Pure nickel pipe production process

Abstract

The invention provides a pure nickel pipe production process, and relates to the technical field of non-ferrous metal processing, the pure nickel pipe production process comprises the following steps: S1, material preparation: the pure nickel pipe comprises the following components in percentage by mass: 0.005-0.015% of C, 0.02-0.03% of Si, 1.15-2.00% of Mn, 0.01-0.02% of Al, 0.1-0.2% of Ti and 0.05-0.08% of Ni-Mg, the sum of the above components is 100%, and raw materials are weighed according to the components; the raw materials are added into a smelting furnace to be subjected to vacuum induction smelting, and then electroslag remelting is conducted to obtain a cast ingot; s3, forging is conducted, specifically, the cast ingot is heated and forged into a solid billet; step S4, polishing is carried out; s5, perforating: heating the turned blank, and extruding and perforating the blank into a hollow pipe blank; s6, coping is conducted; step S7, rolling; and S8, heat treatment. Trace elements are added through a vacuum melting process to cast high-quality cast ingots, electroslag remelting is carried out for further clean smelting, a cold machining process and a finished product heat treatment system are optimized after hot forging, and the comprehensive performance of the pipe is improved.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal processing, in particular to a production process of pure nickel pipes. Background Art

[0002] Pure nickel pipes are widely used in aerospace, petrochemical, nuclear energy, electronics and other fields due to their excellent corrosion resistance, high temperature strength, good processing performance and welding performance; however, the traditional pure nickel pipe production process has problems such as low yield rate, high production cost and unstable product performance, which makes it difficult to meet the demand for high-quality pure nickel pipes in high-end fields. Therefore, the development of an efficient, low-cost, high-quality pure nickel pipe production process has become a research hotspot in the industry.

[0003] There are some technical difficulties in the production process of high-quality pure nickel pipes, mainly including the following aspects: 1. The content of impurity elements in the ingot is high, which seriously affects the production of pipes and the quality of finished products; 2. The comprehensive mechanical properties and physical properties of the pipes are uneven; 3. The unreasonable settings of cold and hot processing processes will lead to cracking and other problems during the processing. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a pure nickel pipe production process, which adds trace elements through a vacuum smelting process to melt and cast high-quality ingots, and further purifies the smelting by electroslag remelting, optimizes the cold processing process and the finished product heat treatment system after hot forging, improves the comprehensive performance of the pipe, and produces high-precision, high-strength, high-quality pure nickel pipes.

[0005] The technical solution adopted by the present invention is:

[0006] A pure nickel pipe production process, which includes the following steps:

[0007] Step S1. Ingredients: In terms of mass percentage, the pure nickel pipe includes the following components: C 0.005-0.015%, Si 0.02-0.03%, Mn 1.15-2.00%, Al 0.01-0.02%, Ti 0.1-0.2%, Ni-Mg 0.05-0.08, and the rest is electrolytic nickel Ni and unavoidable impurity elements, the total of the above is 100%, and the raw materials are weighed according to the above components;

[0008] Step S2. Melting and casting: adding the raw materials of step S1 into a melting furnace for vacuum induction melting, and then electroslag remelting to obtain an ingot;

[0009] Step S3. Forging: heating the ingot and forging it into a solid billet with a diameter of Φ86 mm to 159 mm;

[0010] Step S4. Polishing: Polishing the solid billet to obtain a billet;

[0011] Step S5. Perforation: The billet after the polishing in step S4 is heated and extruded to be perforated into a hollow tube billet with a diameter of Φ85mm to 114mm and a wall thickness of 8mm to 11.5mm;

[0012] Step S6. Grinding: Grinding the hollow tube to remove defects generated during the perforation process;

[0013] Step S7. rolling: rolling the hollow tube billet processed in step S6;

[0014] Step S8. Heat treatment: heat-treating the hollow tube blank treated in step S7 under the protection of an inert atmosphere to obtain a pure nickel tube.

[0015] Preferably, in the pure nickel tube production process, the diameter of the ingot in step S2 is φ440-508 mm.

[0016] Preferably, in the pure nickel tube production process, step S3 specifically comprises: heating the ingot once and forging it to a diameter of φ220-250 mm, and then heating and forging it twice to a solid ingot with a diameter of Φ86 mm-159 mm.

[0017] Preferably, in the pure nickel tube production process, the starting forging temperatures of the first heating and the second heating in step S3 are both 1130-1180°C, and the final forging temperatures are both 950-1000°C.

[0018] Preferably, in the pure nickel tube production process, the curvature of the solid billet in step S3 is ≤2 mm / m, and the ovality is ≤1 mm.

[0019] Preferably, in the pure nickel tube production process, the billet in step S4 is 2 to 4 mm smaller in diameter than the solid billet;

[0020] Preferably, in the pure nickel tube production process, the heating temperature in step S5 is 1000-1050°C.

[0021] Preferably, in the pure nickel tube production process, the number of rolling in step S7 is 2-8 times, the rolling processing rate of the intermediate pass is 50-60%, the rolling processing rate of the last pass is 15-20%, and annealing is performed after each rolling pass, the annealing temperature is 800-850° C., and the insulation time is 30-50 min.

[0022] Preferably, in the pure nickel tube production process, the heat treatment temperature in step S8 is 800-850° C. and the insulation time is 30-50 min.

[0023] Advantages of the present invention:

[0024] The pure nickel pipe production process of the present invention adds trace elements to cast high-quality ingots through a vacuum smelting process, further purifies the smelting by electroslag remelting, optimizes the cold processing process and the finished product heat treatment system after hot forging, improves the comprehensive performance of the pipe, and produces high-precision, high-strength, high-quality pure nickel pipes. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] A production process for N02201 pure nickel pipe with a specification of Φ25mm*2mm, which comprises the following steps:

[0028] Step S1. Ingredients: In terms of mass percentage, the pure nickel tube includes the following components: C 0.007%, Si 0.023%, Mn 1.5%, Al 0.013%, Ti 0.15%, Ni-Mg 0.064%, and the rest is electrolytic nickel Ni and unavoidable impurity elements, the total of which is 100%. Raw materials are weighed according to the above components;

[0029] Step S2. Melting and casting: adding the raw materials of step S1 into a melting furnace for vacuum induction melting, the vacuum melting temperature is 1500°C, the pouring temperature is 1515°C, and then electroslag remelting is performed to obtain an ingot with a diameter of φ440 mm, the electroslag remelting slag is 69% CaF2, 15% Al2O3 and 16% CaO, and the smelting current is 11500A;

[0030] Step S3. Forging: heating and forging the ingot into a solid billet with a diameter of Φ86 mm; Step S3 specifically comprises: heating and forging the ingot once to a diameter of φ220 mm, and then heating and forging the ingot twice to a solid billet with a diameter of Φ86 mm, the start forging temperature of the first heating and the second heating are both 1130°C, and the final forging temperature is both 950°C; the curvature of the solid billet is ≤2mm / m, and the ovality is ≤1mm;

[0031] Step S4. Polishing: Polish the solid ingot to obtain a billet, and control the single side to be polished by 1.5 mm;

[0032] Step S5. Perforation: The billet after the polishing in step S4 is heated and extruded to be perforated into a hollow tube billet with a diameter of Φ85mm and a wall thickness of 8mm, and the heating temperature is 1050°C;

[0033] Step S6. Grinding: Grinding the hollow tube to remove harmful defects such as cracks, pits, and peeling generated during the perforation process to ensure the quality of subsequent rolling;

[0034] Step S7. rolling: rolling the hollow tube billet processed in step S6 for 4 times, and the size of the rolled hollow tube billet changes in the order of Φ85mm*8mm→60mm*5mm→48mm*3mm→Φ28mm*2.2mm→Φ25mm*2mm. Annealing is performed after each rolling, and the annealing temperature is 840°C and the holding time is 30min.

[0035] Step S8. Heat treatment: The hollow tube blank treated in step S7 is heat treated under argon protection at a temperature of 850° C. for 35 minutes to obtain a pure nickel tube.

[0036] The pure nickel tube prepared in Example 1 was subjected to composition analysis, comprehensive performance test and finished product ultrasonic flaw detection. The test results are shown in Table 1, Table 2 and Table 3.

[0037] Table 1

[0038]

[0039] Table 2

[0040]

[0041] Table 3

[0042]

[0043] It can be seen from Table 1 that the Φ25mm*2mm N02201 pure nickel pipe treated in Example 1 has uniform chemical composition and low impurity content, which meets the chemical composition requirements of GB / T 5235 for grade N02201 (N5); it can be seen from Table 2 that the mechanical properties of the Φ25mm*2mm N02201 treated in Example 1 are uniform, which meets the mechanical properties requirements of GB / T 2882 for grade N02201 (N5); it can be seen from Table 3 that the cracking of the Φ25mm*2mm N02201 treated in Example 1 is effectively solved, and ultrasonic flaw detection is performed according to GB / T 5777, and the flaw detection yield rate is significantly improved.

[0044] Example 2

[0045] A production process for N6 pure nickel pipe with a specification of Φ45mm*3mm, which comprises the following steps:

[0046] Step S1. Ingredients: In terms of mass percentage, the pure nickel pipe includes the following components: C 0.006%, Si 0.02%, Mn 2.0%, Al 0.015%, Ti 0.14%, Ni-Mg 0.07%, and the rest is electrolytic nickel Ni and unavoidable impurity elements, the total of which is 100%. Raw materials are weighed according to the above components;

[0047] Step S2. Melting and casting: adding the raw materials of step S1 into a melting furnace for vacuum induction melting, the vacuum melting temperature is 1510°C and the pouring temperature is 1520°C; then electroslag remelting is performed to obtain an ingot with a diameter of φ508 mm, the electroslag remelting slag is 69% CaF2, 15% Al2O3 and 16% CaO, and the smelting current is 11500A;

[0048] Step S3. Forging: heating and forging the ingot into a solid billet with a diameter of Φ86 mm; Step S3 specifically comprises: heating and forging the ingot once to a diameter of φ240 mm, and then heating and forging the ingot twice to a solid billet with a diameter of Φ86 mm, the start forging temperature of the first heating and the second heating are both 1150°C, and the final forging temperature is both 950°C; the curvature of the solid billet is ≤2mm / m, and the ovality is ≤1mm;

[0049] Step S4. Polishing: Polish the solid ingot to obtain a billet, and control the single side to be polished by 1.5 mm;

[0050] Step S5. Perforation: The billet after the polishing in step S4 is heated and extruded to be perforated into a hollow tube billet with a diameter of Φ114 mm and a wall thickness of 11.5 mm, and the heating temperature is 1050°C;

[0051] Step S6. Grinding: Grinding the hollow tube to remove harmful defects such as cracks, pits, and peeling generated during the perforation process to ensure the quality of subsequent rolling;

[0052] Step S7. rolling: rolling the hollow tube billet processed in step S6 for 4 times, and the size of the rolled hollow tube billet changes in the order of Φ114mm*11.5mm→89mm*7mm→60mm*5.2mm→Φ48mm*3.2mm→Φ45mm*3mm. Annealing is performed after each rolling, and the annealing temperature is 850°C and the holding time is 35min.

[0053] Step S8. Heat treatment: The hollow tube blank treated in step S7 is heat treated under argon protection at a temperature of 840° C. for 30 minutes to obtain a pure nickel tube.

[0054] The pure nickel tube prepared in Example 2 was subjected to composition analysis, comprehensive performance testing and finished product ultrasonic flaw detection. The test results are shown in Tables 4, 5 and 6.

[0055] Table 4

[0056]

[0057] Table 5

[0058]

[0059] Table 6

[0060]

[0061] It can be seen from Table 4 that the Φ43mm*3mm N6 pure nickel tube treated in Example 2 has uniform chemical composition and low impurity content, which meets the requirements of GB / T 5235 for the chemical composition of grade N6; it can be seen from Table 5 that the mechanical properties of the Φ45mm*3mm N6 treated in Example 2 are uniform, which meets the requirements of GB / T 2882 for the mechanical properties of grade N6; it can be seen from Table 6 that the cracking of the Φ45mm*3mm N02201 treated in Example 2 is effectively solved, and ultrasonic flaw detection is performed according to GB / T 5777, and the flaw detection yield rate is significantly improved.

[0062] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A pure nickel tube production process, characterized in that: The following steps are involved: Step S1. Ingredients: In terms of mass percentage, the pure nickel tube includes the following raw materials: C 0.005-0.015%, Si 0.02-0.03%, Mn 1.15-2.00%, Al 0.01-0.02%, Ti 0.1-0.2%, Ni-Mg 0.05-0.08, and the rest is electrolytic nickel Ni and unavoidable impurity elements, the total of the above is 100%, and the raw materials are weighed according to the above components; Step S2. Melting and casting: adding the raw materials weighed in step S1 into a melting furnace for vacuum induction melting, and then electroslag remelting to obtain an ingot; Step S3. Forging: heating the ingot and forging it into a solid billet with a diameter of Φ86 mm to 159 mm; Step S4. Polishing: Polishing the solid billet to obtain a billet; Step S5. Perforation: The billet after the polishing in step S4 is heated and extruded to be perforated into a hollow tube billet with a diameter of Φ85mm to 114mm and a wall thickness of 8mm to 11.5mm; Step S6. Grinding: Grinding the hollow tube to remove defects generated during the perforation process; Step S7. rolling: rolling the hollow tube billet processed in step S6; Step S8. Heat treatment: heat-treating the hollow tube blank treated in step S7 under the protection of an inert atmosphere to obtain a pure nickel tube.

2. The pure nickel tube production process according to claim 1, characterized in that: The diameter of the ingot in step S2 is φ440-508 mm.

3. The pure nickel tube production process according to claim 1, characterized in that: Step S3 specifically comprises: heating the ingot once and forging it to a diameter of φ220-250 mm, and then heating and forging it twice to a solid billet with a diameter of Φ86 mm-159 mm.

4. The pure nickel tube production process according to claim 3, characterized in that: In step S3, the starting forging temperature of the primary heating and the secondary heating are both 1130-1180°C, and the final forging temperature is both 950-1000°C.

5. The pure nickel tube production process according to claim 1, characterized in that: In step S3, the curvature of the solid billet forging is ≤2 mm / m, and the ovality is ≤1 mm.

6. The pure nickel tube production process according to claim 1, characterized in that: In step S4, the diameter of the billet is 2 to 4 mm smaller than the diameter of the solid billet.

7. The pure nickel tube production process according to claim 1, characterized in that: The heating temperature in step S5 is 1000-1050°C.

8. The pure nickel tube production process according to claim 1, characterized in that: The number of rolling in step S7 is 2-8 times, the rolling processing rate of the intermediate pass is 50-60%, and the rolling processing rate of the last pass is 15-20%. Annealing is performed after each rolling pass, the annealing temperature is 800-850°C, and the insulation time is 30-50min.

9. The pure nickel tube production process according to claim 1, characterized in that: In step S8, the heat treatment temperature is 800-850° C., and the insulation time is 30-50 min.

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