**4. Weld residual stress relaxation after cutting processes**

In order to install mega-welded strucutres such as bridges, off-shores and so on, welding is carried out in the workshop and cutting processes are usually applied. This cutting process is determined depending on the exigences for edge detail and the application Barzoum et *al*. [11] and Cicero et *al*. [12]. The most techniques used for cutting are machine cutting and thermal cutting processes. Moreover, there are additional cutting techniques that has recentrly recognized such as plasma, laser and waterjet. For welded structures, component or specimen a cutting process will introduce relaxation of residual stresses. A few studies emphasized the re-distribution of

*Residual Stresses Distribution Posterior to Welding and Cutting Processes DOI: http://dx.doi.org/10.5772/intechopen.100610*

the welding residual stresses caused by the cutting process [13, 14, 15]. An analysis of data presented in Liang et *al*. [15] was performed. The used material is Q355B with yield strength *σfy* ¼ 359 MPa. The RS was measured using sectioning relaxation strain gauges.

In order to measure the RS in different weld seam lengths, step-by-step sectioning with measurement of the relaxation stress was performed. Residual stresses in specimens with widths vary between 30 mm and 160 mm were measured. In order to better analyze the data, the magnitude of the residual stresses is normalized with the yield strength of the material (*σfy*), and the length was normalized by the plate width (*w*). The following conclusions were extracted:

For longitudinal residual stresses:


For transversal residual stresses:


**Figure 3.** *Plate width as a function of the normalized measured length of CRS after cutting.*

#### **Figure 4.**

*Measured RS along the weld seam length after cutting, Liang et al. [15].*

• Similar to the longitudinal RS, the magnitude of transversal RS decreases gradually with the decrease of the weld seam length (after cutting took place), (See **Figure 3**). In **Figure 3**, *l* is the length where CRS was measured.
