Polychromatic X-ray method for residual-stress measurements in a subsurface layer
The classical sin2ψ method with characteristic X-rays is widely used to measure residual stress nondestructively in the steel members of a structure or a machine. With this method it is, however, difficult to measure the three-dimensional stress distribution with a steep gradient that occurs along the depth direction in a subsurface layer of the material after surface treatment such as grinding or cold rolling. This paper presents a new polychromatic X-ray method for residual-stress measurements in a subsurface layer. The relationship between the diffracted beam peak of the polychromatic X-ray and the strain along the depth direction in a subsurface layer was obtained by theoretical analysis. It was modeled by numerical simulation to obtain probable values of the parameters, and these were used along with experimental X-ray data to derive an experimental value for the stress gradient. This was compared with the values predicted from plate bending theory.
KeywordsFluid Dynamics Theoretical Analysis Stress Distribution Surface Treatment Cold Rolling
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