Study of Inherent Strain Distribution needed for High Quality System of Welded Structure

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This paper deals with the distribution of inherent strain dominating high quality of welded structure. Firstly, measurements of inherent strain generated in a butt joint and a bead on plate have been made by the sequential removal of layers. It is shown from experiments that the distribution of inherent strain in a bead on plate is almost the same as one in a butt joint. The rise of average temperature, which is derived from similar law of themal conductivity and is calculated from welding conditions and plate sizes, is useful for arranging the distribution of inherent strain. The plate length does not affect the distribution of inherent strain on the center plane of plate length, when the plate length is above one and half times as long as the width of welded plate.Second, measurements of heat input generated in the plate cut by a laser cutting and a plasma cutting have been made for investigating a predictive equation. The heat input by cutting is called as the residual energy in the cutting field and is important factor for controlling the deformation generated through a thermal cutting process. The total energy needed for the thermal cutting was studied by many researchers and the predictive equation of the total energy was proposed by Wells. However the equation predicting the residual energy was not studied. The equation for the residual energy is derived from modifying Wells equation. By comparing the experimental data with the predicted values, it is shown that the proposed equation is applicable to the evaluation of the residual energy.