Abstract: Provided are an arc welded joint and an arc welding method. The arc welded joint has a slag-coverage area ratio SRATIO (%) of 15% or less, and a weld bead width ratio WRATIO (%) of 60% or more. The SRATIO is calculated by using an equation SRATIO=100×SSLAG/SBEAD. In this equation, an area of a surface of a weld bead formed by performing arc welding on a steel sheet is defined as a weld bead surface area SBEAD (mm2) and, of the weld bead surface area SBEAD, an area of a region covered with slag is defined as a slag surface area SSLAG (mm2). The WRATIO is calculated by using an equation WRATIO=100×WMIN/WMAX from a maximum value WMAX (mm) and a minimum value WMIN (mm) of a weld bead width in a direction perpendicular to a welding line of the weld bead.

Abstract: A MIG welding method for carbon steels using an Ar shielding gas. The method includes short-circuiting a welding wire and a base material. The average short-circuiting frequency in welding is 20 Hz to 300 Hz and the maximum short-circuiting period is 1.5 s or less.