The Comparison of Tensile Strength and Macrostructure of SMAW Welds with Single V- and Double V-Grooves on ASTM A36 Steel

Abstract

The 25 mm thick ASTM A36 steel requires efficient SMAW. This study presents a descriptive comparison of Single V and Double V grooves using E7018 Ø3.2 mm. Welding current 93-132 A, voltage 20-24 V, travel speed 90-130 mm/min (HI 0.85-1.52 kJ/mm), interpass max 150°C. Single V 17 passes, Double V 12 passes. Transverse weld tensile test geometry per ASTM E8, procedure per ASME IX QW-150 (n=2 per variation). Macro examination per ASTM E3/E407 (n=1 per variation, indicative). Base metal UTS tested 478 MPa. Results: Double V showed mean UTS 577.0 MPa, SD 1.41 MPa, fracture in weld metal, HAZ indicative width 2.1 mm, no defect observed in macro specimen. Single V showed mean 512.5 MPa, SD 62.93 MPa, HAZ indicative width 3.4 mm, porosity observed in separate macro specimen. The lower UTS in one Single V specimen is hypothesized to be associated with discontinuity. Due to n=2, inferential statistics were not performed. Double V showed more consistent UTS and fewer passes under this WPS. Base metal UTS 478 MPa was within ASTM A36 range 400-550 MPa. All tensile fractures occurred in weld metal, consistent with overmatched E7018 weld metal (510-610 MPa) per AWS A5.1.