PSI - Issue 75

Carolina Payares-Asprino et al. / Procedia Structural Integrity 75 (2025) 489–500 C. Payares-Asprino et al./ Structural Integrity Procedia (2025)

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input of 0.53 kJ/mm increase by 2.5 %. However, a rise of 54% of heat input to 1.16 kJ/mm decreased residual stress by 122%, reporting compressive stress of -46 MPa. The results show that the maximum residual stress exists in the HAZ, and the residual stress value decreases gradually while the zone is farther from the weld center at base metal are consistent with the finding by Ref [Zhongyin et al. (2011)].Results also show a decrease in tensile residual stress (TRS) in the HAZ of the weld, which transforms into compressive residual stress (CRS), removing the weld bead through the milling process in the HAZ as can be seen in Figure 10. a).

230

223

200 250

175

100 150

115

-50 0 50

-4

23

0

Residual Stress (MPa)

5.1

8.9

Machined Weld Bead Weld Bead

Fig. 9 Residual stress for the weld bead and the machined weld bead in the weld (FZ), HAZ at 5.1 mm and base metal (BM) at 8.9 mm from the center of the weld using HI 0f 1.44kJ/mm.

Weld Bead Machined Weld Bead

a)

Weld Bead Machine Weld Bead

b)

30 55 80

100 150 200 250

-70 -45 -20 5

-100 -50 0 50

0.51

1.16

1.41

0.51

1.16

1.41

Residual Stress (MPa)

Residual Stress (MPa)

Heat Input (kJ/mm)

Heat Input (kJ/mm)

Fig.10 Residual Stress in the weld and machine weld bead of DSS manufactured at 0.53 kJ/mm, 1.16 kJ/mm, and 1.44 kJ/mm: a) HAZ and b) Base Metal

3.2. Fatigue Results Duplex Stainless Steel (DSS) joints are required for the construction of engineering structures. However, the DSS welds are under complex thermal recycles, which results in a severe imbalance of the phase ratio of Ferrite/Austenite and distortion of grain patterns. Consequently, the DSS weld joints are always the weakest link to threaten the structure integrity of those engineering components, particularly in circumstances related to fatigue that are highly susceptible to the microstructure characteristics [Xie et al. (2020]. As can be seen in Figures 9 and 10, the welding procedure created tensile residual stress due to the irregular heat distribution in the DSS weld bead [Alipooramirabad et al. (2017)]. As can be seen in Figure 11, the fatigue lifetimes of weld joints at different heat inputs were shorter than DSS base metal for the same cyclic amplitude, as shown in Figure 11. This is because the specimens containing weldments are stronger but less ductile than the base material