Residual stresses may be generated in target structural material used in accelerator-driven transmutation. Calibration curves were developed for transmutation target structural materials using positron annihilation spectroscopic (PAS) method. These calibration curves consisted of different line shape parameters (S, T & W) determined by the PAS method on martensitic stainless steel as a function of tensile stress/strain imparted to cylindrical specimens. This paper presents a comparative analysis of residual stresses in these specimens as a function of (S, T & W) determined by the PAS technique. The resultant data showed a consistent pattern in these parameters versus applied stresses ranging between the Yield and the Ultimate tensile strength.
Residual stresses may be generated in target structural material used in accelerator-driven transmutation due to plastic deformation. Nondestructive positron annihilation spectroscopic (PAS) method has been used to estimate residual stresses in candidate structural materials such as martensitic Alloy EP-823 and Alloy HT-9. Different line shape parameters (S, W & T) obtained from the PAS measurements have been related to the degree of cold deformation. The results indicate that the magnitude of S parameter was enhanced at the intermediate level of cold deformation followed by an almost identical S value at the highest level of cold reduction. Conversely, the T parameter was reduced at higher level of cold deformation. The evaluation of the cold-worked specimens by transmission electron microscopy revealed the presence of dislocations, as expected.
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