Welded structure for use at very low temperatures

Claim 2

A welded structure for use at very low temperatures of below -150° C., said welded structure being a container housing a magnet of a superconducting generator rotor and having structural metallic members of austenitic stainless steel welded together with a deposited metal of austenitic stainless steel, wherein said structural metallic members have a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr and the balance substantially Fe and have a fully austenite structure; and said deposited metal has a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, not greater than 0.03 wt. % of P+S, not greater than 0.06 wt. % of oxygen, 0.005 to 0.5 wt. % of at least one of the elements selected from the group consisting of Al, Ti, Zr, Mg, Ca, Y and a rare earth element and the balance substantially Fe; said deposited metal having a fully austenite structure.

Claim 3

A welded structure for use at very low temperatures of below -150° C., said welded structure being a container housing a magnet of a superconducting generator rotor and having structural metallic members of austenitic stainless steel welded together with a deposited metal of austenitic stainless steel, wherein said structural metallic members have a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, at least one of 0.01 to 4 wt. % of Mo and 0.01 to 0.2 wt. % of N and the balance substantially Fe and have a fully austenite structure; and said deposited metal has a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, at least one of 0.01 to 4 wt. % of Mo and 0.01 to 0.2 wt. % of N, not greater than 0.03 wt. % of P+S, not greater than 0.06 wt. % of oxygen, 0.05 to 0.5 wt. % of at least one of the elements selected from the group consisting of Al, Ti, Zr, Mg, Ca, Y and a rare earth element and the balance substantially Fe and has a fully austenite structure.

Claim 4

A welded structure for use at very low temperatures of below -150° C., said welded structure being a container housing a magnet of a superconducting generator rotor and having structural metallic members of austenitic stainless steel welded together with a deposited metal of austenitic stainless steel, wherein said structural metallic members have a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, at least one of 0.01 to 4 wt. % of Mo and 0.01 to 0.2 wt. % of N and the balance substantially Fe and have a fully austenite structure; and said deposited metal has a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, at least one of 0.01 to 4 wt. % of Mo and 0.01 to 0.2 wt. % of N, not greater than 0.03 wt. % of P+S, not greater than 0.06 wt. % of oxygen, 0.05 to 0.5 wt. % of at least one of the elements selected from the group consisting of Al, Ti, Zr, Mg, Ca, Y and a rare earth element and the balance substantially Fe and has a fully austenite structure.

Claim 5

A welded structure for use at very low temperatures according to claim 1, wherein the Ni equivalent of said deposited metal, determined by the following formula, ranges between 17 and 22 wt. %: Ni equivalent=Ni(wt. %)+30×C(wt. %)+20×N(wt. %).

Claim 6

A welded structure for use at very low temperatures according to claim 2, wherein the Ni equivalent of said deposited metal, determined by the following formula, ranges between 17 and 22 wt. %: Ni equivalent=Ni(wt. %)+30×C(wt %)+20×N(wt %).

Claim 7

A welded structure for use at very low temperatures according to claim 1, wherein said container housing the magnet is comprised of an inner damper, vessel and a torque tube which are made of an austenitic stainless steel, and said magnet comprises a super-conducting magnetic field coil cooled by liquid helium which is accommodated between said vessel and said torque tube.

Claim 8

A welded structure for use at very low temperatures according to claim 2, wherein said container housing the magnet is comprised of an inner damper, vessel and a torque tube which are made of an austenitic stainless steel, and said magnet comprises a superconducting magnetic field coil cooled by liquid helium which is accommodated between said vessel and said torque tube.

Claim 9

An electric rotary machine having a superconducting rotor, wherein said superconducting rotor comprises a drive shaft having at an end thereof a flange portion, a hollow shaft confronting said drive shaft with a gap therebetween and having a flange portion, a torque tube connected between said flange portions, a magnetic field coil provided on an outer peripheral surface of said torque tube, a vessel surrounding said magnetic field coil, a coolant pool formed inside said torque tube, collant supply means for supplying a coolant to said coolant pool through said hollow shaft, a cylindrical inner damper provided so as to surround said vessel, a cylindrical outer damper disposed so as to surround said inner damper and connected between said flange portions, coolant discharge means for collecting said coolant from said coolant pool through said hollow shaft, and a power lead passing through said hollow shaft for supplying said magnetic field coil with electric power, and wherein said torque tube, said vessel and said inner damper are made of an austenitic stainless steel having a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr and the balance substantially Fe and having a fully austenite structure; and said torque tube and said vessel and said torque tube and said inner damper are, respectively, welded together with a deposited metal of austenitic stainless steel having a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, not greater than 0.03 wt. % of P+S, not greater than 0.06 wt. % of oxygen, 0.005 to 0.5 wt. % of at least one of the elements selected from the group consisting of Al, Ti, Zr, Mg, Ca, Y and a rare earth element and the balance substantially Fe; said deposited metal having a fully austenite structure.

Claim 10

An electric rotary machine having a superconducting rotor, wherein said superconducting rotor comprises a drive shaft having at an end thereof a flange portion, a hollow shaft confronting said drive shaft with a gap therebetween and having a flange portion, a torque tube connected between said flange portions, a magnetic field coil provided on an outer peripheral surface of said torque tube, a vessel surrounding said magnetic field coil, a coolant pool formed inside said torque tube, collant supply means for supplying a coolant to said coolant pool through said hollow shaft, a cylindrical inner damper provided so as to surround said vessel, a cylindrical outer damper disposed so as to surround said inner damper and connected between said flange portions, coolant discharge means for collecting said coolant from said coolant pool through said hollow shaft, and a power lead passing through said hollow shaft for supplying said magnetic field coil with electric power, and wherein said torque tube, said vessel and said inner damper are made of an austenitic stainless steel having a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr and the balance substantially Fe and having a fully austenite structure; and said torque tube and said vessel and said torque tube and said inner damper are, respectively, welded together with a deposited metal of austenitic stainless steel having a chemical composition consisting essentially of 0.01 to 0.1 wt. % of C, 0.05 to 1 wt. % of Si, 1 to 10 wt. % of Mn, 8 to 20 wt. % of Ni, 16 to 22 wt. % of Cr, not greater than 0.03 wt. % of P+S, not greater than 0.06 wt. % of oxygen, 0.005 to 0.5 wt. % of at least one of the elements selected from the group consisting of Al, Ti, Zr, Mg, Ca, Y and a rare earth element and the balance substantially Fe; said deposited metal having a fully austenite structure.