Positron Annihilation in Steel Burnished by Vibratory Shot Peening
R. Zaleskia and K. Zaleskib
aInstitute of Physics, Maria Curie-Skłodowska University, pl. Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland
bFaculty of Mechanical Engineering, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland
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Received: 5 06 2006;
A series of C45 steel samples was burnished by shot peening with varying time of treatment. The samples were investigated by nondestructive positron annihilation techniques: angular correlations of two-quantum annihilation radiation and positron annihilation lifetime spectroscopy. To determine residual stresses present under burnished surface the same samples were studied by destructive Davidenkov method. Change of absolute value of the weighted average of residual stresses over positron range in the series of the samples is in good agreement with change of S/W ratio obtained by angular correlations of two-quantum annihilation radiation. Both parameters increase during first 10 minutes of shot peening and then stabilize. Positron annihilation lifetime spectra allowed to identify two types of structural defects: smaller ones like vacancies or dislocations and bigger - probably clusters of vacancies. Increase in shot peening time causes reduction of positron trapping rate and lifetime rise in bigger defects.
DOI: 10.12693/APhysPolA.110.739
PACS numbers: 78.70.Bj, 71.60.+z, 62.20.Fe, 62.20.Mk, 81.20.Wk, 81.40.-z, 81.70.-q, 81.05.Bx