ABSTRACT The residual stress may greatly vary through thickness due to the large temperature gradients and severe plastic deformation in depth for thick section friction stir welded plates. AA 2024-T351 plates with 6.5, 12 and 20 mm thicknesses were joined by friction stir welding to investigate the differences of residual stress variations with depth between thin and thick plates. The surface residual stresses were compared between the X-ray diffraction and contour measurements. Significant variations of stress peaks, root central residual stresses and widths of ‘M’ profiles were observed along the thickness for thick plates. The origins of the aggravated variations with depth were investigated from the temperature gradients and material flow variations through thickness.

中文翻译：

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不同厚度搅拌摩擦焊铝板残余应力随深度变化的研究

摘要 由于大的温度梯度和厚截面搅拌摩擦焊板在深度上的严重塑性变形，残余应力可能随厚度变化很大。AA 2024-T351 厚度为 6.5、12 和 20 mm 的板通过搅拌摩擦焊连接，以研究薄板和厚板之间残余应力随深度变化的差异。在 X 射线衍射和轮廓测量之间比较了表面残余应力。对于厚板，沿厚度观察到应力峰值、根部中心残余应力和“M”型材宽度的显着变化。从温度梯度和材料流动随厚度的变化研究了随深度变化加剧的起源。