PSI - Issue 54

T. Koščo et al. / Procedia Structural Integrity 54 (2024) 514 – 520 Koščo T., Chmelko V. / Structural Integrity Procedia 00 (2019) 000 – 000

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The main disadvantage of this approach is that the resulting diagrams are only partial diagrams. In most cases, sufficiently large portion of plastic part of the diagram is present to estimate the tensile strength. On the other hand, exact values of ductility or fracture strain are available only in the fracture location. However, obtained data is sufficient for most engineering applications. Figure 8 shows the results from six chosen locations in the WM and HAZ. Results clearly document the difference in material properties between the face of the weld and the weld root. Also, the change of the properties between the weld toe and weld root along the HAZ. Interestingly, tensile diagram of the WM at the weld face location is almost the same as the BM diagram (Fig. 3). But WM properties in the weld root are significantly different (yield stress of at least 600MPa, see Fig. 8). Another important quantity to estimate is the Poisson’s ratio. Here, arises a problem with noise in DIC data. By dividing two noisy data sets, resulting Poisson’s ratio data is extremely noisy. This effect occurs especially by small strain values in elastic region, where is relatively small signal to noise ratio. Therefore, longitudinal and transverse strains were exported as an average value from larger portion of the strain field to lower the noise effects. Hence, Poisson’s ratio has been evaluated in fewer locations. Figure 9 and Figure 10 show the relation between the true tensile diagram and the Poissons ratio curve for base metal, heat affected zone, and weld metal evaluated from specimen 2. Noisy data from elastic region has been deleted and replaced by its average (shown by a red ring in Fig 9 and Fig. 10).

Fig 9. True tensile diagrams and Poissons ratio (a) Base metal (b) Heat affected zone

Fig 10. True tensile diagrams and Poissons ratio of Weld metal