Arc welded joint and method for manufacturing the same

An arc welded joint manufactured by lap fillet arc welding of joining a corner formed by two steel sheets, the arc welded joint comprising:

• an upper sheet;
• a lower sheet;
• and
• a weld joining the upper sheet and the lower sheet and penetrating into the upper sheet and the lower sheet,
• wherein an upper sheet thickness t1 and a lower sheet thickness t2 are both less than or equal to 5.0 mm;
• the lower sheet thickness t2 and a penetration depth d satisfy the following inequality (1), the penetration depth d being a distance from a boundary between the upper sheet and the lower sheet to a lower surface of a weld bead in a cross-section of the weld:
• 0.2
• ≤
• d
• /
• t
• 2
• ≤
• 0.8
• ,
• (
• 1
• )
• where, in inequality (1), t2 (mm) is lower sheet thickness and d (mm) is penetration depth;
• and
• a slag coverage area ratio SRATIO calculated by the following equation (2) using a bead surface area SBEAD of a weld bead surface and a slag surface area SSLAG is less than or equal to 15%, the slag surface area SSLAG being an area of a region of the bead surface area SBEAD covered with slag:
• S
• RATIO
• =
• S
• SLAG
• /
• S
• BEAD
• ×
• 100
• ,
• (
• 2
• )
• where, in equation (2), SBEAD (mm2) is bead surface area, SSLAG (mm2) is slag surface area being the area of the region covered with slag, and SRATIO (%) is slag coverage area ratio.