Soyama Hitoshi, Kuji Chieko, Kuriyagawa Tsunemoto, Chighizola Christopher R, Hill Michael R
Department of Finemechanics, Tohoku University, Sendai 980-8579, Japan.
Department of Mechanical Systems Engineering, Tohoku University, Sendai 980-8579, Japan.
Materials (Basel). 2021 May 24;14(11):2772. doi: 10.3390/ma14112772.
As the fatigue strength of metallic components may be affected by residual stress variation at small length scales, an evaluation method for studying residual stress at sub-mm scale is needed. The sin method using X-ray diffraction (XRD) is a common method to measure residual stress. However, this method has a lower limit on length scale. In the present study, a method using at a 2D XRD detector with -oscillation is proposed, and the measured residual stress obtained by the 2D method is compared to results obtained from the sin method and the slitting method. The results show that the 2D method can evaluate residual stress in areas with a diameter of 0.2 mm or less in a stainless steel with average grain size of 7 μm. The 2D method was further applied to assess residual stress in the stainless steel after treatment by laser cavitation peening (LCP). The diameter of the laser spot used for LCP was about 0.5 mm, and the stainless steel was treated with evenly spaced laser spots at 4 pulses/mm. The 2D method revealed fluctuations of LCP-induced residual stress at sub-mm scale that are consistent with fluctuations in the height of the peened surface.
由于金属部件的疲劳强度可能会受到小长度尺度下残余应力变化的影响，因此需要一种研究亚毫米尺度残余应力的评估方法。使用X射线衍射（XRD）的sin方法是测量残余应力的常用方法。然而，该方法在长度尺度上有下限。在本研究中，提出了一种使用带θ振荡的二维XRD探测器的方法，并将二维方法测得的残余应力与sin方法和切口法得到的结果进行比较。结果表明，二维方法可以评估平均晶粒尺寸为7μm的不锈钢中直径为0.2mm或更小区域的残余应力。二维方法进一步应用于评估激光空化喷丸（LCP）处理后的不锈钢中的残余应力。用于LCP的激光光斑直径约为0.5mm，不锈钢以4脉冲/mm的均匀间隔激光光斑进行处理。二维方法揭示了亚毫米尺度下LCP诱导残余应力的波动，这与喷丸表面高度的波动一致。
