中子衍射在残余应力分析中的应用

中子衍射应力测量原理基于布拉格方程，通过取样测量体积内样品晶格的晶面间距进行精确表征，获取材料微观晶格的形变信息，可以实现晶体材料深层内部弹性应变的直接无损测量。测量值通常与样品测量位置和外加温度或力学载荷相关，用于评估实际部件整体结构和变形参数。本研究介绍中子衍射的基本原理，辊压法调控搅拌摩擦焊的残余应力和变形、管道焊接残余应力、大尺寸工程部件、近表面材料的残余应力测量分析、低温下飞机组件材料、原位热处理焊接材料，以及热老化和蠕变过程中内应力定量分析等典型应用案例。

Applications of Neutron Diffraction in Residual Stress Analysis

The principle of residual stress measurement using neutron diffraction is based on Bragg’s Law.Through accurate characterization of the crystal plane spacing within the gauge volume,information about the material’s micro lattice deformation can be obtained,thus the deep internal elastic strain of the crystalline material can be measured non-destructively.Usually the measurement value is related to the location of the measurement,temperature and external loading,which is then used for the evaluation of structural integrity and deformation of the actual component.Based on the authors’previous research experiences,this paper briefly introduces the basic principles of neutron diffraction and subsequently focuses on its applications in residual stress analysis in a number of typical case studies,including rolling to reduce residual stress and distortion in friction stir welds,UOE linepipe seam welds,pipe girth welds,large engineering component,near surface residual stress analysis,residual stresses at cruising altitude temperature,stress response of a welding material during in-situ heat treatment,and quantitative analysis of internal stress during thermal ageing and creep.