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Residual stresses that occur during the welding process, are the main cause of failure and defects in welded structures. This paper, presents the use of an electronic processing laser speckle interferometer to measure the residual stress of a welded pipe for a nuclear power plant. A tensile testing machine was used to evaluate a welded pipe that failed in compression. The inform plane deformation and modulus of elasticity of the base metal and welds were measured using an interferometer. Varying the load on the welded pipe had a larger effect on the deformation of the base metal the other properties of the base metal and welds. The elastic moduli of the base metal and weld of the welded pipe were 202.46 and 212.14 GPa, respectively, the residual stress was measured to be 6.29 MPa.

Electronic speckle pattern interferometry (ESPI) is a very useful method for measuring in-plane surface displacement. Using the cw-laser and image-processing system, it is possible to measure displacement and strain. Unlike traditional strain gauges or the moire method, the ESPI method requires no special surface preparation or attachments and can measure in-plane displacement with no contact and in real time. In this experiment, a specimen was loaded in parallel with a load cell, which provided loading step. The specimen was a flat plate or a plate with a 12 mm-diameter hole in its center. Strain gauges were attached to the specimen in x and y directions. This study provides an example of how ESPI has been used to measure two-dimensional displacement and strain distribution in this specimen. The results measured by ESPI are comparable with the data which were obtained by the strain-gauge method in tensile testing in the 1-ton range

In recent years, Laser Speckle Pattern Interferometry(SPI) and its development have enabled surface deformation of structure components and materials to be accurately examined. SPI is a very useful method for measuring in-plane components of displacement. In measuring thermal expansion coefficient, the various problems are occurred, and the measuring limitation is existed. In this study, INCONEL 601 and Tantalum were used as specimen material. Specimens were heated to the high temperature(1000 °C) by electric current.