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.

The present invention relates to an air conditioner. The air conditioner according to the present embodiment has a refrigeration capacity of 11 kW to 16 kW, inclusive, and uses R32 as a refrigerant circulating therein, 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, the refrigerant pipe can maintain strength and hardness as good as or better than those of a copper pipe, while also maintaining good processability.

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, as a refrigerant, a mixed refrigerant containing 50% or more of R32, 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.

The present invention relates to steel pipe excellent in toughness of the weld metal part at a low temperature obtained by submerged arc welding in the longitudinal direction from both the inside and outside surfaces having strengths of the X60 to X70 class. The steel pipe of the present invention is a pipe having weld zones welded in a longitudinal direction at an inside surface and outside surface, wherein the tensile strength of the base metal is 480 to 620 MPa, the weld metal has a predetermined composition of constituents, when % X expresses a content of an element X in the weld metal, Pcm defined by Pcm=% C+% Si/30+(% Mn+% Cu+% Cr)/20+% Ni/60+% Mo/15+% V/10+5% B is 0.2% or less, Ceq defined by Ceq=% C+% Mn/6+(% Cr+% Mo+% V)/5+(% Ni+% Cu)/15 is 0.35 to 0.45%, and defined by =(1.5(% O-0.89% Al)+3.4% N-% Ti)1000 is 20 to 40, and % Al/% O is 0.3 to 0.8.

A preferable aspect of the present invention provides: an ultra-high-strength hot-rolled steel sheet containing, by weight, one or two of 0.40-0.60% of C, 0.7-1.5% of Mn, 0.3% or less (excluding 0%) of Si, 0.03% or less (including 0%) of P, 0.004% or less (including 0%) of S, 0.04% or less (excluding 0%) of Al, 0.3% or less (excluding 0%) of Cr, 0.3% or less (excluding 0%) of Mo, 0.9-1.5% of Ni, and 0.9-1.5% of Cu, 1.1% or more of Cu+Ni, 0.04% or less (excluding 0%) of Ti, 0.005% or less (excluding 0%) of B, 0.006% or less (excluding 0%) of N, and the balance Fe and other impurities, the alloy elements satisfying relational formulas 1 and 2 below, wherein a microstructure of the hot-rolled steel sheet comprises, by volume, 7% or more of ferrite and 93% or less of perlite; a steel pipe and a member each using the same; and manufacturing methods therefor. [Relational formula 1] (Mn/Si) #3 (weight ratio) [Relational formula 2] (Ni/Si) #1 (weight ratio)

A carrier component for a vehicle application, formed by two half-shells that are welded to one another at contact sides. When assembling the two half-shells for joining same at the contact sides, in a position in which the two half-shells are arranged above one another, the point of contact of the lower half-shell protrudes in relation to the external closed side of the other half-shell. The point of contact of one of the two half-shells protrudes inward in relation to the internal closed side of the other half-shell. A method for producing a carrier component from two half-shells is also disclosed.

For producing a welded ring, a band of a length corresponding to the circumference of the ring is bent into a ring and its two ends are welded together. The band ends to be welded together have an offset in the circumferential direction of the ring, the offset lying in the plane of the band. The welding is performed from both lateral edges of the ring, from the outside to the inside up to the offset. Welding having an overall improved welding quality and a higher tensile strength is thus obtained.

The present disclosure relates to electro-conduction devices and methods for submerged arc welding of straight-seam steel pipes and in particular to a lateral electro-conduction device and method for multi-wire submerged arc inner/outer welding of a straight-seam steel pipe. The present disclosure aims to overcome the problem of poor closing of the electromagnetic field resulting from the existing negative-pole electro-conduction mechanism and the problem of unstable welding process resulting from bending deformation in the steel pipe welding process. The device includes: a floating surface contact electro-conduction device, capable of forming a surface contact with an outer surface of the straight-seam steel pipe; a lateral electro-conduction brush device, including multiple electro-conduction brushes and electrically connected with the floating surface contact electro-conduction device; a lateral electro-conduction metal plate, electrically connected with a negative-pole wire harness of a welding machine and electrically connected with the lateral electro-conduction brush device. Therefore, an electro-conduction circuit is formed by the negative-pole wire harness, the lateral electro-conduction metal plate, the lateral electro-conduction brush device, the floating surface contact electro-conduction device, the straight-seam steel pipe and a welding wire electrode.

A position detection device for a seam portion and a heated portion of a welded steel pipe detects a position of the seam portion of the welded steel pipe and a position of the heated portion generated by heating the seam portion and/or near the seam portion, and includes: an irradiation unit configured to emit light; an imaging device configured to capture a first image of the seam portion and the heated portion irradiated with light and a second image of the seam portion and the heated portion not irradiated with light; and a control device configured to control light irradiation by the irradiation unit and an imaging timing of the imaging device.

A method for producing a steel material for line pipes including heating a steel having a specific composition to a temperature of 1000? C. to 1200? C.; performing hot rolling such that a cumulative rolling reduction ratio in a non-recrystallization temperature range is 60% or more, a cumulative rolling reduction ratio in a temperature range of (a rolling finish temperature +20? C.) or less is 50% or more, and a rolling finish temperature is the Ar.sub.3 transformation point or more and 790? C. or less; subsequently performing accelerated cooling from a temperature of the Ar.sub.3 transformation point or more, at a cooling rate of 10? C./s or more, to a cooling stop temperature of 200? C. to 450? C.; and then performing reheating such that the temperature of a surface of the steel plate is 350? C. to 550? C. and the temperature of the center of the steel plate is less than 550? C.