The invention discloses a method for preparing an anticorrosive surface layer of a metal material in a marine environment by laser, which belongs to the technical field of laser processing. First, the laser cladding method is used to prepare a cladding surface layer on the surface of the metal material that is not easy to undergo chemical substitution reaction with the chlorides (NaCl, MgCl.sub.2 , CaCl.sub.2 etc.) in the seawater. Then, on the surface of the cladding surface layer, ultrafast laser processing is used to form a surface layer with a wetting angle (and water) greater than 90 degrees and with hydrophobic characteristics. The anti-corrosion surface layer obtained by the invention has hydrophobic properties, the high humidity and high salt water vapor and marine organisms in the marine environment are not easy to adhere, and the anti-corrosion surface layer is stable in salt water resistance, and is not easy to undergo chemical substitution reaction with chlorides in seawater (NaCl, MgCl.sub.2 , CaCl.sub.2 etc.), which can achieve high-efficiency anti-corrosion of metal materials in the marine environment.

A device for positioning at least two joining parts during a welding process includes a support element. The support element has a surface on which for the joining parts are positioned, a recess under the joining parts when a joining region of the joining parts are on the surface, and a fluid connection for supplying a fluid to the recess. When fluid in the recess is pressurized, during a welding process to connect the joining parts a weld melt is supported by the positive pressure.

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.

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged on a first cylinder tube end, the second closure part is arranged on a second cylinder tube end to define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slides through the first closure part. The first closure part is joined to the cylinder tube by a first peripheral laser ring weld seam and the second closure part is joined to the cylinder tube by a second peripheral laser ring weld seam. The laser ring weld seams each define a fluid-tight sealing plane. A method for producing the working cylinder is provided.

A piston unit of a working cylinder includes a piston and a piston rod. The piston has an axial bore hole formed therein. The piston rod is received in the axial bore hole. The piston rod and the piston are connected by a material-bond by a circumferential laser ring weld seam. The laser ring weld seam defines a pressure medium-tight sealing plane.

A reinforcing member for cold forming according to an embodiment comprises: a blank member; and a reinforcing patch member provided to cover at least a portion of the blank member and coupled to the blank member by a plurality of welded portions, wherein the entire region of a heat-affected zone formed around the welded portions in the blank member is positioned in a region corresponding to the reinforcing patch member, and a heat-affected zone formed around a first welded portion from among the welded portions may contact the central point of a second welded portion adjacent to the first welded portion or may be formed to be spaced apart from the central point of the second welded portion.

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.

Provided are a hot-rolled steel sheet for an electric resistance welded steel pipe and a method for manufacturing the same, an electric resistance welded steel pipe and a method for manufacturing the same, a line pipe, and a building structure. The hot-rolled steel sheet has a chemical composition containing, by mass %, C: 0.030% or more and 0.20% or less, Si: 0.02% or more and 1.0% or less, Mn: 0.40% or more and 3.0% or less, P: 0.050% or less, S: 0.020% or less, N: 0.0070% or more and 0.10% or less, and Al: 0.005% or more and 0.080% or less, the balance being Fe and incidental impurities, in which N dissolved in steel is contained in an amount of 0.0010% or more and 0.090% or less, and letting a sheet thickness be t, a steel microstructure at a ½t position has an average grain size of 20.0 μm or less.

Method for joining of at least two unweldable materials, non-weldable directly to each other with thermal joining processes in a lap joint configuration, where a two step sequence is used consisting of a first step to apply a thermomechanical or mechanical surface protection layer on the surface of an unweldable material and a second step, where a thermal joining process is used to joint the sprayed layer with an applied layer sheet.

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.