engleski

Residual stresses measurement of heat treated clad plates applying centre-blind hole drilling and surface layersremoval procedures

The influence of applied clad procedure (hot rolling, SAW by strip electrodes in two beds and explosion welding), as well as heat treatment by annealing on level and nature of residual stresses was researched. The relaxed deformation measurement on clad plate surfaces was performed by applying centre-hole drilling method using special measuring electrical resistance strain gauges (rosettes). The centre hole-drilling method of residual stress measurement used in the present work, involve the drilling of a blind hole into the surface of a component. This changes, locally, the internal stress equilibrium through material removal. The change in local strain state resulting from the hole-drilling is recorded by specially designed strain gauges mounted on the surface, concentrically with the hole, in a 0/ 90 / 225° rosette arrangement. The equipment used for this work is known as the RESTAN (REsidual STress ANalysis) system and was purchased from HBM of Germany. The distribution of residual stresses on cross-section of specimens was determined using surface layer removal procedure. Inside of the base carbon low alloyed steel, the cross section measurement relieved elastic deformation was performed by removing of surface layers using electrical resistant measuring gauge (rosettes) situated on opposite side of layers removal. After performed measuring, size and nature of residual were determined and compared using analytical method. Depending of residual stresses on depth of drilled blind-hole as well as on cross-section removed layers is studied. Knowledge of tensile residual stresses is essentially due to possible appearance of cracking tendency of corrosion resistant steel to stress corrosion, while knowledge of pressured residual stresses is important because of their influence on construction stability.

residual stresses measurement ; heat treated clad plates ; centre-blind holes drilling ; surface layers removal ; electrical resistance strain gauges (rosettes).

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