Inference of Plastic Deformation in Welding Residual Stress Field from Infrared Thermography

Abstract

Plastic deformation near a crack takes an important role relating to the failure or the fracture of the structure. In the present paper, a nondestructive and noncontact technique for evaluation of the plastic region near a crack by using infrared thermography is proposed. The temperature rise of specimen surface near a crack in weldment is measured by the infrared thermography. It is assumed that the heated region by the work of plastic deformation corresponds to the plastic zone near a crack. The effect of the welding residual stress on the shape and dimensions of the heated region is examined in the present study. The temperature rise and the heated region are compared with the plastic deformation obtained by the elasto-plastic finite element analysis. In addition, the usefulness and the limitations of the application of infrared thermography to the evaluation of the plastic region are discussed.