非破坏性测试 用中子衍射测定残余应力的标准试验方法

[中文适用范围]： 本文件描述了通过中子衍射测定多晶材料中残余应力的测试方法。 它适用于均质和非均质材料，包括含有不同相的材料。 概述了中子衍射技术的原理。 提供了以下方面的建议： ——选择合适的衍射晶格平面，对不同类别的材料进行测量， — 进行测量的样本方向，以及 — 相对于材料颗粒进行检查的材料体积尺寸和预期的应力状态。 描述了在中子束中精确定位和对准测试件以及精确定义单独测量所采样的材料体积的程序。 描述了校准中子衍射仪器所需的预防措施。 介绍了获得无压力参考的技术。 详细描述了通过中子衍射进行单独测量的方法。 介绍了分析结果和确定其统计相关性的程序。 就如何根据应变数据确定残余应力的可靠估计以及如何估计结果的不确定性提供了建议。 [外文原描述]： This document describes the test method for determining residual stresses in polycrystalline materials by neutron diffraction. It is applicable to both homogeneous and inhomogeneous materials including those containing distinct phases. The principles of the neutron diffraction technique are outlined. Suggestions are provided on : — the selection of appropriate diffracting lattice planes on which measurements should be made for different categories of materials, — the specimen directions in which the measurements should be performed, and — the volume of material examined in relation to the material grain size and the envisaged stress state. Procedures are described for accurately positioning and aligning test pieces in a neutron beam and for precisely defining the volume of material sampled for the individual measurements. The precautions needed for calibrating neutron diffraction instruments are described. Techniques for obtaining a stress-free reference are presented. The methods of making individual measurements by neutron diffraction are described in detail. Procedures for analysing the results and for determining their statistical relevance are presented. Advice is provided on how to determine reliable estimates of residual stresses from the strain data and on how to estimate the uncertainty in the results.