The disclosed technology generally relates to consumable electrode wires and more particularly to consumable electrode wires having a core-shell structure, where the core comprises aluminum. In one aspect, a welding wire comprises a sheath having a steel composition and a core surrounded by the sheath. The core comprises aluminum (Al) at a concentration between about 3 weight % and about 20 weight % on the basis of the total weight of the welding wire, where Al is in an elemental form or is alloyed with a different metal element. The disclosed technology also relates to welding methods and systems adapted for using the aluminum-comprising electrode wires.

A flux-cored wire of the present disclosure has a steel sheath and a flux filled at an inside of the steel sheath, has a total amount of moisture by ratio with respect to a total wire mass of 300 ppm or less, has flux containing fluorides, and has an amount of the fluorides by ratio with respect to the total wire mass of, by total of values converted to F, 0.11 mass % or more and 2.50 mass % or less. If using the flux-cored wire of the present disclosure for welding, a stable weld shape can be obtained and, further, the amount of diffusible hydrogen of the weld metal can be reduced. For this reason, the flux-cored wire of the present disclosure can be suitably used for welding high strength steel such as ferrite steel.

A junction structure includes a first metallic material, a second material different in type from the first metallic material, and a welding wire as a third material similar to the first metallic material. The second material is stacked on the first material. The molten metal of the third metallic material is deposited by arc welding into the through part of the second material so as to form a flanged or tapered bead, so that the first and third metallic materials and the second material are fixed together.

A junction structure includes a first metallic material, a second material different in type from the first metallic material, and a welding wire as a third material similar to the first metallic material. The second material is stacked on the first material. The molten metal of the third metallic material is deposited by arc welding into the through part of the second material so as to form a flanged or tapered bead, so that the first and third metallic materials and the second material are fixed together.

A method for welding a welded part to a component is carried out as arc ignition welding by use of direct current, having a bias current phase in which an arc is formed between the negatively polarized welded part and the component, and a subsequent main current phase for melting material to the joint. The welded part: a) is a galvanized sphere made of C10C having a roundness G500, wherein the size of any zinc inclusions under the surface of the sphere equals 10 micrometers at maximum, orb) is formed by welding a galvanized sphere made of C10C having a roundness G500, wherein the size of any zinc inclusions under the surface of the sphere equals 10 micrometers at maximum, to a connection element.

A method for welding a welded part to a component is carried out as arc ignition welding by use of direct current, having a bias current phase in which an arc is formed between the negatively polarized welded part and the component, and a subsequent main current phase for melting material to the joint. The welded part: a) is a galvanized sphere made of C10C having a roundness G500, wherein the size of any zinc inclusions under the surface of the sphere equals 10 micrometers at maximum, orb) is formed by welding a galvanized sphere made of C10C having a roundness G500, wherein the size of any zinc inclusions under the surface of the sphere equals 10 micrometers at maximum, to a connection element.

A welded joint comprising: a pair of steel base materials having a sheet thickness of 0.4 to 4.0 mm, and at least one of which has a tensile strength of 780 MPa or more; and a weld metal that welds the pair of steel base materials, wherein, when the weld metal is seen in plan view, a weld toe of the weld metal has peaks and valleys, an average distance in a direction orthogonal to a weld line direction between a top point of a peak and a bottom point of a valley that are adjacent to one another is 3.0 mm or less, and an average number of a total of peaks and valleys, at which the distance in the direction orthogonal to the weld line direction between the top point of the peak and the bottom point of the valley that are adjacent to one another is 0.1 mm to 3.0 mm, is 2 to 30/15 mm, and an automobile component having the welded joint.

A welded joint comprising: a pair of steel base materials having a sheet thickness of 0.4 to 4.0 mm, and at least one of which has a tensile strength of 780 MPa or more; and a weld metal that welds the pair of steel base materials, wherein, when the weld metal is seen in plan view, a weld toe of the weld metal has peaks and valleys, an average distance in a direction orthogonal to a weld line direction between a top point of a peak and a bottom point of a valley that are adjacent to one another is 3.0 mm or less, and an average number of a total of peaks and valleys, at which the distance in the direction orthogonal to the weld line direction between the top point of the peak and the bottom point of the valley that are adjacent to one another is 0.1 mm to 3.0 mm, is 2 to 30/15 mm, and an automobile component having the welded joint.

A double-wall spiral welded pipe includes a first steel belt layer and a second steel belt layer which have equal widths, are arranged in parallel and align with each other; at least two supporting steel bars perpendicular to the first steel belt layer and the second steel belt layer are arranged between the first steel belt layer and the second steel belt layer; the supporting steel bars are arranged on end parts of two sides of the first steel belt layer and the second steel belt layer and extend together with the first steel belt layer and the second steel belt layer; and the first steel belt layer, the second steel belt layer and the supporting steel bars on the end parts of the two sides are mutually welded to form a double-layer composite steel belt with a rectangular section in an extending direction.

A lap fillet arc welded joint includes: a first steel sheet and a second steel sheet which are overlapped each other, the first steel sheet and the second steel sheet each having a tensile strength of 950 MPa or more; and a weld metal which extends along a corner formed by an upper surface of the first steel sheet and an end surface of the second steel sheet. When: a toe angle of the weld metal is defined as β; the total number of concave portions present on the surface of the weld metal included a range of 0.4 mm or less from a fusion boundary is defined as NA; and the number of concave portions in contact with ferrite grains having a maximum grain size of 10 μm or more is defined as NB, the weld metal satisfies the following conditional expressions (1) and (2) at the same time.
0°<β<30°  (1)
NB/NA≤0.70  (2)
(Here, NA is 20 or more).