Preparation method of nuclear-grade zirconium-niobium intermediate alloy wire

Abstract

The invention discloses a preparation method of a nuclear-grade zirconium-niobium intermediate alloy wire. The zirconium-niobium intermediate alloy wire consists of the following components in percentage by mass: 15-75% of Nb and the balance of Zr and inevitable impurities. The method comprises the following steps that firstly, sponge zirconium and a niobium block are subjected to vacuum self-consuming electric arc melting, and a bar billet is obtained through forging; secondly, the bar billet is rolled at the temperature of 850-950 DEG C through a rolling mill, and after annealing is conducted under the argon condition, scalping and cold rolling are conducted to obtain a wire billet; and thirdly, the wire blank is scalped, intermediate vacuum annealing and polishing are conducted in multi-pass cold drawing, and the zirconium-niobium intermediate alloy wire is obtained. According to the method, the Nb element content of the zirconium-niobium intermediate alloy and the rolling temperature of the rolling mill are controlled, the process of combining cold rolling and multi-pass cold drawing is adopted, alloy flowing on the surface of the wire and alloy flowing on the core can be synchronous and uniform, the zirconium-niobium intermediate alloy wire with good quality is obtained, and the method is suitable for the technical field of metal material machining.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material processing, and in particular relates to a method for preparing a nuclear-grade zirconium-niobium master alloy wire. Background Art

[0002] Since the melting point of metallic niobium is as high as 2477°C, which is 600°C higher than that of zirconium, the traditional zirconium-niobium alloy material preparation process directly introduces elemental niobium for smelting, which easily introduces high-melting-point niobium ingots and produces metallurgical defects such as element segregation. In addition, there are problems such as complex process and difficulty in controlling impurity elements.

[0003] By preparing zirconium-niobium master alloys to reduce the melting point difference with the matrix zirconium, the problems of inclusions and segregation that are prone to occur in the preparation process of existing zirconium-niobium alloy materials can be effectively solved; at the same time, the purpose of simplifying the production process and reducing manufacturing costs can be achieved. Zirconium-niobium master alloys are crucial to improving the quality of zirconium alloy products, and have gradually become a necessary raw material for the preparation of high-quality, high-performance zirconium-niobium alloys. Commonly used granular zirconium-niobium master alloy products are usually made by cutting wires. In order to obtain granular zirconium-niobium master alloy products with qualified chemical composition, appearance and size, it is necessary to prepare high-quality wires of zirconium-niobium master alloys.

[0004] In the prior art, zirconium-niobium master alloys are prone to defects such as shrinkage, pores and delamination during drawing; and the use of traditional pickling for surface treatment will result in poor surface quality of the wire. Therefore, how to produce high-quality zirconium-niobium master alloy wires has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a method for preparing a nuclear-grade zirconium-niobium master alloy wire. The preparation method controls the Nb element content in the zirconium-niobium master alloy wire, controls the rolling temperature of the rolling mill, and adopts a process combining cold rolling and multi-pass cold drawing to achieve synchronous and uniform flow of alloy on the wire surface and in the core, thereby obtaining a zirconium-niobium master alloy wire of good quality, and solves the problem of defects such as shrinkage, pores and delamination of the zirconium-niobium master alloy in the prior art during drawing.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a nuclear-grade zirconium-niobium master alloy wire, characterized in that the zirconium-niobium master alloy wire is composed of the following components by mass fraction: Nb 15% to 75%, and the balance is Zr and unavoidable impurities; the preparation method comprises the following steps:

[0007] Step 1: using zirconium sponge and niobium block as raw materials, obtaining zirconium-niobium master alloy ingots by vacuum consumable arc melting, and then forging to obtain rod blanks;

[0008] Step 2: The rod blank obtained in step 1 is rolled into a strip by a rolling machine at 850° C. to 950° C., annealed under argon gas, peeled, and then cold-rolled to obtain a wire blank;

[0009] Step 3: After the wire blank obtained in step 2 is peeled, it is subjected to multiple cold drawing, and intermediate vacuum annealing and polishing are performed during the multiple cold drawing to obtain a zirconium-niobium master alloy wire.

[0010] The present invention controls the temperature of the rolling mill to be 850° C. to 950° C. Under this temperature condition, the zirconium-niobium master alloy bar blank has good machinability, can reduce the difficulty of rolling, reduce the probability of defects such as pores in the rolled bar, and thus reduce the internal defects of the zirconium-niobium master alloy wire.

[0011] The above-mentioned method for preparing a nuclear-grade zirconium-niobium master alloy wire is characterized in that the annealing temperature in step 2 is 700° C. to 800° C., and the annealing holding time is 0.5 h to 2 h.

[0012] The present invention can improve the phase structure and uniform organization inside the rolled strip and reduce the internal stress generated after rolling by the rolling mill by controlling the annealing temperature at 700°C to 800°C and the holding time at 0.5h to 2h, so that the rolled strip can be smoothly cold rolled.

[0013] The above-mentioned method for preparing a nuclear-grade zirconium-niobium master alloy wire is characterized in that the multi-pass cold drawing in step three adopts a roller die wire drawing process, and ultrasonic flaw removal is performed before the multi-pass cold drawing.

[0014] The present invention adopts a roller die wire drawing process to perform cold drawing, and screens qualified wire blanks through ultrasonic flaw removal, thereby reducing the probability of defects in the wire material during the drawing process.

[0015] The above-mentioned method for preparing a nuclear-grade zirconium-niobium master alloy wire is characterized in that the intermediate vacuum annealing in step three is as follows: heating to 600°C to 750°C and keeping for 0.5h to 1h, then cooling to below 150°C and taking out of the furnace.

[0016] The present invention performs vacuum annealing between two multi-pass cold drawing processes and controls the temperature of vacuum annealing to reduce the internal stress generated after the first multi-pass cold drawing process, so that the second multi-pass cold drawing process can be carried out smoothly, further reducing the probability of defects, and obtaining a zirconium-niobium master alloy wire with good surface and internal quality.

[0017] The present invention comprehensively designs the heat treatment temperature in each process according to the element composition, diameter size and deformation amount of each process of the zirconium-niobium master alloy.

[0018] The above-mentioned method for preparing a nuclear-grade zirconium-niobium master alloy wire is characterized in that the multiple cold drawing in step three is followed by ultrasonic cleaning, drying and polishing.

[0019] The above-mentioned method for preparing a nuclear-grade zirconium-niobium master alloy wire is characterized in that the zirconium-niobium master alloy wire in step three is a straight wire or a coiled wire, and the diameter of the zirconium-niobium master alloy wire is 1.0 mm to 5.0 mm.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention continuously reduces the diameter of the zirconium-niobium master alloy by sequentially performing hot rolling and cold rolling, distributes the deformation amount to each step, reduces the deformation amount of the final cold drawing process, and makes the wire preparation easier; by controlling the Nb element content in the zirconium-niobium master alloy wire, controlling the rolling temperature of the rolling mill, and adopting a process combining cold rolling and multi-pass cold drawing, the synchronous and uniform flow of the wire surface and the core alloy is achieved; in addition, the deformation amount of each stage process is small, which is conducive to reducing the defects generated in the preparation process, and finally obtaining the zirconium-niobium master alloy wire without defects such as shrinkage tail, pores and delamination.

[0022] 2. The present invention can reduce the oxidation degree of the zirconium-niobium master alloy wire by controlling the annealing process to argon or vacuum conditions and performing peeling treatment on the materials at each stage, thereby avoiding the use of traditional pickling for surface treatment to obtain a zirconium-niobium master alloy wire with excellent surface quality.

[0023] 3. The present invention anneals the zirconium-niobium master alloy during the preparation process to reduce internal stress, thereby further reducing the difficulty of forming the zirconium-niobium master alloy wire, thereby reducing the probability of defects in the zirconium-niobium master alloy wire and improving the yield rate.

[0024] 4. The zirconium-niobium master alloy wire prepared by the present invention has a smooth surface, qualified macrostructure, controllable diameter, a wide range of applications, and good practical performance.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a physical picture of the ZrNb45 intermediate alloy wire in Example 1 of the present invention.

[0027] Figure 2 This is a low-magnification microstructure diagram of the ZrNb45 intermediate alloy wire in Example 1 of the present invention.

[0028] Figure 3 This is a physical picture of the ZrNb15 intermediate alloy wire in Example 2 of the present invention.

[0029] Figure 4 This is a physical picture of the ZrNb75 intermediate alloy wire in Example 3 of the present invention. DETAILED DESCRIPTION

[0030] Example 1

[0031] The zirconium-niobium master alloy wire of this embodiment is composed of the following components by mass content: Nb 45%, Hf 0.008%, O 0.14%, Ta 0.1%, Fe 0.15%, Si 0.01%, and the balance is Zr and unavoidable impurities;

[0032] The preparation method of this embodiment comprises the following steps:

[0033] Step 1: Using zirconium sponge and niobium blocks with a mass purity of more than 99.9% as raw materials, obtaining zirconium-niobium master alloy ingots by vacuum consumable arc melting, and then forging to obtain rod blanks;

[0034] Step 2: The rod blank obtained in step 1 is made into a rolled bar by a rolling machine at 900° C., and then heated to 750° C. for 1 hour under argon filling conditions for annealing, and then cold-rolled after peeling to obtain a wire blank;

[0035] Step three, peel the wire blank obtained in step two, remove defects by ultrasonic treatment, cold draw it for three times by roller die wire drawing process, vacuum anneal and polish it, then cold draw it for three times, and finally ultrasonically clean, dry and polish it with a scouring pad to obtain a ZrNb45 intermediate alloy wire with a diameter of 3 mm; the vacuum annealing process is: heating to 700°C and keeping it for 1h, then cooling to 150°C and taking it out of the furnace; the ZrNb45 intermediate alloy wire is a straight wire.

[0036] The ZrNb45 master alloy wire prepared in this embodiment is as follows Figure 1 As shown, the appearance quality is good; the low-power microstructure analysis of the ZrNb45 intermediate alloy wire is carried out, as shown Figure 2 As shown, there is no shrinkage tail, crack, pore, delamination or Nb infusible material in the macrostructure, which fully meets the use requirements.

[0037] Example 2

[0038] The zirconium-niobium master alloy wire of this embodiment is composed of the following components by mass content: Nb 15%, Hf 0.01%, O 0.12%, Ta 0.1%, Fe 0.1%, Si 0.006%, and the balance is Zr and unavoidable impurities;

[0039] The preparation method of this embodiment comprises the following steps:

[0040] Step 1: Using zirconium sponge and niobium blocks with a mass purity of more than 99.9% as raw materials, obtaining zirconium-niobium master alloy ingots by vacuum consumable arc melting, and then forging to obtain rod blanks;

[0041] Step 2: The rod blank obtained in step 1 is made into a rolled strip by a rolling machine at 850° C., and then heated to 700° C. for 2 h under argon filling to anneal, and then cold-rolled after peeling to obtain a wire blank;

[0042] Step three, peel the wire blank obtained in step two, remove defects by ultrasonic treatment, cold draw it for 4 times by roller die wire drawing process, vacuum anneal and polish it, then cold draw it for 3 times, and finally ultrasonically clean, dry and polish it with a scouring pad to obtain a ZrNb15 intermediate alloy wire with a diameter of 1 mm; the vacuum annealing process is: heating to 600°C and keeping it for 1h, then cooling to 150°C and taking out of the furnace; the ZrNb15 intermediate alloy wire is a coiled wire.

[0043] The ZrNb15 master alloy wire prepared in this embodiment is as follows Figure 3 As shown, the appearance quality is good; after testing, there is no shrinkage tail, crack, pore, delamination and Nb infusible matter in the macrostructure, which fully meets the use requirements.

[0044] Example 3

[0045] The zirconium-niobium master alloy wire of this embodiment is composed of the following components by mass content: Nb 75%, Hf 0.007%, O 0.13%, Ta 0.08%, Fe 0.13%, Si 0.008%, and the balance is Zr and unavoidable impurities;

[0046] The preparation method of this embodiment comprises the following steps:

[0047] Step 1: Using zirconium sponge and niobium blocks with a mass purity of more than 99.9% as raw materials, obtaining zirconium-niobium master alloy ingots by vacuum consumable arc melting, and then forging to obtain rod blanks;

[0048] Step 2: The rod blank obtained in step 1 is made into a rolled bar by a rolling machine at 950° C., and then heated to 800° C. for 0.5 h under argon filling for annealing, and then cold-rolled after peeling to obtain a wire blank;

[0049] Step three, peel the wire blank obtained in step two, remove defects by ultrasonic treatment, cold draw it for three times by roller die wire drawing process, vacuum anneal and polish it, then cold draw it for two times, and finally ultrasonically clean, dry and polish it with a scouring pad to obtain a ZrNb75 intermediate alloy wire with a diameter of 5 mm; the vacuum annealing process is: heating to 750°C and keeping it for 0.5h, then cooling to 150°C and taking it out of the furnace; the ZrNb75 intermediate alloy wire is a straight wire.

[0050] The ZrNb75 master alloy wire prepared in this embodiment is as follows Figure 4 As shown, the appearance quality is good; after testing, there is no shrinkage tail, crack, pore, delamination and Nb infusible matter in the macrostructure, which fully meets the use requirements.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a nuclear-grade zirconium-niobium master alloy wire, characterized in that: The zirconium-niobium master alloy wire is composed of the following components by mass fraction: 15% to 75% Nb, and the balance is Zr and inevitable impurities; the preparation method comprises the following steps: Step 1: using zirconium sponge and niobium block as raw materials, obtaining zirconium-niobium master alloy ingots by vacuum consumable arc melting, and then forging to obtain rod blanks; Step 2: The rod blank obtained in step 1 is rolled into a strip by a rolling machine at 850° C. to 950° C., annealed under argon gas, peeled, and then cold-rolled to obtain a wire blank; Step 3: After the wire blank obtained in step 2 is peeled, it is subjected to multiple cold drawing, and intermediate vacuum annealing and polishing are performed during the multiple cold drawing to obtain a zirconium-niobium master alloy wire.

2. The method for preparing a nuclear-grade zirconium-niobium master alloy wire according to claim 1, characterized in that: The annealing temperature in step 2 is 700° C. to 800° C., and the annealing holding time is 0.5 h to 2 h.

3. The method for preparing a nuclear grade zirconium-niobium master alloy wire according to claim 1, characterized in that: The multi-pass cold drawing in step three adopts a roller die wire drawing process, and ultrasonic flaw removal is performed before the multi-pass cold drawing.

4. The method for preparing a nuclear-grade zirconium-niobium master alloy wire according to claim 1, characterized in that: The system of intermediate vacuum annealing in step three is: heating to 600°C to 750°C and keeping it for 0.5h to 1h, then cooling to below 150°C and taking out of the furnace.

5. The method for preparing a nuclear-grade zirconium-niobium master alloy wire according to claim 1, characterized in that: After the multiple cold drawing steps in step 3, ultrasonic cleaning, drying and polishing are performed in sequence.

6. The method for preparing a nuclear-grade zirconium-niobium master alloy wire according to claim 1, characterized in that: The zirconium-niobium master alloy wire in step 3 is a straight wire or a coiled wire, and the diameter of the zirconium-niobium master alloy wire is 1.0 mm to 5.0 mm.

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