Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample
Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample
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DOI：
10.1088/0957-0233/22/6/065705
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发表时间：
2011-06
影响因子：
2.4
通讯作者：
J. Rebelo Kornmeier;J. Gibmeier;M. Hofmann
中科院分区：
文献类型：
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作者：
J. Rebelo Kornmeier;J. Gibmeier;M. Hofmann
中子应变测量在表面是至关重要的。当靠近样品表面扫描时，由于几何和发散效应，会出现像差峰位移。这些像差峰位移可以是与残余应变相关的峰位移相同的量级。在这项研究中，它将被证明，通过优化的Si（400）单色器的水平弯曲半径，像差峰位移的表面效应可以大大减少。细晶粒结构钢S690QL的无应力样品被用来找到最佳的仪器条件，以尽量减少像差峰位移。采用优化后的Si（4 0 0）单色仪和仪器设置测量了SAE 4140钢喷丸试样的残余应力深度梯度，验证了该方法的有效性。的残余应力深度分布是在良好的协议，从国际循环测试（BRITE-EURAM-项目ENSPED）的X射线衍射测量得到的结果。结果打开非常有前途的可能性，桥梁之间的差距差距的X射线衍射和传统的中子衍射的非破坏性残余应力分析接近表面。
Neutron strain measurements are critical at the surface. When scanning close to a sample surface, aberration peak shifts arise due to geometrical and divergence effects. These aberration peak shifts can be of the same order as the peak shifts related to residual strains. In this study it will be demonstrated that by optimizing the horizontal bending radius of a Si (4 0 0) monochromator, the aberration peak shifts from surface effects can be strongly reduced. A stress-free sample of fine-grained construction steel, S690QL, was used to find the optimal instrumental conditions to minimize aberration peak shifts. The optimized Si (4 0 0) monochromator and instrument settings were then applied to measure the residual stress depth gradient of a shot-peened SAE 4140 steel sample to validate the effectiveness of the approach. The residual stress depth profile is in good agreement with results obtained by x-ray diffraction measurements from an international round robin test (BRITE-EURAM-project ENSPED). The results open very promising possibilities to bridge the gap between x-ray diffraction and conventional neutron diffraction for non-destructive residual stress analysis close to surfaces.