PSI - Issue 42

Mihai A. Popescu et al. / Procedia Structural Integrity 42 (2022) 1626–1633 M.A. Popescu et al. / Structural Integrity Procedia 00 (2022) 000–000

1629

4

Table 3. Chemical composition of the wire electrodes. Element

Specimen 1 [%]

Specimen 2 [%]

C

0.11 1.04 0.21

0.1 1.7 0.3

Mn

Si

P S

0.011 0.009

0.01

0.006 0.004

Cu Ni Cr Mo

0.1

0.002

- - -

0.05 0.01

Fig. 2. Locations of Vickers Hardness test indentations.

2.2. Vickers Hardness test

Once the microstructure and macrostructure images were registered, the Vickers Hardness test was performed using an Wolpert-Werke Dia Testor 2 Rc universal hardness testing machine with a pyramid diamond tip; a 10 kg gravity mass acting at a loading time of approximately 20 s. The same specimens were used for the Vickers Hardness test and the locations of the indentations is shown in Fig. 5.

2.3. The Contour Method

The Contour Method (Prime and DeWald (2013)) was chosen for the residual stress measurements. For this measurements, part of the initial specimens were reduced in size in order to be cut via Electric Discharge Machining (EDM). From S1 a 250 mm x 250 mm x 59 mm was extracted, while a larger 600 mm x 400 mm x 59 mm specimen was obtained from S2. For the second specimen, extracted from S2, the dimensions were larger and the cut was performed between two pilot holes as per the method described by Jacob et al. (2018).

2.4. Charpy Impact test

For the Charpy impact test, V-notch specimens were extracted, as per ISO 15614-1:2017, EN ISO 9016:2012, and EN ISO 148-1:2016, from the weld metal (WM) and HAZ. Because of the configuration and thickness of the welds an extra set of samples had to be extracted from the weld root, both from the WM and HAZ. The specimens were given the designations shown in Table 4 in order to be easily identifiable, specimens designated as A are extracted from S1 and B from S2. The tests were performed at a temperature of -20°C ( ± 2°C) for both sets of specimens in order to have a valid comparison. The specimens were cooled via a gaseous medium with pressurized liquid nitrogen (LN2) using a suitable laboratory device to homogenize the temperature of the gas stream. Besides these tests, an additional set of A-type specimens were produced and tested at lowered temperatures.