PSI - Issue 13

Ali Waqas et al. / Procedia Structural Integrity 13 (2018) 2065–2070 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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and arc extinguishing areas as compared to the steady stage, finally, resulting in termination of further deposition of layers. This phenomenon has been controlled by controlling the parameters including current, voltage and travel speed to obtain uniform height throughout the bead so that as many layers can be deposited as required. Schematic is shown in Fig. 1(a). In the current study, impact toughness at room temperature of the resulting material is analyzed in direction parallel and to the direction perpendicular to the deposition direction. The specimens have been taken from different regions of the thin wall in both directions. An automatic impact testing machine with additional digital output display has been used having the maximum capacity of 300 J of impact absorption energy with an impact velocity of 5.2 m/s and hammer pre-lift angle of 150 o depicted in Fig. 1(b).

Fig. 1. (a) Schematic of robotic assisted welded thin wall with important areas and the direction of specimen extraction; (b) Charpy Impact testing machine with digital output display and control.

As the structure made is a thin wall structure so the sample for Charpy impact test could not be made of standard size. So sub-size specimens having dimensions 55x10x5 mm were cut in both the directions, 5 samples in parallel and 5 in perpendicular to the deposition direction. The specimen is according to ASTM E23 sub-size specifications of notched bar impact testing of metallic materials Fig. 2. Energy absorbed along with the lateral expansion and shear fraction has been studied. Brinell hardness test was performed of each sample and is related to the impact results. Moreover, metallography was performed to analyze the microstructure of the specimens and after the fracture, fractography in both directions has been performed to check the mode of fracture.

Fig. 2. (a-b) Sub-size sample cut for experiment. (c) Placement of sample and impact direction (d) Dimensions according to ASTM E23 standard.

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