Provided is an austenitic stainless steel weld joint that is excellent in polythionic acid SCC resistance and naphthenic acid corrosion resistance, and is also excellent in creep ductility. An austenitic stainless steel weld joint includes a base material and a weld metal. The weld metal has a chemical composition at its width-center position and at its thickness-center position consisting of, in mass %, C: 0.050% or less, Si: 0.01 to 1.00%, Mn: 0.01 to 3.00%, P: 0.030% or less, S: 0.015% or less, Cr: 15.0 to 25.0%, Ni: 20.0 to 70.0%, Mo: 1.30 to 10.00%, Nb: 0.05 to 3.00%, N: 0.150% or less, and B: 0.0050% or less, with the balance: Fe and impurities.

A process for room temperature substrate bonding employs a first substrate substantially transparent to a laser wavelength is selected. A second substrate for mating at an interface with the first substrate is then selected. A transmissivity change at the interface is created and the first and second substrates are mated at the interface. The first substrate is then irradiated with a laser of the transparency wavelength substantially focused at the interface and a localized high temperature at the interface from energy supplied by the laser is created. The first and second substrates immediately adjacent the interface are softened with diffusion across the interface to fuse the substrates.

Provided is a resistance spot welding method wherein main current passage includes two or more electrode force application steps including a first electrode force application step and a second electrode force application step following the first electrode force application step, an electrode force F.sub.1 in the first electrode force application step and an electrode force F.sub.2 in the second electrode force application step in the main current passage satisfy a relationship F.sub.1<F.sub.2, and an electrode force switching point T.sub.f from the first electrode force application step to the second electrode force application step in the main current passage is set to satisfy predetermined relational formulas.

A cap tip assembly for spot welding is disclosed. The cap tip assembly for spot welding is configured to spot-weld a first base material in which a flange is formed and a second base material overlapping the flange in a vertical direction. The cap tip assembly for spot welding includes a tip body provided in a shape of a rectangular block in which a round-shaped welding section is formed on a front side of a top surface, and a collet member coupled to the tip body to guide a conductive tape to the welding section.

A laser welding method is a method for joining a first member in the shape of a plate and made of a metal material to a second member made of a metal material by laser welding. The laser welding method includes an arranging step and a laser beam irradiation step. In the arranging step, the second member is brought into contact with or brought close to one main surface of the first member. In the laser beam irradiation step, the other main surface of the first member is irradiated with the laser beam, the other surface being a main surface opposite to the one main surface of the first member. In the laser beam irradiation step, the first member and the second member are melted to form a weld portion having a substantially circular or oval shape in a plan view and to form a fillet on a joined portion between the first member and the second member.

Art for spot welding able to suppress penetration of hydrogen, one of the factors behind delayed fracture, at the time of spot welding, that is, a spot welding method in which at one or both of the surfaces of the steel sheets becoming the facing surfaces of the overlaid steel sheets, a location where the steel sheets contact each other to form a contact part at the time of initial squeezing of the spot welding is worked in advance to form a plurality of lines running through the contact part and connected to the outside of the contact part and the spot welding is performed at the location of the contact part and also a steel sheet in which the plurality of lines are formed in advance at the location becoming a contact part when steel sheets contact each other at the time of initial squeezing in the spot welding.

Disclosed is a clad steel plate with further improved low temperature toughness along with excellent HIC resistance while ensuring a tensile strength of 535 MPa or more. A clad steel plate includes: a base steel; and a clad metal made of a corrosion resistant alloy bonded to one surface of the base steel, in which the base steel has: a chemical composition with appropriately controlled values of ACR and P.sub.HIC; and a steel microstructure in which bainite is present in an area fraction of 94% or more at a ½ thickness position in a thickness direction of the base steel, and with an average crystal grain size of 25 μm or less, and shear strength at a bonded interface between the base steel and the cladding metal is 300 MPa or more.

A laser welding method is provided to ensure a sufficient joining strength between metal plates by increasing the area of a joining region while preventing “burn through” of a molten metal. In the laser welding method by applying a laser beam to a surface of multiple metal plates superimposed on each other, a scanning locus with the laser beam is sequentially shifted from an inner circular scanning locus to an outer one in a predetermined joining region on the metal plates, and an emission interval is provided to temporally stop the metal-plate-surface irradiation when the scanning locus is shifted. Thus, every time the scanning locus is shifted, the molten metal due to the previous irradiation is cooled and increases its viscosity. Accordingly, the “burn through” is prevented regardless of increase of the area of the joining region, which results in a sufficient joining strength between the metal plates.

A hot formed joined blank includes a first metal blank having an ultimate tensile strength of ≥about 1300 MPa to ≤about 2000 MPa and defining a first surface, a second metal blank having an ultimate tensile strength of ≥about 400 MPa to ≤about 1200 MPa and defining a second coated surface having a coating disposed thereon. The coating includes aluminum and silicon or in alternative variations, zinc. A third surface of the second metal blank is joined to the first surface of the first metal blank to form the hot formed joined blank. A weld nugget is disposed along a boundary between the first and second metal blanks that is configured to join the first and second metal blanks, where the weld nugget optionally includes less than or equal to about 1.5 weight percent aluminum or a microstructure comprising austenite and delta-ferrite.

A manufacturing method for a joint body having a first metal member and a second metal member joined together by causing a laser oscillation system to irradiate a surface of the second metal member placed on the first metal member with laser light to form a joint portion including a welded portion where the first metal member and the second metal member are joined together includes continuously supplying the second metal member while pressing the second metal member against the first metal member, the second metal member being a hoop material, and causing the laser oscillation system to emit the laser light.