The present invention relates to an air conditioner. A first invention according to the present embodiment is an air conditioner which has a refrigeration capacity of 16 kW to 28 kW, inclusive, and uses a mixed refrigerant R134a as a refrigerant, and in which a refrigerant pipe includes a ductile stainless steel pipe having 1% or less of a delta-ferrite matrix structure with respect to the grain size area thereof.

Described is a hot-rolled steel strip product including a composition consisting of, in terms of weight percentages, 0.14% to 0.35% C, 0% to 0.5% Si, 0.05% to 0.40% Mn, 0.1% or less Al, 0.1% to 0.4% Cu, 0.2% to 0.9% Ni, 0.2% to 0.9% Cr, 0.2% or less Mo, 0.005% or less Nb, 0.035% or less Ti, 0.05% or less V, 0.0005% to 0.0050% B, 0.025% or less P, 0.008% or less S, 0.01% or less N, 0.01% or less Ca, and the remainder being Fe and inevitable impurities, wherein the steel product has a Brinell hardness in the range of 420 to 580 HBW.

A method for manufacturing a shaped article includes a step of providing a high-speed steel powder, a step of forming a powder layer by spreading the powder, a step of forming a solidified layer in which the powder is in a bound state by irradiating the powder layer with a scanning laser beam, and a step of stacking up solidified layers by sequentially repeating the step of forming a powder layer and the step of forming a solidified layer, thereby forming the shaped article. The laser beam has an energy density of 60 J/mm.sup.3 or more and less than 600 J/mm.sup.3.

A method for manufacturing a shaped article includes a step of providing a high-speed steel powder, a step of forming a powder layer by spreading the powder, a step of forming a solidified layer in which the powder is in a bound state by irradiating the powder layer with a scanning laser beam, and a step of stacking up solidified layers by sequentially repeating the step of forming a powder layer and the step of forming a solidified layer, thereby forming the shaped article. The laser beam has an energy density of 60 J/mm.sup.3 or more and less than 600 J/mm.sup.3.

A manufacturing method for a three-dimensional molded object includes repeating formation of a material layer and formation of a solidified layer, the material layer being formed by spreading a metal material on a base plate and the solidified layer being formed by irradiating the material layer with a laser beam or an electron beam, thereby molding a solidified body which is a laminated solidified layer on the base plate; and subjecting the base plate and the solidified body after molding to a heat treatment.

A manufacturing method for a three-dimensional molded object includes repeating formation of a material layer and formation of a solidified layer, the material layer being formed by spreading a metal material on a base plate and the solidified layer being formed by irradiating the material layer with a laser beam or an electron beam, thereby molding a solidified body which is a laminated solidified layer on the base plate; and subjecting the base plate and the solidified body after molding to a heat treatment.

A cold rolled and annealed steel sheet including by weight: 0.6<C<1.3%, 15≤Mn<35%, 6≤Al<15%, Si≤2.40%, S≤0.03%, P≤0.1%, N≤0.1%, possibly one or more optional elements chosen among Ni, Cr and Cu in an individual amount of up to 3% and possibly one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, the remainder of the composition making up of iron and inevitable impurities resulting from the elaboration, the microstructure of the sheet including of ordered ferrite between 1% and 10%, optionally of up to 10% of kappa carbides, the remainder being made of austenite, and, the density of the steel sheet being equal or below 7.2 and the FWHM for the austenite matrix is between 0.700 and 1.100.

A method quenches a steel pipe and an apparatus quenches a steel pipe by which a steel pipe having excellent and uniform quality can be acquired by applying uniform rapid cooling to the steel pipe in a longitudinal direction as well as in a circumferential direction of the steel pipe using a simple unit. Movements of a heated steel pipe in a direction parallel to and in a direction perpendicular to a pipe axis of the steel pipe are stopped, and cooling water is jetted onto an outer surface of the steel pipe from four or more spray nozzles arranged spirally outside the steel pipe while rotating the steel pipe about the pipe axis.

A method quenches a steel pipe and an apparatus quenches a steel pipe by which a steel pipe having excellent and uniform quality can be acquired by applying uniform rapid cooling to the steel pipe in a longitudinal direction as well as in a circumferential direction of the steel pipe using a simple unit. Movements of a heated steel pipe in a direction parallel to and in a direction perpendicular to a pipe axis of the steel pipe are stopped, and cooling water is jetted onto an outer surface of the steel pipe from four or more spray nozzles arranged spirally outside the steel pipe while rotating the steel pipe about the pipe axis.

A heat-treatment apparatus includes a casing, a loader which loads a workpiece to an inner part of the casing in order to apply a heat-treatment to the workpiece, and a canopy surface provided in the casing to cover the workpiece. The canopy surface includes a slope way with a sectional configuration where the canopy surface is cut on a plane vertical to a conveying direction of the workpiece inside the casing. The slope way includes a highest point and a downward inclined surface extending from the highest point to an outside of a zone between a perpendicular line extending from a left end of the workpiece and a perpendicular line extending from a right end of the workpiece.