CN102222547A - Preparation method of bronze Nb3Sn folded yarns with small magnetic hysteresis loss - Google Patents

Abstract

The invention relates to a preparation method of bronze Nb3Sn folded yarns with small magnetic hysteresis loss. The method is technically characterized by the following steps of: adjusting the quantity of drill holes on a primary billet and pulling to obtain a sub-group component; performing secondary assembly to obtain a final billet; and stretching and annealing to obtain folded yarns with required performance parameters. In the folded yarns obtained with a process, the Ic performance is about 240A (12T, 4.2K), the loss is about 300 mJ/cm<3> (12T, 4.2K), and the magnetic hysteresis loss of a wire rod is effectively reduced.

Description

A kind of bronze method Nb3Sn strand preparation method of low magnetic hysteresis loss

Technical field

The present invention relates to a kind of bronze method Nb3Sn strand preparation method, belong to the manufacturing technology of the bronze method low-temperature superconducting wire that international thermonuclear fusion tissue (ITER) uses in its TF coil.

Background technology

The technology of preparing of bronze method strand is the key technology of ITER with the TF conductor, according to the specification requirement of ITER, and strand critical current I _c＞190A (12T, 4.2K), magnetic hysteresis loss Q _h＜500mJ/cm ³(12T, 4.2K), our strand I of making now _c, adopt the method for designing of on the high-tin bronze billet, boring 19 holes, (12T, 4.2K), magnetic hysteresis loss is 430mJ/cm can to reach 240A ³(12T, 4.2K), though satisfied the specification requirement of ITER, loss is nearer apart from requiring, and how changing arranging of core silk on the cross-sectional area of conductor, is not reducing I _cSituation under reduce magnetic hysteresis loss effectively, and obtain a kind of high I _c, the strand of low magnetic hysteresis loss to satisfy the ITER requirement higher to strand, is the problem that needs solution.

Summary of the invention

For fear of the deficiencies in the prior art part, the present invention proposes a kind of bronze method Nb3Sn strand preparation method of low magnetic hysteresis loss.

A kind of bronze method Nb3Sn strand preparation method of low magnetic hysteresis loss is characterized in that step is as follows:

Step 1: on the high-tin bronze billet of Φ 100 * 200mm～Φ 200 * 600mm, bore 37 holes, in Φ 10～Φ 30mm niobium alloy rod patchhole, EB electron beam soldering and sealing billet is adopted at the billet cap seal dress billet two ends of adopting oxygen-free copper to make again, obtains blank to be extruded;

Step 2: under 500～600 ℃ softening temperature, billet is carried out hot extrusion, with billet by Φ 100～Φ 200mm tube reducing to Φ 30～Φ 80mm; Then adopt 10%～30% pass reduction stretching blank, the each stretching finishes once to anneal in the drawing process of the pass reduction 10%～30%, annealing temperature adopts 420 ℃～500 ℃, to Φ 8～Φ 5mm, adopt subgroup unit moulding process to obtain hexagon subgroup unit then the blank tube reducing of Φ 30～Φ 80mm;

Step 3: 0.5～2mm niobium sheet is rolled into the niobium pipe of tubulose through three roller rolling machines, adopt the machine work oxygen-free copper pipe, make the secondary billet jacket of Φ 100～Φ 200mm;

Step 4: the hexagon subgroup unit that step 3 obtains is close to inserting in the secondary billet jacket, insert the niobium pipe in the space between hexagon subgroup unit and secondary billet jacket, the billet cap seal dress billet two ends of adopting oxygen-free copper to make, adopt the soldering and sealing of EB electron beam again, obtain secondary billet to be extruded;

Step 5: under 500～600 ℃ softening temperature, billet is carried out hot extrusion, with the secondary billet by Φ 100～Φ 200mm tube reducing to Φ 30～Φ 80mm; Then adopt 10%～30% pass reduction stretching blank, the each stretching finishes once to anneal in the drawing process of the pass reduction 10%～30%, annealing temperature adopts 420 ℃～500 ℃, with the blank tube reducing of Φ 30～Φ 80mm to Φ 1.5～Φ 0.5mm, and then carry out twisting, the strand line footpath that obtains requiring by the final draw line base of 10%～20% pass reduction at last, through the chromium plating operation of 0.001～0.004 μ m thickness, obtain the Φ 0.82mmNb that the TF toroidal field coil is used ₃The Sn line.

The bronze method Nb3Sn strand preparation method of a kind of low magnetic hysteresis loss of the present invention is to change the core silk to arrange to reduce the method for magnetic hysteresis loss under the situation that does not change final conductor cores filament diameter.In the method, change arranging of core silk on the cross-sectional area of conductor, do not reducing I _cSituation under reduce magnetic hysteresis loss effectively, obtain a kind of high I _c, the strand of low magnetic hysteresis loss is to satisfy the ITER requirement higher to strand.

Description of drawings

Fig. 1: the process chart of this method;

Fig. 2: the Nb3Sn strand that 19 core methods for designing realize in the prior art;

Fig. 3: the Nb3Sn strand that 37 core methods for designing realize in this method.

Embodiment

Now in conjunction with the embodiments the present invention is further described:

Example 1:

Adopt the bronze billet of Φ 100 * 210mm, bore 37 through holes, in the high-tin bronze of afterwards the niobium rod of Φ 13mm being packed into the boring billet, and the billet cap seal dress billet two ends of adopting oxygen-free copper to make, with electron beam soldering and sealing billet, obtain treating blank one time; Through hot extrusion the billet of Φ 100 is expressed to Φ 35mm and obtains the blank that stretches, adopt the annealing process combined that stretches, the working modulus between twice annealing is 10～50%, and the bar tube reducing that makes Φ 35mm is to Φ 5mm, and it is excellent that last moulding obtains hexagonal subgroup unit.The subgroup unit and the thick niobium barrier layer of 0.5mm of boundling are assembled in the Φ 130mm oxygen-free copper jacket, soldering and sealing obtains the secondary billet, hot extrusion secondary billet again, the secondary billet of Φ 130mm is expressed to Φ 52mm, adopt billet stretching annealing process that the stretching blank of Φ 52mm is worked into Φ 1mm, after twisting, finally stretch and plating obtains TF with Φ 0.82mm Nb ₃The Sn line.Through magnetic hysteresis loss test Q _h=305mJ/cm ³(12T, 4.2K).

Example 2:

Adopt the bronze billet of Φ 160 * 400mm, bore 37 through holes, in the high-tin bronze of afterwards Φ 18mm niobium tantalum alloy rod being packed into the boring billet, and the billet cap seal dress billet two ends of adopting oxygen-free copper to make, adopt electron beam soldering and sealing billet again, obtain treating blank one time; The process hot extrusion is expressed to Φ 55mm with the billet of Φ 160, adopts the annealing process combined that stretches, and the working modulus between twice annealing is 10～50%, and the bar tube reducing that makes Φ 55mm is to Φ 7mm, and last moulding obtains the first rod of hexagonal subgroup.The subgroup unit and the thick niobium barrier layer of 1.0mm of boundling are assembled in the Φ 180mm oxygen-free copper jacket, soldering and sealing obtains the secondary billet, the process hot extrusion is extruded onto Φ 60mm with the secondary billet of Φ 180mm again, adopt billet stretching annealing process that the stretching blank of Φ 60mm is worked into Φ 1mm, after twisting, finally stretch and plating obtains TF with Φ 0.82mm Nb ₃The Sn line.Through magnetic hysteresis loss test Q _h=300mJ/cm ³(12T, 4.2K).

Example 3:

Adopt the bronze billet of Φ 185 * 550mm, bore 37 through holes, in the high-tin bronze of afterwards Φ 25mm niobium tantalum alloy rod being packed into the boring billet, and the billet cap seal dress billet two ends of adopting oxygen-free copper to make, adopt electron beam soldering and sealing billet again, obtain blank one time; The process hot extrusion is expressed to Φ 65mm with the billet of Φ 185mm, adopts the annealing process combined that stretches, and the working modulus between twice annealing is 10～50%, and the bar tube reducing that makes Φ 65mm is to Φ 8mm, and last moulding obtains the first rod of hexagonal subgroup.The subgroup unit and the thick niobium barrier layer of 1.7mm of boundling are assembled in the Φ 185mm oxygen-free copper jacket, soldering and sealing obtains the secondary billet, the process hot extrusion is extruded onto Φ 65mm with the secondary billet of Φ 185mm again, adopt billet stretching annealing process that the stretching blank of Φ 65mm is worked into Φ 1mm, after twisting, finally stretch and plating obtains TF with Φ 0.82mm Nb ₃The Sn line.Through magnetic hysteresis loss test Q _h=308mJ/cm ³(12T, 4.2K).

Claims (1)

1. the bronze method Nb3Sn strand preparation method of a low magnetic hysteresis loss is characterized in that step is as follows:

Step 1: on the high-tin bronze billet of Φ 100 * 200mm～Φ 200 * 600mm, bore 37 holes, in Φ 10～Φ 30mm niobium alloy rod patchhole, EB electron beam soldering and sealing billet is adopted at the billet cap seal dress billet two ends of adopting oxygen-free copper to make again, obtains blank to be extruded;

Step 2: under 500～600 ℃ softening temperature, billet is carried out hot extrusion, with billet by Φ 100～Φ 200mm tube reducing to Φ 30～Φ 80mm; Then adopt 10%～30% pass reduction stretching blank, the each stretching finishes once to anneal in the drawing process of the pass reduction 10%～30%, annealing temperature adopts 420 ℃～500 ℃, to Φ 8～Φ 5mm, adopt subgroup unit moulding process to obtain hexagon subgroup unit then the blank tube reducing of Φ 30～Φ 80mm;

Step 3: 0.5～2mm niobium sheet is rolled into the niobium pipe of tubulose through three roller rolling machines, adopt the machine work oxygen-free copper pipe, make the secondary billet jacket of Φ 100～Φ 200mm;

Step 4: the hexagon subgroup unit that step 3 obtains is close to inserting in the secondary billet jacket, insert the niobium pipe in the space between hexagon subgroup unit and secondary billet jacket, the billet cap seal dress billet two ends of adopting oxygen-free copper to make, adopt the soldering and sealing of EB electron beam again, obtain secondary billet to be extruded;

Step 5: under 500～600 ℃ softening temperature, billet is carried out hot extrusion, with the secondary billet by Φ 100～Φ 200mm tube reducing to Φ 30～Φ 80mm; Then adopt 10%～30% pass reduction stretching blank, the each stretching finishes once to anneal in the drawing process of the pass reduction 10%～30%, annealing temperature adopts 420 ℃～500 ℃, with the blank tube reducing of Φ 30～Φ 80mm to Φ 1.5～Φ 0.5mm, and then carry out twisting, the strand line footpath that obtains requiring by the final draw line base of 10%～20% pass reduction at last, through the chromium plating operation of 0.001～0.004 μ m thickness, obtain the Φ 0.82mmNb that the TF toroidal field coil is used ₃The Sn line.

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