To provide a method and apparatus for manufacturing a joined member that inhibit occurrence of cracks in a joined member even when the joined portion is quenched when members are welded together. The method includes placing the first member D and the second member E with a joint target portion Df and a joint target portion Ef being in contact with each other, welding the joint target portions by heating, subjecting the first member D after the welding to a process for inhibiting occurrence of cracks, and tempering a portion where the first and second members have been welded to each other by electromagnetic heating. The apparatus includes a first electrode 11 to contact with the first member D; a second electrode 12 to contact with the second member E; and an induction heating coil 23 for performing induction heating of a portion where a joint target portions Df and Ef have been contacted and joined to each other, and the induction heating coil 23 is placed between the two electrodes 11 and 12 when the induction heating is performed.

Provided is a clad welded pipe or tube that has improved pipe or tube mechanical properties by reducing the width of a weld without its function as a clad pipe or tube being impaired. A clad welded pipe or tube comprises: a first layer made of base metal; and a second layer placed on one surface of the first layer, and made of first cladding metal that is a material different from the base metal, wherein a pipe or tube circumferential length L1 of weld metal at a pipe or tube inner surface and a pipe or tube circumferential length L2 of the weld metal at a pipe or tube outer surface in a weld are each 0.0010 mm or more and 1.0 mm or less, and the base metal is not exposed at a first cladding metal-side surface of the clad welded pipe or tube in the weld.

To provide a fitting member, an annular member, a joined member and a method of manufacturing the joined member, which prevent occurrence of a not-joined portion. A fitting member 10 has a fitting protrusion 10p which is protruded outward on an outside face 10s. An annular member 20 contains a space 20h in which the fitting member 10 is to be fitted. An annular member 20 has an annular protrusion 20p on an inside face 20f. When the fitting member 10 is fitted into the space 20h at a predetermined depth, the fitting protrusion 10p and the annular protrusion 20p fill not-joined portions which may be generated assuming that they are not provided. A joined member 30 is produced by fitting the fitting member 10 into the space 20h at the predetermined depth, so that a contact portion between the fitting member 10 and the annular member 20 is joined in solid phase.

Provided is a method of resistance spot welding that can inhibit breakage of a high-tensile steel plate without materials being limited. One aspect of the present disclosure is a method of resistance spot welding including welding of a workpiece made of layered steel plates with a resistance spot welding apparatus. The resistance spot welding apparatus includes a first electrode contacting a first steel plate that is a high-tensile steel plate among the steel plates, and a second electrode contacting a second steel plate having less tensile strength than the first steel plate among the steel plates and configured such that the workpiece is interposed between the first electrode and the second electrode. In the welding, the first steel plate is compressed in a direction that intersects a thickness direction of the first steel plate at least from during welding of the workpiece until completion of welding of the workpiece.

A resistance welding apparatus can employ a modular power supply system with multiple power supply modules and leads for electrically connecting the modular power supply system to a welding resistor. The resistance welding apparatus is selectively configurable in at least three of (i) a first configuration in which the leads connect the first power supply module to the resistor and the second power supply module is disconnected from the resistor; (ii) a second configuration in which the leads connect the second power supply module to the resistor and the first power supply module is disconnected from the resistor; (iii) a third configuration in which the leads connect the first and second power supply modules to the resistor in series; and (iv) a fourth configuration in which the leads connect the first and second power supply modules to the resistor in parallel.

A resistance welding apparatus can employ a modular power supply system with multiple power supply modules and leads for electrically connecting the modular power supply system to a welding resistor. The resistance welding apparatus is selectively configurable in at least three of (i) a first configuration in which the leads connect the first power supply module to the resistor and the second power supply module is disconnected from the resistor; (ii) a second configuration in which the leads connect the second power supply module to the resistor and the first power supply module is disconnected from the resistor; (iii) a third configuration in which the leads connect the first and second power supply modules to the resistor in series; and (iv) a fourth configuration in which the leads connect the first and second power supply modules to the resistor in parallel.

A resistance spot welding method is disclosed for joining two or more steel sheets including at least one steel sheet having a tensile strength of 980 MPa or higher. The resistance spot welding method involves placing the steel sheets on top of each other to form a set of steel sheets to be welded, clamping the set of steel sheets with a pair of electrodes, and passing a current through the steel sheets while applying pressure thereto to join the steel sheets together. The resistance spot welding method includes an initial welding step of welding by passing a current I1 (kA) satisfying 2×√F1<I1≤10×√F1 while applying a welding force F1 (kN) satisfying 0.2×√t1<F1≤4×√t1, and a main welding step of forming a nugget having a predetermined nugget diameter. Spatter is produced in the initial welding step.

A resistance spot welding method is disclosed for joining two or more steel sheets including at least one steel sheet having a tensile strength of 980 MPa or higher. The resistance spot welding method involves placing the steel sheets on top of each other to form a set of steel sheets to be welded, clamping the set of steel sheets with a pair of electrodes, and passing a current through the steel sheets while applying pressure thereto to join the steel sheets together. The resistance spot welding method includes an initial welding step of welding by passing a current I1 (kA) satisfying 2×√F1<I1≤10×√F1 while applying a welding force F1 (kN) satisfying 0.2×√t1<F1≤4×√t1, and a main welding step of forming a nugget having a predetermined nugget diameter. Spatter is produced in the initial welding step.

The present invention relates to an air conditioner. The air conditioner according to the present embodiment has a refrigeration capacity of 7 kW to 11 kW, inclusive, and uses a refrigerant R32 as a refrigerant, and since a refrigerant pipe therein is made of a ductile stainless steel material having 1% or less of a delta-ferrite matrix structure with respect to the grain size area thereof, and includes a suction pipe guiding the suction of the refrigerant into a compressor and having an outer diameter of 15.88 mm, the refrigerant pipe can maintain strength and hardness as good as or better than those of a copper pipe, while also maintaining good processability.

This disclosure relates to weldability of steel alloys that provide weld joints which retain hardness values in a heat affected zone adjacent to a fusion zone and which also have improved resistance to liquid metal embrittlement due to the presence of zinc coatings.