**5.2 Welding residual stress distribution**

**Figure 10a–c** displays the 2D mapping of longitudinal welding residual stresses in the middle cross-section computed by the numerical simulation and IFEM, respectively. In detail, **Figure 10a** presents the longitudinal residual stresses without considering back-gouging, **Figure 10b** shows the longitudinal residual stresses with considering back-gouging, and **Figure 10c** illustrates the longitudinal residual stresses by IFEM. It can be seen from the figure that both the longitudinal residual stresses with or without considering back-gouging matched with the measured contour. But, the peak value of longitudinal residual stress with considering backgouging is higher than that without considering back-gouging, which is almost equal to the maximum measured value. Moreover, back-gouging process can reduce

*Residual Stress Evaluation with Contour Method for Thick Butt Welded Joint DOI: http://dx.doi.org/10.5772/intechopen.90409*

#### **Figure 10.**

it can be concluded that the fusion area predicted by FEM with considering

*Fusion zone of butt welded joint: (a) without considering back-gouging; (b) with considering back-gouging.*

in the middle cross-section computed by the numerical simulation and IFEM, respectively. In detail, **Figure 10a** presents the longitudinal residual stresses without considering back-gouging, **Figure 10b** shows the longitudinal residual stresses with considering back-gouging, and **Figure 10c** illustrates the longitudinal residual stresses by IFEM. It can be seen from the figure that both the longitudinal residual stresses with or without considering back-gouging matched with the measured contour. But, the peak value of longitudinal residual stress with considering backgouging is higher than that without considering back-gouging, which is almost equal to the maximum measured value. Moreover, back-gouging process can reduce

**Figure 10a–c** displays the 2D mapping of longitudinal welding residual stresses

back-gouging is reasonable.

**Figure 9.**

**116**

**5.2 Welding residual stress distribution**

*New Challenges in Residual Stress Measurements and Evaluation*

*2D mapping of longitudinal welding residual stress distribution of middle cross-section: (a) without considering back-gouging; (b) with considering back-gouging; (c) IFEM.*

the tensile stress area of main weld. In addition, **Figure 10c** shows some irregularities at the edges of the cut surfaces; these irregularities may be produced due to wire entrance and exit during the specimen cutting.

**Figure 11a–c** quantitatively compares the longitudinal welding residual stress distributions in the middle cross-section along L1, L2, and L3 computed by TEP FE and the corresponding measurements, respectively. It can be seen from the **Figure 11a, b** that the computed longitudinal residual stress distributions along L1 and L2 agree well with the measured stress distribution. It can be seen from **Figure 11c** that the through-thickness longitudinal stresses distribution in center weld was obviously smaller than that in cap welds, which can be increased by backgouging process. Therefore, it can be found that the peak longitudinal stresses were in cap welds and the longitudinal stresses in center weld can be increased by backgouging process.

**Figure 12a, b** displays the features of transverse residual stresses in butt welded joint with or without considering back-gouging, respectively. It can be seen from the picture that the tensile stress is almost constant, while the compressive stress considering back-gouging is greater than that without considering back-gouging. And the middle cross-section mappings show that the signal of transverse residual stresses of local root weld and its distribution are changed obviously. Finally, the

locations of the maximum residual stress and through-thickness spatial distributions provide an indication of the significance of crack initiation and the integrity of

*Residual Stress Evaluation with Contour Method for Thick Butt Welded Joint*

**Figure 13** showed the contour of z-direction welding displacement through TEP FEM and CMM measurement. The maximum z-direction welding displacement by TEP FEM was 0.9363 mm without considering back-gouging and 1.5874 with considering back-gouging, respectively. The maximum z-direction displacement by

*Transverse welding residual stress distribution: (a) without considering back-gouging; (b) with considering*

*Contour of z-direction welding displacement: (a) without considering back-gouging, (b) with considering*

the welded components.

**Figure 12.**

**Figure 13.**

**119**

*back-gouging, and (c) experimental measurement.*

*back-gouging.*

**5.3 Welding displacement**

*DOI: http://dx.doi.org/10.5772/intechopen.90409*

**Figure 11.** *Longitudinal residual stress distributions along L1, L2, and L3.*

*Residual Stress Evaluation with Contour Method for Thick Butt Welded Joint DOI: http://dx.doi.org/10.5772/intechopen.90409*

locations of the maximum residual stress and through-thickness spatial distributions provide an indication of the significance of crack initiation and the integrity of the welded components.
