MEASUREMENT OF RESIDUAL STRESSES BY THE NEUTRON DIFFRACTION TECHNIQUE IN A WELDED JOINT
Résumé
The welds are the site of high residual stresses, localized in the vicinity of the weld cracks. Their presence caused many type of damage modes as stress corrosion, fatigue, sudden failure and increasing the temperature of ductile-brittle transition. Residual stresses in restrained welds and weld repairs are very complex. The heat treatment affects the value and distribution of residual stresses in the specimen. This peak stress in all three samples occurred not at the toe, but in the middle of the weld bead, where the yield stress is higher. The transverse residual stresses of around half the maximum value of longitudinal stress have been observed. The use of the neutron diffraction (ND) technique for residual stress measurements is described. In addition, studies of macrostructure and hardness were conducted. The results of different tests conclude the influence of heat treatment on residual stresses in welds.
Références
[2] Hausild, P., 2002. Ductile-brittle transition in a low alloy steel,thesis of doctorate, central School of bets.
[3] Lamberd, P. A., 2001. Rupture by cleavage of microstructure of bainitic steels obtained in conditions of welding, thesis of doctorate, ENS of the Mines of Paris.
[4] Lu, X. Y., 2002. Influence of Residual Stress on Fatigue Failure of Welded Joint. Faculty of N of Paris orth Carolina State University.
[5] Zaoui, M., Bouchoucha, A, 2008. Influence of heat treatment on brittle fracture welding crds of constructionnal steels. World Journal of Engineering 5(2), 34-40.
[6] Anne-Sophie., B.2007. Estimating the risk of brittle fracture of welds of pipelines in high-grade steels: characterization and modeling , ENSMP of Paris.
[7] Gaffard, V, 2004. Experimental study and modelling of high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steel weldments, ENSEEG of Paris.
[8] Tanguy, B, 2001. Modeling of the Charpy test by the local approach of the rupture, application to the case of steel 16MND5 in the field of transition. ENS of Paris.
[9] Barsoum, Z, 2008. Residual Stress Analysis and Fatigue Assessment of Welded Steel Structures. School of Engineering Sciences, Stockholm, Sweden.
[10] Withers, P.J., Bhadeshia H.K., 2001, Residual Stress –I: Measurement Techniques, Materials Science & Techn.17, 355-365.
