A fillet arc welded joint formed by fillet arc welding at least two metal members, comprising a remelted and solidified portion obtained by irradiating a laser at a weld toe portion of the fillet arc welding of at least one metal member and a region including a boundary of the heat affected zone caused by the fillet arc welding at the surface of that metal member, the remelted and solidified portion being a range from a surface of the metal member to a depth of or less of the thickness of that metal member, an average effective crystal grain diameter of prior austenite at a heat affected zone from a boundary of the remelted and solidified portion at the surface of the metal member to a depth of 0.1 mm in the thickness direction of the metal member being 20 m or less.

An arc welding process is disclosed. In one example, the process comprises arranging an electrode at the front of a joining gap formed by joining partners contacted with opposite poles to the electrode; arranging a pair of magnetic poles at the rear or top of the joining gap and substantially centered with respect to the front electrode surface; generating the arc such that the joining partners form a welding zone comprising a weld pool with substantially simultaneous induction of a low-frequency oscillating magnetic field between the pair of magnetic poles; progressively moving the electrode along the joining gap to move the weld pool between the joining partners, leaving behind a weld seam, with synchronous entrainment of the low-frequency oscillating magnetic field. A magnetic flux density of the low-frequency oscillating magnetic field is selected such that an induced Lorentz force supports the weld pool and prevents escape from the joining gap.

A clad pipe includes: a first tubular member formed of first metal or alloy; a second tubular member provided on an inner circumferential surface of the first tubular member, and formed of a second metal or alloy of a different type from the first metal or alloy, a thickness of the second tubular member in a radial direction being at least 50 m; and an anchor layer formed on a boundary surface where the first tubular member and the second tubular member are in contact with each other, wherein a material of one of the first and the second tubular members digs into a material of another tubular member in the anchor layer.

A clad pipe includes: a first tubular member formed of first metal or alloy; a second tubular member provided on an inner circumferential surface of the first tubular member, and formed of a second metal or alloy of a different type from the first metal or alloy, a thickness of the second tubular member in a radial direction being at least 50 m; and an anchor layer formed on a boundary surface where the first tubular member and the second tubular member are in contact with each other, wherein a material of one of the first and the second tubular members digs into a material of another tubular member in the anchor layer.

A bead structure for non-pressure mark welding, which is applied to panels for joining a plurality of overlapped panels through projection welding may include a plurality of beads which protrude in the same direction toward an upper portion by pressing the panel disposed in a lower portion among the overlapped panels, and when center points of the beads are connected by a straight line, the beads are disposed to be distanced from each other at a predetermined to form a triangle.

A welding system that, using a junction at which a standing plate and a bottom plate meet as a welding line, makes an electrode weave centered on the welding line and thereby welds along the welding line. In this welding system, control is performed such that the arc voltage at a standing-plate-side weaving edge is equal to or less than the arc voltage at a welding-line center position, such that the arc voltage at a bottom-plate-side weaving edge becomes equal to or greater than the arc voltage at the welding-line center position, and such that the arc voltage at the standing-plate-side weaving edge becomes lower than the arc voltage at the bottom-plate-side weaving edge. The system can suppress occurrence of inferior bead appearance and of welding defects in horizontal fillet welding.

A welding system that, using a junction at which a standing plate and a bottom plate meet as a welding line, makes an electrode weave centered on the welding line and thereby welds along the welding line. In this welding system, control is performed such that the arc voltage at a standing-plate-side weaving edge is equal to or less than the arc voltage at a welding-line center position, such that the arc voltage at a bottom-plate-side weaving edge becomes equal to or greater than the arc voltage at the welding-line center position, and such that the arc voltage at the standing-plate-side weaving edge becomes lower than the arc voltage at the bottom-plate-side weaving edge. The system can suppress occurrence of inferior bead appearance and of welding defects in horizontal fillet welding.

A welding system that, using a junction at which a standing plate and a bottom plate meet as a welding line, makes an electrode weave centered on the welding line and thereby welds along the welding line. While weaving, the electrode moves forward in a welding advancement direction until a bottom-plate-side weaving edge. When the electrode arrives at the bottom-plate-side weaving edge, the electrode moves backward with respect to the welding advancement direction until a standing-plate-side weaving edge. The electrode repeats this weaving motion on the bottom-plate side and on the standing-plate side. The system can suppress occurrence of inferior bead appearance and of welding defects in horizontal fillet welding.

A welding system that, using a junction at which a standing plate and a bottom plate meet as a welding line, makes an electrode weave centered on the welding line and thereby welds along the welding line. While weaving, the electrode moves forward in a welding advancement direction until a bottom-plate-side weaving edge. When the electrode arrives at the bottom-plate-side weaving edge, the electrode moves backward with respect to the welding advancement direction until a standing-plate-side weaving edge. The electrode repeats this weaving motion on the bottom-plate side and on the standing-plate side. The system can suppress occurrence of inferior bead appearance and of welding defects in horizontal fillet welding.

The present invention is a weld metal formed by gas shielded arc welding using a flux cored wire, the welded metal having a predetermined chemical composition, residual austenite particles being present in an amount of at least 2500 particles/mm.sup.2, and the volume fraction of residual austenite particles being at least 4.0%.