A spot welded joint in which a high CTS is obtained even if including one or more high strength steel sheets and a method of welding of the same, that is, a spot welded joint 1 including a plurality of steel sheets, wherein one or more steel sheets is a tensile strength 750 to 2500 MPa high strength steel sheet and, at a cross-section in the sheet thickness direction of the steel sheets, when defining superposed surfaces of a high strength steel sheet S1 arranged at an outermost side and another steel sheet 1B as the “plane A” and defining a plane passing through a point of one-half of a distance between a nugget end position E of a high strength steel sheet S1 side on the line L1 in the sheet thickness direction and a crossing point O of the plane A and the line L1 and parallel to the plane A as the “plane B”, at a square area SA of sides of 30 μm centered about a crossing point X of a line L2, which is separated by 250 μm to the heat affected zone side from a tangent at any position on a nugget end line NEL sandwiched between the plane A and plane B and parallel to that tangent, and a line L3 vertical to L2 included in a heat affected zone 4 having a high strength steel sheet S1 as a base material, an average value of widths of the blocks formed from lath martensite is 0.5 to 7.0 μm.

A spot welded joint in which a high CTS is obtained even if including one or more high strength steel sheets and a method of welding of the same, that is, a spot welded joint 1 including a plurality of steel sheets, wherein one or more steel sheets is a tensile strength 750 to 2500 MPa high strength steel sheet and, at a cross-section in the sheet thickness direction of the steel sheets, when defining superposed surfaces of a high strength steel sheet S1 arranged at an outermost side and another steel sheet 1B as the “plane A” and defining a plane passing through a point of one-half of a distance between a nugget end position E of a high strength steel sheet S1 side on the line L1 in the sheet thickness direction and a crossing point O of the plane A and the line L1 and parallel to the plane A as the “plane B”, at a square area SA of sides of 30 μm centered about a crossing point X of a line L2, which is separated by 250 μm to the heat affected zone side from a tangent at any position on a nugget end line NEL sandwiched between the plane A and plane B and parallel to that tangent, and a line L3 vertical to L2 included in a heat affected zone 4 having a high strength steel sheet S1 as a base material, an average value of widths of the blocks formed from lath martensite is 0.5 to 7.0 μm.

A weld joint manufacturing method of the present disclosure includes performing current-passing through an aluminum-plated steel sheet provided with an aluminum plating layer while moving a pair of wheel electrodes relative to the aluminum-plated steel sheet by sandwiching the aluminum-plated steel sheet between the pair of wheel electrodes and rotating the pair of wheel electrodes in a circumferential direction; and welding a part of the aluminum-plated steel sheet, where the current-passing has been performed, and another steel sheet, in an overlapped state of the aluminum plating layer with the other steel sheet.

A weld joint manufacturing method of the present disclosure includes performing current-passing through an aluminum-plated steel sheet provided with an aluminum plating layer while moving a pair of wheel electrodes relative to the aluminum-plated steel sheet by sandwiching the aluminum-plated steel sheet between the pair of wheel electrodes and rotating the pair of wheel electrodes in a circumferential direction; and welding a part of the aluminum-plated steel sheet, where the current-passing has been performed, and another steel sheet, in an overlapped state of the aluminum plating layer with the other steel sheet.

The invention relates to a heat transfer tube (9) for falling film evaporation having a heating medium surface (21) to be heated by a heating medium, a falling film surface (20) to have spent liquor passing over it, and being made from an iron based high alloy stainless steel material with an alloy content above 16.00% for Chromium and above 1% for Nickel. The falling film surface of the heat transfer tube is equipped with one or several protrusions/indentations forming a multitude of stamped bumps (SB) on the envelope surface of a heat transfer tube such that the distance between adjacent stamped bumps (SB) along a line on the envelope surface parallel to the longitudinal axis of the heat transfer tube is within the range of 3 to 250 mm, said stamped bumps (SB) having a height (hp) in the range 0.3 to 5.0 mm, a width (wp) in the range 1.0-20 mm, and an inclination angle (a) versus a plane orthogonal to a longitudinal axis (CC) of the heat transfer tube in a range of 0-70 degrees so that each stamped bump (SB) is inclined and extends along at least a portion of the heat transfer tube or extend within a plane orthogonal to the longitudinal axis of the heat transfer tube. The invention also relates to a method for manufacturing said heat transfer tube.

The invention relates to a heat transfer tube (9) for falling film evaporation having a heating medium surface (21) to be heated by a heating medium, a falling film surface (20) to have spent liquor passing over it, and being made from an iron based high alloy stainless steel material with an alloy content above 16.00% for Chromium and above 1% for Nickel. The falling film surface of the heat transfer tube is equipped with one or several protrusions/indentations forming a multitude of stamped bumps (SB) on the envelope surface of a heat transfer tube such that the distance between adjacent stamped bumps (SB) along a line on the envelope surface parallel to the longitudinal axis of the heat transfer tube is within the range of 3 to 250 mm, said stamped bumps (SB) having a height (hp) in the range 0.3 to 5.0 mm, a width (wp) in the range 1.0-20 mm, and an inclination angle (a) versus a plane orthogonal to a longitudinal axis (CC) of the heat transfer tube in a range of 0-70 degrees so that each stamped bump (SB) is inclined and extends along at least a portion of the heat transfer tube or extend within a plane orthogonal to the longitudinal axis of the heat transfer tube. The invention also relates to a method for manufacturing said heat transfer tube.

A welding machine for welding together the tail of a billet to the head of a second billet along a feeding direction, the machine comprising a carriage adapted to slide along the feeding direction, said carriage supporting a first structure integrally fixed to said carriage; first clamping means, provided on said first structure, for clamping the head of the second billet; a second structure connected to the first structure and sliding, parallel to the feeding direction, with respect to both the first structure and the carriage; second clamping means, provided on said second structure, for clamping the tail of the first billet; wherein first adjustment means are provided for adjusting the position of the second structure with respect to the first structure along said feeding direction; and second adjustment means are provided for adjusting the position of the second structure with respect to the first structure on a plane transversal to the feeding direction, so as to align the second clamping means with the first clamping means along said feeding direction.

A welding electrode includes a weld face that has a convex base weld face surface and a plurality of ringed ridges that are radially spaced apart on the base weld face surface and surround a central weld face axis. The plurality of ringed ridges including an innermost ringed ridge and an outermost ringed ridge. The innermost ringed ridge is located closest to the central weld face axis and rises above a central portion of the base weld face surface, and the outermost ringed ridge is located farthest from the central weld face axis and rises above an outer peripheral portion of the base weld face surface. At least one of the plurality of ringed ridges is a discontinuous ringed ridge.

A welding electrode includes a weld face that has a convex base weld face surface and a plurality of ringed ridges that are radially spaced apart on the base weld face surface and surround a central weld face axis. The plurality of ringed ridges including an innermost ringed ridge and an outermost ringed ridge. The innermost ringed ridge is located closest to the central weld face axis and rises above a central portion of the base weld face surface, and the outermost ringed ridge is located farthest from the central weld face axis and rises above an outer peripheral portion of the base weld face surface. At least one of the plurality of ringed ridges is a discontinuous ringed ridge.

A method of forming an assembly includes providing a metallic first workpiece having base and a first layer disposed on the base and adhering a second layer onto the first layer. One of the first and second layers is formed of a zinc-based material formed of at least a majority of zinc, and the other of the first and second layers is formed of a metallic alloying material having a melting point higher than the melting point of the zinc-based material. Preferably, the first layer is formed of the zinc-based material, and the second layer is formed of the metallic alloying material with the higher melting point. A metallic second workpiece is disposed in contact with the second layer. A welding operation is performed to join the first workpiece to the second workpiece. A welded assembly is also provided.