## 3 Results
### The Welding Sequence Layout and the Thermal Cycles  
The welding sequence layout (Figure 1) seems to play an important role in the distribution of secondary austenite and \(\sigma\)-phase. A larger amount and concentration of secondary austenite was found for a larger number of subsequent passes in the immediate vicinity of a specific weld pass. The same trend was seen for the preferred location for \(\sigma\)-phase formation. In the FR experiment, Weld Pass 7 was the only one with three weld passes in the immediate vicinity and it was the one experiencing the longest reheating time in the different critical temperature ranges studied: 20 s for \(\mathrm{v}_{2}\) formation, 7 s for nitrides formation, and 5 s for \(\sigma\)-phase formation. Similarly, in the GR experiment, Weld Passes 4 and 6, both experiencing reheating caused by three subsequent weld passes showed the second longest reheating time in the critical ranges of temperatures: 23 s for \(\mathrm{v}_{2}\) formation, 6 s for nitrides formation, and 6 s for \(\sigma\)-phase formation. In the GR experiment, the weld pass experiencing longer reheating times was the root pass: 40 s for \(\mathrm{v}_{2}\) formation, 8 s for nitrides formation, and 9 s for \(\sigma\)-phase formation. In the GH experiment, the maximum number of subsequent neighboring passes was 2, and the root pass was by far the one experiencing the longest reheating time in the critical temperature ranges: 98 s for \(\mathrm{v}_{2}\) formation, 13 s for nitride formation, and 16 s for \(\sigma\)-phase formation.  
None of the weld passes in the experiments was at any time in the temperature ranges for the dissolution of \(\sigma\)-phase or nitrides, so dissolution of these phases was not expected.  
When comparing the magnitude of the influence of the subsequent weld passes on one deposited pass, the time that the pass was exposed to higher than 500 \({}^{\circ}\)C was taken as a reference. The reason is that the formation of the intragranular secondary austenite (\(\mathrm{v}_{2}\)) was assumed to happen at temperatures higher than 500 \({}^{\circ}\)C [2; 18], and as described in Section 2.4, it is the lowest temperature in the formation of the secondary phases considered. For the FR experiment, only the subsequent deposited passes in direct contact with the pass investigated had an influence (exposure time between 4 and 15 s to T \(>\) 500 \({}^{\circ}\)C). Interestingly, in the GR experiment, the two subsequent deposited passes had an influence (exposure times between 1 and 24 s to T \(>\) 500 \({}^{\circ}\)C) until Weld Pass 8, which was only influenced by Weld Pass 9 and not by Weld Pass 10 because of the welding layout (Figure 1). In the GR experiment, the root pass was influenced by the three subsequent deposited passes (exposure times between 26 and 44 s). These results were in agreement with the measured cooling rates (Figure 7): the slower  
Figure 14: Micrographs from the GR welds showing the microstructure of Weld Pass 1 (GTAW Root). **(Left)** Massive amounts of nitrides in the ferrite grains in the as-deposited condition. **(Center)** Secondary austenite formation in the ferrite grains after reheated caused by Weld Pass 2. **(Right)** The \(\sigma\)-phase after six reheats.  
the cooling rate, the more time the pass was exposed to T > 500 \({}^{\circ}\)C, and more previously deposited passes were influenced.