1996 Volume 14 Issue 4 Pages 762-767
The recently proposed method based on the inherent strain theory has proved to have better accuracy than those traditional methods proposed by Stablein, Daridenkov et al. Some layer removal methods tend to produce additional strain or stress in specimen which leads to estimated residual stress error. In the first part of this work, the inherent strains near the machined surface of a mild steel specimen, produced respectively by fraise milling, shaping, electric spark machining and emery paper wet-polishing, were examined. In the second part of this work, electropolishing, wet-polishing and fraise milling were employed to measure the residual stress distribution in a clad plate respectively. The following conclusions are obtained:
(1) Electric spark machining can not be used as a layer removal method. The heat produced in the machining not only introduces additional inherent strain in the near-surface, but also tends to change the original inherent strain distribution through a large thickness into the specimen.
(2) Fraise milling and shaping produce large additional inherent strains which lead to large estimation error. These methods can be used only when the mechanically strained layer is furtherly removed by electro-polishing or wet-polishing.
(3) Wet-polishing by emery paper produces only a negligible inherent strain and therefore is a reliable method for layerremoval like electro-polishing.
