Karakteristik Ketangguhan Impact dan Struktur Mikro Shielded Metal Arc Welding (SMAW) Baja ASTM A36

The quality of welded joints is strongly influenced by welding parameters, particularly heat input and electrode type. Variations in these parameters can affect microstructural evolution and the mechanical properties of welded joints. This study investigates the effects of heat input and electrode type on the microstructure and impact toughness of ASTM A36 carbon steel butt joints fabricated using the Shielded Metal Arc Welding (SMAW) process. Three heat input levels, namely 0.91, 1.33, and 1.89 kJ/mm, and two electrode types, E7018 and E6013, were investigated. The welding current, voltage, and travel speed were maintained at the same levels for both electrode types. Microstructural characterization was conducted in the heat-affected zone (HAZ) and weld metal using optical microscopy, while impact toughness was evaluated using the Charpy impact test. The results indicate that variations in heat input and electrode type significantly affect the microstructural characteristics of both the HAZ and weld metal. At a heat input of 0.91 kJ/mm, the weld metal produced using both electrode types was predominantly characterized by an acicular ferrite microstructure. The Charpy impact test results revealed that increasing the welding heat input tended to reduce the impact toughness of the welded joints. The highest impact toughness of 26.43 J was obtained using the E7018 electrode at a heat input of 0.91 kJ/mm, whereas the lowest value of 18.60 J was obtained using the E6013 electrode at a heat input of 1.89 kJ/mm.