In stress measurement using indentation technique, the value of stress was calculated by the difference in load with and without residual stress. Even in the measurement of asymmetric stress filed using asymmetric indenter such as Knoop indenter, the reference load without residual stress was required for calculating the existing residual stress. However, it takes a lot of work to apply stress measurement of the part with hardness change due to mechanical machining or welding-induced phase transformati...
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Semi-nondestructive Measurement of Asymmetric Residual Stress Field using Indentation Technique without Reference Load

This study presents an advanced method to estimate mechanical properties of structural steels through the instrumented indentation techniques using spherical indenter. Finite element analysis model of instrumented indentation testing was constructed to investigate the effect of stress.strain curve of materials on the indentation load.depth curve and the indentation contact radius. From calculation results, new estimation formulae for the representative stress and stain relations were established. Meanwhile,...
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An Advanced Method to Estimate Mechanical Properties of Structural Steels through Instrumented Spherical Indentation Techniques

Considering the effect of the complex phenomena during the welding, for example thermal deformation, phase transformation, residual stress, etc, is important when the welding process is used. All of the effects are caused by heat input and conduction during the welding. Therefore, evaluating the heat input and conduction properties during the welding is so important in order to understand and control the phenomena. However, the weld pool has a fluid flow with thermal conduction, a free surface, and an ...
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Study for Evaluation of Temperature Field during Welding using Particle Method

Abstract Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by acc...
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Prediction method of long-term reliability in improving residual stresses by means of surface finishing

In the present study, a semi-destructive method for estimating the mechanical properties, including plastic strain, of materials was developed using the instrumental indentation technique (IIT). The formula for estimating plastic strain was derived using true stress-true strain curves that were measured by IIT. The developed method requires only one parameter, namely, the work hardening coefficient, for estimating the plastic strain of pre-strained materials. The usefulness of the developed method was ...
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Study on Evaluation Method of Plastic Damage using an Indentation Technique for Degradation Diagnosis of Steel Structures

It is known that weld distortion has negative influence on structure integrity. Therefore, it is important for ensuring structure strength and reliability to control weld distortion appropriately. Especially, development of various countermeasures against weld distortion is desirable for emergent repair work in large-scale accident such as earthquakes. As one of useful countermeasure against angular distortion, in-process control welding with reverse-side heating was proposed however validation of the ...
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Study on Shape Regulation Technique of Weld Structure for Good Quality Control