PSI - Issue 13

Mihaela Iordachescu et al. / Procedia Structural Integrity 13 (2018) 554–559 M. Iordachescu, A. Valiente, E. Scutelnicu/ Structural Integrity Procedia 00 (2018) 000–000

556

3

adequate preparation of the borders, to ensure the complete penetration of the molten filler metal at the T-root. The repair entailed transforming the resulted misconfiguration that produced the incomplete penetration defect. As shown in Fig. 1b, the weld metal was mechanically removed from one side of the joint until the welded metal of the other side was reached. Then, the complete filling of the gap thus formed, followed .

Fig. 1. a) Structural detail showing the analyzed welded joints and the location of testing specimens; b) sketch of detected defect and the configurations of the repaired vs. the initial design of the welded joints

Doubts emerged about the contribution of the new developed joint configuration (from now on referred to as the repaired weld, RW) to the overall structure deformability. In order to obtain the tensile and fracture specimens necessary to evaluate the effectiveness of the repairing procedure, structural details reproducing the initial weld design (referred to as the designed weld, NW) and repaired defective joints were made in a specialized workshop. Then, sub size tensile cylindrical specimens, of 3 mm diameter, and standard CT specimens, of thickness B=17.5 mm and width W=40 mm, were manufactured. Both types of specimens (cylindrical and CT) were extracted with the load direction parallel to the column axis (perpendicular to the welded joints). The ligament of CT specimens was positioned to propitiate HAZ cracking on reinforcing plate side. Fig. 3a and Fig. 3b show the backside of two CT specimens, with the former containing a RW and the latter a NW. In addition, tensile and CT specimens with the same dimensions and orientation previously described were extracted for comparison from the base metal (BM) of the HEA profile. Fig. 1a shows he specimens’ location on the structural detail sketch.

Fig. 2. CT specimens with the ligament contained into the HAZ of: a) repaired weld, RW; b) designed weld, NW; c) Stress-strain curves of the tensile tested specimens (E - elastic modulus, R p0.2 - yield strength, R m - tensile strength, m – maximum uniform deformation); d) Load – COD records of the tested CTs The tensile tests were performed on sets of four specimens extracted from the BM and the structural details containing NW and RW; a conventional extensometer of 12.5 mm gage length was used for the elongation measurements. The results are summarized in Fig. 2c in which only one plot of each set of stress-strain curves was depicted (in engineering and true values). The only stress-strain curve that belongs to a homogeneous material is that of BM, because those characterizing the overall mechanical behavior across the NW or RW joints include besides BM