Gradient heating temperature control method suitable for high nickel-copper alloy cast ingot extrusion preparation process

Abstract

The invention provides a gradient heating temperature control method suitable for a high-nickel-copper alloy ingot extrusion preparation process, belongs to the technical field of metal material pressure processing, and solves the problems that a high-nickel-copper alloy is difficult to form and is easy to overburn or cannot be extruded due to a narrow hot processing temperature window in a hot extrusion process. The temperatures of the induction coils of the heating furnace are set respectively, so that a gradient temperature field from low temperature to high temperature is formed; the method comprises the following steps: performing gradient heating on a high-nickel copper alloy cast ingot, detecting the surface temperature of the cast ingot by adopting infrared temperature measuring equipment, suspending heating in an induction furnace when the temperature of the cast ingot reaches a set process temperature, and extruding until the whole cast ingot reaches a temperature state suitable for extrusion; and continuously monitoring the surface state of the cast ingot in the extrusion process to finally obtain the product. According to the method, the extruded product with the surface quality and the size specification meeting the requirements and the uniform internal structure is obtained through accurate temperature gradient regulation and control.

Description

Technical Field

[0001] This invention belongs to the field of metal material pressure processing technology, specifically relating to a gradient heating temperature control method suitable for the extrusion preparation process of high-nickel copper alloy ingots. Background Technology

[0002] High-nickel copper alloys (nickel content ranging from 30% to 58% by mass, with the balance of Cu) possess excellent mechanical properties, corrosion resistance, and high wear resistance, and are widely used in marine engineering, oil extraction, and aerospace. In recent years, with the iterative development of related technologies, the market demand for high-nickel copper alloy products has become increasingly urgent.

[0003] However, high-nickel copper alloys, as high-strength and highly corrosion-resistant copper alloys, exhibit significantly higher mechanical properties than pure copper, with superior work hardening tendency and high-temperature deformation resistance. Furthermore, as the Ni content increases, the thermal conductivity of the alloy ingot decreases, further increasing the difficulty of hot working. When using extrusion processes to produce high-nickel copper alloy tubes, bars, and profiles, the narrow process window often results in low yields, severely restricting the production and supply of these alloy products. Therefore, effectively improving the extrusion yield of high-nickel copper alloys has become a critical issue that urgently needs to be addressed in production.

[0004] Studies have shown that the main reason for the difficulty in extruding high-nickel copper alloys and their poor formability is their narrow hot working temperature range, approximately 940℃–980℃. Furthermore, the higher the nickel content, the higher the required extrusion temperature. During extrusion, if the ingot heating temperature is too high, surface overheating and oxidation can easily occur, leading to cracking of the extruded product. If the temperature is too low, "stuck ingot" or even extrusion failure can easily occur, affecting not only the forming effect but also potentially threatening equipment safety. In addition, extending the ingot heating time in the furnace to ensure temperature uniformity can cause coarsening of the product's microstructure and a decrease in mechanical properties.

[0005] Therefore, the main starting point for this gradient heating temperature control method is to achieve precise control of the heating process of high-nickel copper alloy ingots within a narrow hot working temperature range, so as to ensure the smooth forming of products and meet the technical requirements of mechanical properties, dimensional accuracy and microstructure. Summary of the Invention

[0006] The purpose of this invention is to provide a gradient heating temperature control method suitable for the extrusion preparation process of high-nickel copper alloy ingots, so as to solve the problems of difficult forming, overheating or inability to extrude high-nickel copper alloys due to the narrow hot working temperature window during hot extrusion.

[0007] The technical solution of this invention is: a gradient heating temperature control method suitable for the extrusion preparation process of high-nickel copper alloy ingots, comprising the following steps: Step 1: Set the temperature of the 6 sets of induction coils in the copper ingot heating furnace of the 55MN extruder. Set the area of ​​coils 1 to 4 as the low temperature zone and the area of ​​coils 5 and 6 as the high temperature zone, thereby forming a gradient temperature field from low temperature to high temperature. The copper ingot heating furnace for the 55MN extrusion press is model NIB5602 / 310-1300; The temperature setting range for coil #1 is 260-280℃, for coil #2 it is 480-520℃, for coil #3 it is 700-740℃, for coil #4 it is 800-850℃, for coil #5 it is 890-920℃, and for coil #6 it is 940-980℃. Step 2: Feed the high-nickel copper alloy ingot into the induction heating furnace at an overall feeding speed of 30mm / min-50mm / min to implement gradient heating. During the heating process, monitor the ingot temperature in the coil areas of No. 4, No. 5 and No. 6 in real time to prevent the ingot from burning due to local overheating. Step 3: Use an infrared thermometer to detect the surface temperature of the ingot. The surface temperature in this area must not exceed 980℃ to avoid overheating and oxidation of the ingot; the infrared thermometer is Raytek Raynger3iplus. Step 4: When the ingot temperature reaches the set process temperature during the heating process of coils #5 and #6, the induction furnace needs to pause heating and allow the ingot to stand in the furnace for 3 minutes to heat evenly. Then, the heating is restarted. The total residence time of the ingot in the high-temperature zone should be controlled between 20 and 50 minutes. Too long a residence time can easily lead to extrusion cracks; too short a residence time will result in a large temperature gradient between the core and the surface of the ingot, uneven heating, and thus cause "ingot jamming" or extrusion difficulties. Repeat this operation 3-5 times, with each heating stop interval controlled at 3 minutes, until the ingot reaches a suitable temperature for extrusion; Step 5: Continuously monitor the surface condition of the ingot during the extrusion process. If the surface color of the ingot turns gray, the temperature should be detected immediately using an infrared device. If the temperature is below 940℃, the extrusion should be stopped, the ingot should be water-cooled, and then reloaded into the furnace for extrusion. The final product is a high-nickel copper alloy tube, bar, or profile product with qualified mechanical properties, dimensional accuracy, and uniform structure.

[0008] As a further improvement of the present invention, in step one, the temperature setting range error of coils 1 to 6 is ±5℃.

[0009] As a further improvement of the present invention, in step one, the temperature of the high-temperature zone is not lower than 940°C.

[0010] As a further improvement of the present invention, in step two, the nickel mass percentage content in the high-nickel copper alloy ingot is not less than 30%, the optimal mass percentage range is 30%-58%, and the balance is copper.

[0011] As a further improvement of the present invention, in step four, the process temperature is set to 940-980℃.

[0012] The beneficial effects of this invention are as follows: This invention divides the six sets of induction coils in the heating furnace into low-temperature and high-temperature zones, constructing a continuous gradient temperature field from 260-280℃ to 940-980℃. This not only adapts to the poor thermal conductivity of high-nickel copper alloys, preventing thermal stress cracks in the ingots due to sudden heating, but also strictly limits the heating temperature to the hot working window of 940-980℃ through a temperature difference control accuracy of ±5℃. This avoids the problems of overheating and oxidation caused by excessively high temperatures and "stuck ingots" caused by excessively low temperatures from the source, laying the foundation for the stability of the forming process.

[0013] This invention addresses the difference in thermal conductivity between the core and surface of high-nickel copper alloys by employing an intermittent operation of "heating-static homogenization-reheating," coupled with precise control of the dwell time in the high-temperature zone for 20-50 minutes. This ensures that heat is fully transferred to the core of the ingot, reducing the internal and external temperature gradient and preventing "ingot jamming" caused by uneven heating during extrusion. It also effectively inhibits grain coarsening. Compared to continuous heating, intermittent homogenization reduces the time accumulated for grain growth at high temperatures, keeping the product grain size ≤60μm and ensuring stable mechanical properties.

[0014] This invention monitors the temperature of coils 4#-6# in real time during the heating stage and uses infrared thermometers to limit the surface temperature to ≤980℃. During the extrusion stage, it observes the surface color and rechecks the temperature, forming a closed-loop process of "setting-monitoring-adjustment". This invention specifically solves the problems of local overheating and easy oxidation of high-nickel copper alloys and rapid temperature loss during the extrusion process, further reducing the forming defect rate and improving process reliability.

[0015] The adjustable parameters of ingot feeding speed, nickel content adaptation, and product specifications in the process of this invention enable it to meet the extrusion requirements of high-nickel copper alloys with different nickel contents and sizes. Simultaneously, the emergency handling mechanism of the water-cooled reloading furnace reduces production losses caused by single temperature fluctuations, indirectly improving the yield and aligning with the actual needs of industrial production.

[0016] This invention constructs a gradient temperature field using an induction heating furnace to achieve precise control of the ingot heating process. Its core innovation lies in employing a gradient heating strategy that combines zoned temperature control, intermittent heating, and multi-round homogenization to ensure the ingot reaches a homogeneous microstructure and suitable temperature before extrusion. This method systematically solves the core pain points of narrow hot working temperature windows and high forming difficulty in high-nickel copper alloys through the synergistic effect of "gradient heating to reduce stress, intermittent homogenization to homogenize microstructure, precise temperature measurement to prevent defects, and adaptive adjustment to expand the range." Ultimately, it achieves simultaneous compliance with product dimensional accuracy, microstructure uniformity, and mechanical properties, thereby effectively improving the extrusion quality of high-nickel copper alloy tubes, bars, and profiles, ensuring that product dimensional accuracy and internal microstructure uniformity meet technical requirements. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the coil distribution in the induction heating furnace of the present invention; Figure 2 This is one of the metallographic images of the high-nickel copper alloy prepared in Example 1 of this invention; Figure 3 This is one of the metallographic images of the high-nickel copper alloy prepared in Example 1 of this invention; Figure 4 This is one of the metallographic images of the high-nickel copper alloy prepared in Example 2 of this invention; Figure 5 This is one of the metallographic images of the high-nickel copper alloy prepared in Example 2 of this invention; Figure 6 This is one of the metallographic images of the high-nickel copper alloy prepared in Example 3 of this invention; Figure 7 This is one of the metallographic images of the high-nickel copper alloy prepared in Example 3 of this invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown, the coil distribution of the induction heating furnace used in Examples 1-3 is coil #1 to coil #6 from right to left. The ingot moves in the heating furnace from right to left as the inlet and outlet.

[0020] Example 1 The specific process for extruding high-nickel copper alloy bars of grade BFe30-0.7 with a diameter of Φ160mm is as follows: Step 1: Set the temperature of the 6 sets of induction coils of the 55MN extrusion press copper ingot heating furnace of model NIB5602 / 310-1300 respectively. Set the area of ​​coils 1# to 4# as the low temperature zone and the area of ​​coils 5# and 6# as the high temperature zone. The temperature of the high temperature zone is not lower than 940℃, thereby forming a gradient temperature field from low temperature to high temperature. The temperature setting range for coil #1 is 260℃, for coil #2 it is 480℃, for coil #3 it is 700℃, for coil #4 it is 800℃, for coil #5 it is 890℃, and for coil #6 it is 940℃; the temperature setting range error from coil #1 to coil #6 is ±5℃.

[0021] Step 2: Feed the high-nickel copper alloy ingot into the induction heating furnace at an overall feeding speed of 30 mm / min and implement gradient heating. During the heating process, monitor the ingot temperature in the coil areas of No. 4, No. 5 and No. 6 in real time to prevent the ingot from burning due to local overheating. The nickel content in high-nickel copper alloy ingots shall be no less than 30% by mass, with the optimal mass percentage range being 30%, and the balance being copper.

[0022] Step 3: Use an infrared thermometer (Raytek Raynger 3iplus) to detect the surface temperature of the ingot. The surface temperature in this area must not exceed 980℃ to avoid overheating and oxidation of the ingot. Step 4: When the ingot temperature reaches the set process temperature of 940℃ during the heating process of coils #5 and #6, the induction furnace needs to stop heating and allow the ingot to stand in the furnace for 3 minutes to heat evenly. Then, the heating is restarted. The total residence time of the ingot in the high-temperature zone should be controlled within 20 minutes. Too long a residence time can easily lead to extrusion cracks; too short a residence time will result in a large temperature gradient between the core and surface of the ingot, uneven heating, and thus cause "ingot jamming" or extrusion difficulties. Repeat this operation 3 times, with each heating stop interval controlled at 3 minutes, until the ingot reaches a temperature suitable for extrusion and then extrudes it; Step 5: Continuously monitor the surface condition of the ingot during the extrusion process. If the surface color of the ingot turns gray, the temperature should be detected immediately using an infrared device. If the temperature is below 940℃, the extrusion should be stopped, the ingot should be water-cooled, and then reloaded into the furnace for extrusion. The final product is a high-nickel copper alloy tube, bar, or profile product with qualified mechanical properties, dimensional accuracy, and uniform structure, namely a Φ160mm bar of grade BFe30-0.7.

[0023] Metallographic image of the high-nickel copper alloy prepared by the method in Example 1 is shown below. Figure 2 and Figure 3As shown, the high-nickel copper alloy grade is BFe30-0.7 alloy, extrusion specification: Φ160mm, with uniform microstructure and grain size ≤50μm.

[0024] Example 2 The specific process for extruding high-nickel copper alloy tubing of grade BFe30-1-1 with a specification of Φ250×10mm is as follows: Step 1: Set the temperature of the 6 sets of induction coils of the 55MN extrusion press copper ingot heating furnace of model NIB5602 / 310-1300 respectively. Set the area of ​​coils 1# to 4# as the low temperature zone and the area of ​​coils 5# and 6# as the high temperature zone. The temperature of the high temperature zone is not lower than 940℃, thereby forming a gradient temperature field from low temperature to high temperature. The temperature setting range for coil #1 is 270℃, for coil #2 it is 500℃, for coil #3 it is 720℃, for coil #4 it is 825℃, for coil #5 it is 905℃, and for coil #6 it is 960℃; the temperature setting range error from coil #1 to coil #6 is ±5℃.

[0025] Step 2: Feed the high-nickel copper alloy ingot into the induction heating furnace at an overall feeding speed of 40 mm / min and implement gradient heating. During the heating process, monitor the ingot temperature in the coil areas of No. 4, No. 5 and No. 6 in real time to prevent the ingot from burning due to local overheating. The nickel content in high-nickel copper alloy ingots shall be no less than 30% by mass, with the optimal mass percentage range being 44%, and the balance being copper.

[0026] Step 3: Use an infrared thermometer to detect the surface temperature of the ingot. The surface temperature in this area must not exceed 980℃ to avoid overheating and oxidation of the ingot; the infrared thermometer is Raytek Raynger3iplus. Step 4: When the ingot temperature reaches the set process temperature of 960℃ during the heating process of coils #5 and #6, the induction furnace needs to stop heating and allow the ingot to stand in the furnace for 3 minutes to heat evenly. Then, the heating is restarted. The total residence time of the ingot in the high-temperature zone should be controlled at 35 minutes. Too long a residence time can easily lead to extrusion cracks; too short a residence time will result in a large temperature gradient between the core and the surface of the ingot, uneven heating, and thus cause "ingot jamming" or extrusion difficulties. Repeat this operation 4 times, with each heating stop interval controlled at 3 minutes, until the ingot reaches a temperature suitable for extrusion and then extrusion is carried out; Step 5: Continuously monitor the surface condition of the ingot during the extrusion process. If the surface color of the ingot turns gray, the temperature should be detected immediately using an infrared device. If the temperature is below 940℃, the extrusion should be stopped, the ingot should be water-cooled, and then reloaded into the furnace for extrusion. The final product is a high-nickel copper alloy tube, bar, or profile product with qualified mechanical properties, dimensional accuracy, and uniform structure, namely, a Φ250×10mm bar of grade BFe30-1-1.

[0027] Metallographic image of the high-nickel copper alloy prepared by the method in Example 2 is shown below. Figure 4 and Figure 5 As shown, the high-nickel copper alloy grade is BFe30-1-1, extrusion specification: Φ250×10mm, with uniform microstructure and grain size ≤50μm.

[0028] Example 3 The specific process for extruding 6J40 grade (CuNi40 alloy) Φ100mm high-nickel copper alloy bars: Step 1: Set the temperature of the 6 sets of induction coils of the 55MN extrusion press copper ingot heating furnace of model NIB5602 / 310-1300 respectively. Set the area of ​​coils 1# to 4# as the low temperature zone and the area of ​​coils 5# and 6# as the high temperature zone. The temperature of the high temperature zone is not lower than 940℃, thereby forming a gradient temperature field from low temperature to high temperature. The temperature setting range for coil #1 is 280℃, for coil #2 it is 520℃, for coil #3 it is 740℃, for coil #4 it is 850℃, for coil #5 it is 920℃, and for coil #6 it is 980℃; the temperature setting range error from coil #1 to coil #6 is ±5℃.

[0029] Step 2: Feed the high-nickel copper alloy ingot into the induction heating furnace at an overall feeding speed of 50 mm / min and implement gradient heating. During the heating process, monitor the ingot temperature in the coil areas of No. 4, No. 5 and No. 6 in real time to prevent the ingot from burning due to local overheating. The nickel content in high-nickel copper alloy ingots shall be no less than 30% by mass, with the optimal mass percentage range being 58%, and the balance being copper.

[0030] Step 3: Use an infrared thermometer to detect the surface temperature of the ingot. The surface temperature in this area must not exceed 980℃ to avoid overheating and oxidation of the ingot; the infrared thermometer is Raytek Raynger3iplus. Step 4: When the ingot temperature reaches the set process temperature of 980℃ during the heating process of coils #5 and #6, the induction furnace needs to stop heating and allow the ingot to stand in the furnace for 3 minutes to heat evenly. Then, the heating is restarted. The total residence time of the ingot in the high-temperature zone should be controlled within 50 minutes. Too long a residence time can easily lead to extrusion cracks; too short a residence time will result in a large temperature gradient between the core and surface of the ingot, uneven heating, and thus cause "ingot jamming" or extrusion difficulties. Repeat this operation 5 times, with each heating stop interval controlled at 3 minutes, until the ingot reaches a temperature suitable for extrusion and then extrudes it; Step 5: Continuously monitor the surface condition of the ingot during the extrusion process. If the surface color of the ingot turns gray, the temperature should be detected immediately using an infrared device. If the temperature is below 940℃, the extrusion should be stopped, the ingot should be water-cooled, and then reloaded into the furnace for extrusion. The final product is a high-nickel copper alloy tube, bar, or profile with qualified mechanical properties, dimensional accuracy, and uniform structure, namely a Φ100mm bar of grade 6J40 (CuNi40 alloy).

[0031] Metallographic image of the high-nickel copper alloy prepared by the method in Example 3 is shown below. Figure 6 and Figure 7 As shown, the high-nickel copper alloy grade is 6J40 (CuNi40 alloy), extrusion specification: Φ100mm, uniform microstructure, grain size ≤60μm.

[0032] As can be seen from Examples 1-3, by applying a gradient heating temperature control method suitable for the extrusion preparation process of high-nickel copper alloy ingots, high-nickel copper alloy products with qualified dimensions and uniform internal structure can be produced.

[0033] The gradient heating temperature control method described in this invention, through zoned gradient temperature control, intermittent homogenization, and full-process temperature monitoring of the heating furnace of the 55MN extruder, has been successfully adapted to the extrusion process of high-nickel copper alloy ingots with a nickel content of 30%-58%. Figure 1 The coil distribution and temperature gradient design shown provide a structural basis for stable ingot heating. Metallographic images of Examples 1, 2, and 3 all show uniform microstructures with grain sizes ≤60μm and no defects such as overheating or cracks. Furthermore, all three products meet the requirements for mechanical properties and dimensional accuracy, verifying the effectiveness and stability of this method in the extrusion of high-nickel copper alloys of different specifications and nickel contents. This method effectively overcomes the forming bottleneck caused by the narrow hot working temperature window of high-nickel copper alloys, significantly improving the reliability of the extrusion process and the product yield, and possesses good industrial application value.

Claims

1. A gradient heating temperature control method suitable for the extrusion preparation process of high-nickel copper alloy ingots, characterized in that: Includes the following steps: Step 1: Set the temperature of the 6 sets of induction coils in the copper ingot heating furnace of the 55MN extruder. Set the area of ​​coils 1 to 4 as the low temperature zone and the area of ​​coils 5 and 6 as the high temperature zone, thereby forming a gradient temperature field from low temperature to high temperature. The temperature setting range for coil #1 is 260-280℃, for coil #2 it is 480-520℃, for coil #3 it is 700-740℃, for coil #4 it is 800-850℃, for coil #5 it is 890-920℃, and for coil #6 it is 940-980℃. Step 2: Feed the high-nickel copper alloy ingot into the induction heating furnace at an overall feeding speed of 30mm / min-50mm / min to implement gradient heating. During the heating process, monitor the ingot temperature in the coil areas of No. 4, No. 5 and No. 6 in real time to prevent the ingot from burning due to local overheating. Step 3: Use infrared thermometer to detect the surface temperature of the ingot. The surface temperature of this area must not exceed 980℃ to avoid overheating and oxidation of the ingot. Step 4: When the ingot temperature reaches the set process temperature during the heating process of coils #5 and #6, the induction furnace needs to stop heating and let the ingot stand in the furnace for 3 minutes to heat up evenly. Then, the heating is restarted. The total residence time of the ingot in the high-temperature zone is controlled between 20 and 50 minutes. Repeat this operation 3-5 times, with each heating stop interval controlled at 3 minutes, until the ingot reaches a suitable temperature for extrusion; Step 5: Continuously monitor the surface condition of the ingot during the extrusion process. If the surface color of the ingot turns gray, the temperature should be detected immediately using an infrared device. If the temperature is below 940℃, the extrusion should be stopped, the ingot should be water-cooled, and then reloaded into the furnace for extrusion. The final product is a high-nickel copper alloy tube, bar, or profile product with qualified mechanical properties, dimensional accuracy, and uniform structure.

2. The gradient heating temperature control method for the extrusion preparation process of high-nickel copper alloy ingots according to claim 1, characterized in that: In step one, the temperature setting range error for coils #1 to #6 is ±5℃.

3. The gradient heating temperature control method for the extrusion preparation process of high-nickel copper alloy ingots according to claim 1, characterized in that: In step one, the temperature in the high-temperature zone shall not be lower than 940℃.

4. The gradient heating temperature control method for the extrusion preparation process of high-nickel copper alloy ingots according to claim 1, characterized in that: In step two, the nickel content in the high-nickel copper alloy ingot shall not be less than 30% by mass, with the balance being copper.

5. The gradient heating temperature control method for the extrusion preparation process of high-nickel copper alloy ingots according to claim 1, characterized in that: In step four, the process temperature is set to 940-980℃.

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