Production method of large-diameter high-strength oxygen-free silver-copper rod for nuclear power unit

Abstract

The invention relates to the technical field of nonferrous metal material processing, and discloses a method for producing a large-diameter high-strength oxygen-free silver-copper rod for a nuclear power unit, which is suitable for manufacturing a TUAg0.1 oxygen-free silver-copper rod with the diameter phi of 70-85 mm. The method comprises the following steps: casting a solid circular cast ingot with the diameter phi of 360 mm and sawing; the cast ingot is heated to 740-780 DEG C; extruding into an extruded bar blank with the length of 3-5m; straightening the extruded bar blank until the straightness is less than or equal to 3mm / m; machining and manufacturing a stretching chuck; 4-pass continuous drawing machining is carried out, and the diameter reducing amount of each pass is 5-10 mm; and finally, straightening, sawing, sizing and other finishing operations are carried out. The manufacturing problem of a large-diameter bar billet stretching chuck is solved, a high-performance product with Rm larger than or equal to 270 MPa and A larger than or equal to 8% is obtained through the multi-pass stretching and work hardening principle, the strict requirement for a nuclear power unit conductive screw is met, and industrial production is easy.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal material processing, and in particular to a method for producing a large-diameter high-strength oxygen-free silver-copper rod for a nuclear power unit. Background Art

[0002] With the vigorous development of my country's nuclear power industry, nuclear power, as a clean and efficient energy form, is gradually becoming an important part of the country's energy structure. In order to meet the growing energy demand, multiple nuclear power units are being put into construction and operation in full swing. These nuclear power units not only require materials to have extremely high reliability and safety, but also put forward more stringent requirements on the performance of materials.

[0003] In the manufacturing process of nuclear power units, large-diameter, high-strength oxygen-free silver copper rods for conductive screws are a crucial material. The copper rods must have a grade of TUAg0.1, a diameter range of φ70mm to φ85mm, and extremely high mechanical properties, which must reach Rm (tensile strength) ≥270MPa, A (elongation) ≥8%. These performance indicators far exceed those of ordinary materials, making their production extremely difficult.

[0004] At present, there is no existing production process on the market that can meet the stringent requirements of large-diameter, high-strength, oxygen-free silver-copper rods for conductive screws. Although the traditional copper rod production process can meet the production needs of ordinary copper rods to a certain extent, it often seems to be unable to meet such high performance requirements. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a production method for large-diameter high-strength oxygen-free silver-copper rods for nuclear power units. The difficulty in manufacturing large-diameter rod blank stretching chucks is solved by straightening first and then turning. A four-pass continuous stretching process is adopted, combined with the principle of work hardening, to finally obtain high-quality products with Rm≥270MPa and A≥8%, which meet and exceed the performance requirements of conductive screws of nuclear power units and are easy to industrialize.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme, a method for producing a large-diameter high-strength oxygen-free silver-copper rod for a nuclear power unit, wherein the diameter of the oxygen-free silver-copper rod is φ70 mm to φ85 mm, characterized in that the method comprises the following steps:

[0007] Cast oxygen-free silver-copper alloy solid round ingots, ingot diameter φ360mm, sawn into single ingots with a length of 500mm-550mm;

[0008] Heat the sawn ingot to 740-780°C;

[0009] The heated ingot is extruded to obtain an extruded rod blank with a length of 3-5 meters;

[0010] Straighten the extruded rods to a straightness of ≤3mm / m;

[0011] The stretching chuck is made by machining one end of the straightened extruded rod blank. The shape of the stretching chuck includes: a chuck cylindrical section with a length of 150mm; a shoulder conical section with a length of 100-120mm;

[0012] The extruded rod is subjected to continuous multi-pass stretching processing, the number of passes is 4, and the diameter reduction of each pass matches the stretching capacity of the stretching equipment and the plasticity of the material;

[0013] The finished bars are straightened, sawed to length and finished to obtain large-diameter high-strength oxygen-free silver-copper bars of φ70-φ85mm for nuclear power units that meet the requirements.

[0014] As a production method for large-diameter high-strength oxygen-free silver-copper rods of a nuclear power unit of the present invention, further, the diameter of the extruded rod blank obtained after the extrusion is φ95-φ110 mm.

[0015] As a production method for large-diameter high-strength oxygen-free silver-copper rods of nuclear power units of the present invention, further, in the continuous multi-pass stretching process, the diameter reduction of each pass is 5-10 mm.

[0016] Beneficial effects of the present invention:

[0017] The invention successfully solves the manufacturing problem of a stretching chuck for a large-diameter bar blank with a diameter of 95-110 mm, and effectively overcomes the limitation of the traditional method by straightening first and then turning the stretching chuck with a lathe; a continuous 4-pass stretching process is adopted, and the diameter reduction in each pass is accurately controlled to be 5-10 mm, which matches the capacity of the stretching equipment and the plasticity of the material, ensures the smooth deformation of the bar, and significantly improves the strength of the oxygen-free silver-copper rod by utilizing the work hardening principle; the φ70-φ85 mm TUAg0.1 oxygen-free silver-copper rod finally produced has excellent mechanical properties, Rm≥270 MPa, A≥8%, which fully meets the high standard requirements for conductive screws of nuclear power units, and the Rm of the product in the embodiment reaches 322-325 MPa, and A reaches 16%, which far exceeds the design requirements; in addition, the process flow of the invention is clear and concise, easy to operate and control, and very suitable for industrial large-scale production. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention is further described below in conjunction with specific embodiments.

[0019] Embodiment 1:

[0020] Comparison of mechanical properties requirements between ordinary pure copper drawn rods (implementing GB / T4423-2020 "Copper and Copper Alloy Drawn Rods") and large-diameter high-strength oxygen-free silver-copper rods for conductive screws:

[0021] The production process of high-strength oxygen-free silver copper rods for TUAg0.1, φ85mm conductive screws is as follows:

[0022] S1. Cast TUAg0.1 solid round ingot with ingot diameter of φ360mm and saw into single ingot length of 500mm-550mm;

[0023] S2, heating the ingot to 740-780°C;

[0024] S3, extruding the ingot to obtain a φ105mm extruded rod blank with a length of 3-5 meters;

[0025] S4. Straighten the φ105mm extruded rod blank to a straightness of ≤3mm / meter;

[0026] S5. Making a stretching chuck at one end of a φ105mm extruded rod;

[0027] S6. The φ105mm extruded rod blank is subjected to multiple stretching processes on a 50-ton chain stretching machine to obtain a finished rod with a diameter of φ85mm;

[0028] 1st pass: φ105mm stretched to φ100mm,

[0029] Second pass: φ100mm stretched to φ95mm,

[0030] The third pass: φ95mm stretched to φ90mm,

[0031] The 4th pass: φ90mm stretched to φ85mm,

[0032] S7, straightening, sawing and sizing finished bars;

[0033] The mechanical properties of TUAg0.1, φ85mm bars were tested, and the test results were Rm322, 325MPa, A16%, 16%, which meet the requirements for conductive screws of nuclear power units.

[0034] The parts not described in detail in the present invention are prior art, so the present invention does not describe them in detail.

Claims

1. A method for producing a large-diameter, high-strength oxygen-free silver-copper rod for a nuclear power unit, wherein the diameter of the oxygen-free silver-copper rod is φ70 mm to φ85 mm, characterized in that: The method comprises the following steps: Cast oxygen-free silver-copper alloy solid round ingots, ingot diameter φ360mm, sawn into single ingots with a length of 500mm-550mm; Heat the sawn ingot to 740-780°C; The heated ingot is extruded to obtain an extruded rod blank with a length of 3-5 meters; Straighten the extruded rods to a straightness of ≤3mm / m; The stretching chuck is made by machining one end of the straightened extruded rod blank. The shape of the stretching chuck includes: a chuck cylindrical section with a length of 150mm; a shoulder conical section with a length of 100-120mm; The extruded rod is subjected to continuous multi-pass stretching processing, the number of passes is 4, and the diameter reduction of each pass matches the stretching capacity of the stretching equipment and the plasticity of the material; The finished bars are straightened, sawed to length and finished to obtain large-diameter high-strength oxygen-free silver-copper bars of φ70~φ85mm for nuclear power units that meet the requirements.

2. The method for producing a large-diameter, high-strength oxygen-free silver-copper rod for a nuclear power unit according to claim 1, characterized in that: The diameter of the extruded rod obtained after the extrusion is φ95-φ110mm.

3. A method for producing a large-diameter, high-strength, oxygen-free silver-copper rod for a nuclear power unit according to claim 1 or 2, characterized in that: In the continuous multi-pass stretching process, the diameter reduction in each pass is 5-10 mm.

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