X線的残留応力解析における重み付き平均解析法の実験検討(<小特集>X線材料強度小特集)

概要

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The purpose of this study was to test the weighted averaging method experimentally. A plane lapping of an annealed bearing steel SUJ-2 generated a steep gradient of residual stress within its shallow surface layer. X-ray strain measurements on the lapped and successive electropolished surfaces revealed that the strain ε_ψ was not linearly dependent on sin^2ψ, but curved parabolically on sin^2ψ diagram independent of the measured directions. It was also found that the stresses calculated on the peak positions or medians of half width of diffraction profiles began to deviate clearly from those calculated from the centroid positions when the stress gradient was larger than 2-3 kg/mm^2/ μm. The weighted averaging method gave a residual stress pattern continuously distributing from the surface to depth when the principal stress σ_3 was considered to exist in the direction normal to te surface within the X-ray penetrating depth. The experimental plots on sin2ip diagram showed that the strain free direction ψ^* deviated from sin^2ψ = 2ν/(1+ν) appropriate for the state of plane stress, depending on the sign and magnitude of σ_3. This means that the tri-axial stress analysis must be considered when the mechanically deformed surfaces such as lapped, polished. cut and round are treated.
社団法人日本材料学会の論文
1981-03-15