PSI - Issue 11

Hizadora Constanza Medina D’Ambros et al. / Procedia Structural Integrity 11 (2018) 114–121 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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The damage caused by this pathologies in the steel were measured by an experimental investigations with weld joint samples intentionally welded with the same identified pathology previously created with materials equals to those l used in the water elevated reservoir.

2. Experimental investigation

All of the butt-welded specimens were fabricated from hot-roll ASTM A36 structural steel with 6,3mm thickness. The chemical compositions allowing manufacturer's technical catalog is 0,25% of carbon (C), 0,040% of phosphorus (P), 0,050% of sulfur (S) and 0,4% of silicon (Si) (USIMINAS, 2017). The NBR 6892-1: 2013 (ABNT, 2013) indicate spec imens of proportional size to tensile test because of the plate’s thickness above 3mm. The Equation 1 determines length of steel plate where O L = original measurement length; k = coefficient of proportionality (5.65); O S = original cross-sectional area. (1) The length of steel plate for the samples of proportional size was 90mm and a steel plate length of 30mm was request by the test machine. To determine the steel yield strength and steel ultimate tensile strength of the base metal four plates without weld and size 150x40x6.3 mm were used. The damages in weld joint were simulated in thirty-six samples, four plates for each weld damage: high welding amperage (E-HIGH), low welding amperage (E-LOW), slag inclusions (E-SLAG), moist welding electrodes (E MOIST) and four samples to weld joint reference (E-REF). Plates with size 150x40x6.3 mm with a single V-groove joint between them were used to make a finished weldment of size 75x40x6.3 mm. The Fig. 4 presents the dimensional details of the specimen used in the experiments and welding parameters. O O L k S 

Fig. 4. Dimensional detail of samples used in the experiment: base metal samples and butt-welded samples.

The welding process was SMAW. The E7018 coated electrode of 4mm conserved free of moisture was used, except for E-MOIST sample. The electric current used on butt-welded specimens varied according to sample: 175 A for E-REF, E-SLAG and E-MOIST; 230 A for E-HIGH ; 100 A for E-LOW. For this, a welding machine with rated electric current of 280 A and apparent power of 27.5 KVA was used, the base metal was not heat to welding process, the ambient temperature was between 40 to 42°C. The base metal tensile strength and the butt-welded specimen tensile strength were measure by tensile test according with NBR 6892-1: 2013 (ABNT, 2013). In these tests, a hydraulic pressure machine with load limit capacity of 1000 kN was used.