PSI - Issue 14

P D Gosavi et al. / Procedia Structural Integrity 14 (2019) 304–313

307

P D Gosavi et al./ Structural Integrity Procedia 00 (2018) 000 – 000

2.4. Weld metal chemical analysis

Weld metal chemical analysis was carried out using Direct Reading Spectroscopy (DRS) for determining the content of alloying elements, micro alloying elements and impurities using Ametek spectromaxx machine. The carbon equivalent (Pcm) was then calculated from the elemental analysis of the different joints. 2.5. Metallographic preparation and microscopy analysis The specimen extracted for metallographic study was subjected to grinding with 220, 400, 600 and 800 grid papers and thereafter polished with diamond paste of 0.5 µm size. The polished specimens were etched with freshly prepared 2% Nital solution. Quantitative metallography was carried out to determine the micro constituents like acicular ferrite and grain boundary ferrite in weld. The microstructural multiphase analysis was carried out using an image analyzer attached with the optical microscope (Make: Carl Zeiss, M2M microscope). 2.6. Tensile testing Tensile testing was performed using all weld specimens. The tensile specimens were extracted from top and bottom grooves of the weld, schematically shown in fig.2. Weld metal tensile properties were carried out using round shape tensile specimens with gauge diameter (d) of 6 mm and gauge length 30mm following ASTM E8M standard. An electromechanical controlled universal testing machine (Make: Instron5985, 250kN) was used to perform testing at room temperature at a extension rate of 2 mm/min.

(b)

(a)

Fig.2. (a) Location of tensile specimen in weld coupon; (b) Tensile specimen (Gauge Dia.6mm)

2.7. Charpy impact testing

The impact specimens were machined within 2-3 mm from plate surface from each of the V groove of the weld coupon so that uniformity is maintained about location for all the specimens, as schematically shown in fig.3. Impact toughness was determined following ASTM E23 standard using impact machine (Make: Tinius Olsen, Capacity: 400J). Total 20 numbers of standard size specimens 10 × 10 × 55 mm were extracted from each of the welded coupons and tested at different test temperatures (300, 00,-200,-400,-600,-800 C) to determine ductile to brittle transition temperature (DBTT).

Fig.3. Location of charpy specimen extracted from weld coupon