**4.1. Welding simulations and temperature distributions**

First, thermal profile produced during welding as the heat source travels is presented as shown in Fig. 10. Fig. 10 represents the thermal profiles on several selected nodes along one fillet weld taken from WS-1 simulation results. It was shown that heat was moving as the welding heat source travelled. This can also be seen from the high temperature of the next adjacent node when the previous node has achieved its peak temperature. In addition, the next adjacent node's peak temperature was higher than that of the previous one, which also indicated that heat was accumulated. Subsequently, it has been distributed through the welding structure and the heat release to the surroundings was due to convective heat transfer.

**Figure 10.** Thermal profiles on several selected nodes along the fillet weld.

Figs. 11 - 14 illustrate the welding simulation showing the peak temperature for each welding sequence and the temperature distribution after welding towards the room temperature. From the temperature distributions, it is clear that the peak temperature achieved in the welding was greatly affected by the welding sequence. The welding sequences produced different interaction between the current step and the accumulation of heat carried out from the previous steps due to the sequential path followed.

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With the finite element procedures described in the previous section, results on the problem considered are presented in this section. The finite element simulation for all the variation of welding was completed in 45 load-steps (LS). During the number of load-steps, the welding process took for 40 load-steps, while the cooling one took for the rest of the LS. For the presentation of welding simulation, the results of the LS which respectively represent the conditions of the peak temperature and the beginning of cooling processes were taken and plotted. Note that the temperature went down towards the reference (room) temperature after the LS of 41. Accordingly, the longitudinal and transverse residual stresses and the

First, thermal profile produced during welding as the heat source travels is presented as shown in Fig. 10. Fig. 10 represents the thermal profiles on several selected nodes along one fillet weld taken from WS-1 simulation results. It was shown that heat was moving as the welding heat source travelled. This can also be seen from the high temperature of the next adjacent node when the previous node has achieved its peak temperature. In addition, the next adjacent node's peak temperature was higher than that of the previous one, which also indicated that heat was accumulated. Subsequently, it has been distributed through the welding structure and the heat release to the surroundings was due to convective heat

distortions occurred due to the welding sequences were presented and discussed.

**4.1. Welding simulations and temperature distributions** 

**Figure 10.** Thermal profiles on several selected nodes along the fillet weld.

heat carried out from the previous steps due to the sequential path followed.

Figs. 11 - 14 illustrate the welding simulation showing the peak temperature for each welding sequence and the temperature distribution after welding towards the room temperature. From the temperature distributions, it is clear that the peak temperature achieved in the welding was greatly affected by the welding sequence. The welding sequences produced different interaction between the current step and the accumulation of

**4. Results and discussion** 

transfer.

**Figure 11.** The welding simulation for WS-1: (a) the peak temperature achieved at the LS of 40, and (b) the temperature distribution after the welding process at the LS of 41.

**Figure 12.** The welding simulation for WS-2: (a) the peak temperature achieved at the LS of 40, and (b) the temperature distribution after the welding process at the LS of 41.

**Figure 13.** The welding simulation for WS-3: (a) the peak temperature achieved at the LS of 30, and (b) the temperature distribution after the welding process at the LS of 41.

3D Finite Element Simulation of T-Joint Fillet Weld:

The peak temperature difference between WS [K]

Effect of Various Welding Sequences on the Residual Stresses and Distortions 599

Table 1 describes further the peak temperature achieved in a WS and the peak temperature difference between WS, in which the smallest and largest peak temperature differences

Moreover, it may be also interesting to note how the peak temperature achieved in a WS may be related to the corresponding residual stresses and angular distortions produced.

> The peak temperature achieved [K]

4 40 2928 - 3 30 2849 79 1 40 2756 93 2 40 2376 380

Fig. 16 and 17 shows respectively the simulated distributions of longitudinal and transverse residual stresses for each welding sequence investigated in this study. It is seen from Fig. 16 and 17, the maximum values of the longitudinal and transverse residual stresses occurred in the weld bead region for all the welding sequences. Note also that the distribution of the

It can be seen that the smallest longitudinal and transverse residual stresses occurred in WS-2. It is interesting to note that the welding sequence also had the lowest peak temperature as indicated in Table 1. Also, for longitudinal residual stresses, their distributions due to the welding sequences tend to be similar. For transverse ones, the distributions were different. It seems that for the later, it could be related to the way of the

between WS were 79 and 552 K, respectively.

**4. 2. Residual stress distributions** 

welding had been performed.

Load-step (LS)

**Table 1.** The peak temperature achieved for each welding sequence.

residual stresses produced from each of the welding sequences.

Welding sequence (WS)

**Figure 14.** The welding simulation for WS-4: (a) the peak temperature achieved at the LS of 40, and (b) the temperature distribution after the welding process at the LS of 41.

The peak temperature achieved for each welding sequence as well as the peak temperature difference between WS were summarized in Table 1, in which the highest peak temperature of 2928 K belongs to WS-4 having the highest heat accumulation at the end of the welding process. The shapes of the temperature profile at the fillet welds during welding were depicted in Fig. 15.

From Fig. 15, it can be seen the differences of the temperature profile at the fillet welds during different WS. It is interesting to note that in general the temperature profiles of WS-1 and WS-2 tend to be similar. In a less extent, it also happened for those of WS-3 and WS-4, as the peak temperature of WS-3 was achieved at the LS of 30. Nevertheless, the peak temperature achieved was very different, even for the WS having similar temperature profiles such as WS-1 and WS-2. This verified again that the peak temperature achieved in the welding was greatly affected by the welding sequence.

**Figure 15.** Peak temperature for each welding sequence.

Table 1 describes further the peak temperature achieved in a WS and the peak temperature difference between WS, in which the smallest and largest peak temperature differences between WS were 79 and 552 K, respectively.

Moreover, it may be also interesting to note how the peak temperature achieved in a WS may be related to the corresponding residual stresses and angular distortions produced.


**Table 1.** The peak temperature achieved for each welding sequence.

### **4. 2. Residual stress distributions**

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depicted in Fig. 15.

**Figure 14.** The welding simulation for WS-4: (a) the peak temperature achieved at the LS of 40, and (b)

The peak temperature achieved for each welding sequence as well as the peak temperature difference between WS were summarized in Table 1, in which the highest peak temperature of 2928 K belongs to WS-4 having the highest heat accumulation at the end of the welding process. The shapes of the temperature profile at the fillet welds during welding were

From Fig. 15, it can be seen the differences of the temperature profile at the fillet welds during different WS. It is interesting to note that in general the temperature profiles of WS-1 and WS-2 tend to be similar. In a less extent, it also happened for those of WS-3 and WS-4, as the peak temperature of WS-3 was achieved at the LS of 30. Nevertheless, the peak temperature achieved was very different, even for the WS having similar temperature profiles such as WS-1 and WS-2. This verified again that the peak temperature achieved in

the temperature distribution after the welding process at the LS of 41.

the welding was greatly affected by the welding sequence.

**Figure 15.** Peak temperature for each welding sequence.

Fig. 16 and 17 shows respectively the simulated distributions of longitudinal and transverse residual stresses for each welding sequence investigated in this study. It is seen from Fig. 16 and 17, the maximum values of the longitudinal and transverse residual stresses occurred in the weld bead region for all the welding sequences. Note also that the distribution of the residual stresses produced from each of the welding sequences.

It can be seen that the smallest longitudinal and transverse residual stresses occurred in WS-2. It is interesting to note that the welding sequence also had the lowest peak temperature as indicated in Table 1. Also, for longitudinal residual stresses, their distributions due to the welding sequences tend to be similar. For transverse ones, the distributions were different. It seems that for the later, it could be related to the way of the welding had been performed.

3D Finite Element Simulation of T-Joint Fillet Weld:

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Fig. 18 describes the transverse residual stress distribution along the fillet weld for each WS. The maximum values of longitudinal and transverse stresses as well as von Mises stress for each welding sequence were summarized in Table 2. The ratio between the longitudinal and the transverse residual stress values for the problem considered varies from 1. 06 to 1. 22.

**Figure 18.** Distribution of transverse residual stress along the fillet weld for each welding sequence.

The maximum longitudinal stress value [MPa]

respect to the welding sequences.

Welding sequence (WS)

Observing further Fig. 18, it is also interesting to note the consistency of trends of the transverse residual stresses distributions produced by the WS simulated in the present study. It can be clearly observed that the distributions of transverse residual stresses produced by WS-3 and WS-4 and WS-1 and WS-2, respectively, are in consistent nature with

2 240 197 117 4 283 266 251 3 292 257 249 1 298 250 250

**Table 2.** The maximum longitudinal and transverse stress values for each welding sequence.

The maximum transverse stress value [MPa]

The maximum von Mises stress value [MPa]

**Figure 16.** Simulated distributions of longitudinal residual stresses for: (a) WS-1, (b) WS-2, (c) WS-3, and (d) WS-4.

**Figure 17.** Simulated distributions of transverse residual stresses for: (a) WS-1, (b) WS-2, (c) WS-3, and (d) WS-4.

Fig. 18 describes the transverse residual stress distribution along the fillet weld for each WS. The maximum values of longitudinal and transverse stresses as well as von Mises stress for each welding sequence were summarized in Table 2. The ratio between the longitudinal and the transverse residual stress values for the problem considered varies from 1. 06 to 1. 22.

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and (d) WS-4.

(d) WS-4.

**Figure 16.** Simulated distributions of longitudinal residual stresses for: (a) WS-1, (b) WS-2, (c) WS-3,

**Figure 17.** Simulated distributions of transverse residual stresses for: (a) WS-1, (b) WS-2, (c) WS-3, and

**Figure 18.** Distribution of transverse residual stress along the fillet weld for each welding sequence.

Observing further Fig. 18, it is also interesting to note the consistency of trends of the transverse residual stresses distributions produced by the WS simulated in the present study. It can be clearly observed that the distributions of transverse residual stresses produced by WS-3 and WS-4 and WS-1 and WS-2, respectively, are in consistent nature with respect to the welding sequences.


**Table 2.** The maximum longitudinal and transverse stress values for each welding sequence.
