PSI - Issue 41

Paolo Ferro et al. / Procedia Structural Integrity 41 (2022) 430–438 Paolo Ferro et al. / Structural Integrity Procedia 00 (2019) 000–000

432

3

forming laminated products (5 mm thick) (Fig. 1a) and subsequent welding of adjacent edges (Fig. 1b). Single square groove and a combination of Gas Tungsten Arc Welding (GTAW) with Plasma Arc Welding (PAW) were adopted according to the schematic in Fig. 2.

a

b

Fig. 1. Pipe forming (a) and welding (b)

Table 1. Alloy nominal chemical composition Element Ni Cr Fe Mo

Nb

C

Mn

Si

P

S

Al

Ti

Co

%

��

58,0 min

5,0 max

20,0- 23,0

8,0 - 10,0

3,15 4,25

0,10 max

0,50 max

0,50 max

0,0015 max

0,0015 max

0,40 max

0,40 max

1,0 max

Fig. 2. Schematic of welding technique adopted in the experiments

Process parameters are collected in Table 2.

Table 2. Welding process parameters. Filler metal used in GTAW: IN625

Shielding gas flux (It/min)

Welding speed (cm/min)

Interpass temperature (°C)

Heat input (KJ/cm)

Process

Current (A)

Voltage (V)

DC – EN 190 DC – EN 235

1° PAW

29.5

30

11.56

2 5%

Ar 95% +H

150°C

18÷22

2° GTAW

16.5

30

8.00

Short-term (20 min) induction annealing heat treatments, followed by water quenching, were carried out at