation technology of micro-speckle pattern was improved first.Then,this self-developed technique was successfully utilized to prepare micro-speckle patterns on the surface of shot peened nickel-base alloy material.Further,combining slotting milling method,the measurement of residual stress release at high temperature was studied.Using FIB-EB dual beam system,the micro-speckle patterns are recorded before and after the milling,then the digital image correlation method was used to calculate the displacement after the milling.Based on InglisMuskhelishvili theory,the residual stress can be calculated.In this paper,the influence of different temperatures and different temperature holding time on the release of residual stress were also studied.Results indicate that the releasing speed of residual stress decreases with the increase of holding time,and finally tends to a steady value.In addition,the higher the temperature is,the more thorough the residual stress release.The residual stress is almost completely released at 800℃.From obtained results,it is conclude that the proposed speckle fabrication technique has advantages of good applicability and high efficiency,and is expected to have further application in micro-deformation measurement.