A copper alloy continuous extrusion die material and a method for manufacturing the same

Abstract

The application discloses a copper alloy continuous extrusion die material and a preparation method thereof. The chemical composition of the die material is as follows: C: 0.47-0.51%, Si: 0.30-0.50%, Mn: 0.30-0.50%, Cr: 3.60-4.00%, Mo: 1.80-2.20%, V: 0.40-0.60%, W: 0.20-0.40%, Co: 0.20-0.40%, B: 0.002-0.005%, P: less than or equal to 0.020%, S: less than or equal to 0.010%, and the balance of Fe and inevitable impurities. The preparation method comprises the following steps: smelting, electroslag remelting, high-temperature homogenization, forging, superfine treatment and spheroidizing annealing. The application optimizes the alloy composition, improves the thermal stability and wear resistance of the die steel on the basis of ensuring high strength and toughness, and meets the use requirements of the copper alloy continuous extrusion die in high temperature, high pressure and high wear.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of die steel, and particularly relates to a copper alloy continuous extrusion die material and a preparation method thereof. BACKGROUND

[0002] Continuous extrusion has many advantages such as low energy consumption, high production efficiency, high dimensional accuracy and continuous production, and is widely used in the fields of building, aviation, transportation and communication. In the continuous extrusion process, the die is subjected to high temperature, high pressure and strong friction, and the die material is required to have high strength and toughness, high wear resistance, good corrosion resistance and thermal fatigue resistance, so as to ensure the stability of the die structure and excellent performance during long-term service. According to statistics, about 50% of the failure of continuous extrusion dies is caused by unreasonable selection of die materials and improper heat treatment process, so the quality of the die material is a key factor determining the service life of the die.

[0003] With the increase of the strength of the copper-aluminum alloy material to be processed and the gradual popularization of high-speed extrusion machines, the requirements for the heat resistance and quality stability of the continuous extrusion die material are becoming higher and higher. There are limited choices for die materials suitable for processing of difficult-to-deform non-ferrous alloys such as electrical copper bars, copper-magnesium alloys and 7-series aluminum alloys at a service temperature of 620 DEG C or above. The quality stability of the high-heat-resistant extrusion die steels such as RM2, Y4, ER8 and HD developed in China needs to be improved, and the current application amount in the market accounts for only about 2% of the total output of die steels. High-end and long-life extrusion die materials still rely heavily on imports.

[0004] Therefore, it is of great practical significance to develop a new type of die material with excellent strength and toughness, which is suitable for the use requirements of high temperature, high pressure and high wear of copper alloy continuous extrusion dies. SUMMARY

[0005] The application aims to provide a copper alloy continuous extrusion die material and a preparation method thereof. Through W and Co alloying design, clean smelting, precise control in the forging process and ultra-fining treatment, the thermal stability and wear resistance of the die steel are improved on the basis of ensuring high strength and toughness, so as to meet the use requirements of high temperature, high pressure and high wear of copper alloy continuous extrusion dies.

[0006] To achieve the above-mentioned purpose, the technical scheme provided by the application is as follows:

[0007] A copper alloy continuous extrusion die material, which has the following chemical composition and mass percentage: C: 0.47-0.51%, Si: 0.30-0.50%, Mn: 0.30-0.50%, Cr: 3.60-4.00%, Mo: 1.80-2.20%, V: 0.40-0.60%, W: 0.20-0.40%, Co: 0.20-0.40%, B: 0.002-0.005%, P≤0.020%, S≤0.010%, and the balance of Fe and inevitable impurities.

[0008] The component design of the copper alloy continuous extrusion die material meets the concept of reducing Cr and increasing Mo, reduces segregation, improves thermal fatigue resistance and thermal stability, appropriately reduces the V content, increases the W and Co content, improves high-temperature strength, wear resistance and tempering stability, adds a small amount of B element, and improves hardenability. The action mechanism of part of the elements is as follows:

[0009] C: C content is the only factor affecting the hardenability of steel, and appropriately increasing the C content is the basis for ensuring the strength, hardness and wear resistance of the material. The C content in the steel is controlled in the range of 0.47-0.51%.

[0010] Cr: In the steel of the present application, Cr mainly functions to ensure the hardenability of the steel, and higher hardenability is a necessary prerequisite for producing large-section die materials. Cr 23 C6 secondary carbide can improve the high-temperature strength and wear resistance of the steel, but compared with Mo-containing and V-containing carbides, its stability is slightly poor, and with the increase of tempering temperature, Cr 23 C6 secondary carbide gradually coarsens, reducing the tempering hardness. Accordingly, the Cr content is controlled in the range of 3.60-4.00%.

[0011] Mo and W: In the steel of the present application, Mo and W mainly function to strengthen the secondary hardening effect during tempering, improve thermal strength and red hardness. Mo is slightly inferior to W in improving wear resistance and thermal stability, but Mo element can ensure higher toughness of the die steel, therefore, considering the high toughness requirement of continuous extrusion die, a small amount of W is added to replace Mo, which has the advantages of strength and toughness of die material and economy, the Mo content in the steel of the present application is controlled in the range of 1.80-2.20%, and the W content is controlled in the range of 0.20-0.40%.

[0012] Co: In the present application, the main function of Co is to promote the precipitation of Mo and W carbides from martensite during tempering, improve the secondary hardening effect, and thus ensure the thermal strength and high-temperature wear resistance of the die material. However, since Co element can reduce the hardenability of the steel and significantly reduce the plasticity and toughness of the steel, the Co content in the steel of the present application is controlled in the range of 0.20-0.40%.

[0013] V: V is a strong carbide forming element, the secondary precipitated MC type carbide is relatively stable, and is not easy to gather and grow, thereby improving the solid solution strengthening effect of the steel. The unmelted V carbide is dispersedly distributed on the matrix, strongly pins the grain boundary, obviously refines the grain, and can significantly improve the high strength and toughness and tempering stability of the die steel. The V content in the steel is controlled in the range of 0.40-0.60%.

[0014] Si: Si is not the main strengthening element of the steel, Si is the main element causing banding segregation, therefore, in order to improve the material composition uniformity and reduce element segregation, the Si content in the steel is controlled in the range of 0.30-0.50%.

[0015] Mn: Mn is not the main strengthening element of the steel, and is usually added as a deoxidizer, has great affinity with S, forms MnS with certain plasticity, reduces the risk of hot brittleness, and the Mn content is controlled in the range of 0.30-0.50%.

[0016] B: In the steel, the main role of B element is to improve the hardenability and high temperature strength, and the B content is controlled in the range of 0.002-0.005%.

[0017] The application also provides a preparation method of the copper alloy continuous extrusion die material, comprising the following steps:

[0018] (1) Melting: the ingredients are melted, and then subjected to secondary refining, vacuum degassing and casting into an electrode rod;

[0019] (2) Electroslag remelting: the electrode rod is subjected to surface grinding or shot blasting treatment, and then electroslag remelting is carried out, the obtained electroslag ingot is stress relieved at a heating temperature of 700-750 DEG C for 2-4 h;

[0020] (3) High-temperature homogenization: the electroslag ingot is subjected to high-temperature homogenization treatment at a heating temperature of 1240-1260 DEG C for (0.25-0.35) x D hours, wherein D is the diameter of the electroslag ingot in cm, and then furnace cooling is carried out to a forging temperature of 1160-1180 DEG C;

[0021] (4) Forging: the initial forging temperature is 1100-1140 DEG C, the final forging temperature is 820-850 DEG C, air cooling or water mist cooling is carried out to 150-200 DEG C after forging, and then slow cooling or sand burying slow cooling is carried out;

[0022] (5) Super-fining treatment: the obtained forged material is subjected to super-fining treatment, normalizing is carried out at a heating temperature of 1100-1120 DEG C for 2-3 h, air cooling or water mist cooling is carried out to 150-200 DEG C, and then air cooling is carried out;

[0023] (6) spheroidizing annealing: annealing heating temperature 830±10℃, holding for 3-4 hours, cooling to 710±10℃ with furnace, holding for 4-6 hours, furnace cooling to ≤500℃, then out of furnace and air cooling, thus obtaining.

[0024] Further, the preparation method of the copper alloy continuous extrusion die material, wherein the smelting in step (1) is performed by using an electric arc furnace or a medium frequency furnace.

[0025] Further, the preparation method of the copper alloy continuous extrusion die material, wherein the forging in step (4) is performed by at least twice of upsetting on the electroslag ingot, the upsetting temperature is ≥1000℃, the first upsetting ratio is ≥2, and the total forging ratio is ≥12.

[0026] After the spheroidizing annealing of the forged material, the core is sampled and quenched, the sample size is 15mm*15mm*60mm, the heating temperature is 1090±10℃, the holding time is 1 hour, oil quenching to room temperature; the tempering temperature is 620±10℃, the tempering time is 2 hours each time, the sample is quenched twice, and the sample is cooled to room temperature after each tempering. After the quenching and tempering, the die steel has a tempering hardness of 50-52HRC; the standard V-notch Charpy impact sample with a size of 10mm*10mm*55mm is processed, and the transverse impact energy is ≥14J.

[0027] The beneficial effects of the present application are as follows:

[0028] The present application enhances the secondary hardening effect by Mo, W and Co alloying design, improves the high temperature strength, high temperature wear resistance and tempering stability of the die steel, and has high toughness, so that the impact energy of more than 14J can be achieved under the condition of tempering hardness of 50-52HRC, which meets the requirements of high temperature, high pressure and high wear resistance of the copper alloy extrusion die. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0030] Fig. 1 The metallographic picture of the annealing structure of the present application example 1 (transverse sample) is shown in the figure.

[0031] Fig. 2 The SEM picture of the annealing structure of the present application example 1 (transverse sample) is shown in the figure.

[0032] Fig. 3 The metallographic picture of the annealing structure of the present application example 1 (transverse sample) is shown in the figure. DETAILED DESCRIPTION

[0033] The present application will be further described in detail below in combination with the drawings and specific embodiments. Example 1

[0034] The preparation method of the copper alloy continuous extrusion die material of the embodiment comprises the following steps:

[0035] (1) Melting: ingredients are melted by an electric arc furnace, and then subjected to secondary refining outside the furnace, vacuum degassing, and casting into an electrode bar. The chemical composition of the electrode bar has a mass percentage of C: 0.47%, Si: 0.32%, Mn: 0.42%, Cr: 3.61%, Mo: 2.15%, V: 0.55%, W: 0.31%, Co: 0.39%, B: 0.0025%, P: 0.015%, S: 0.0038%, and the balance of Fe and inevitable impurities.

[0036] (2) Electroslag remelting: the electrode bar is subjected to shot blasting, and then electroslag remelting is performed to prepare an electroslag ingot with a diameter of 640 mm. The electroslag ingot is subjected to stress relief annealing at a heating temperature of 700°C and a holding time of 4h.

[0037] (3) High-temperature homogenization: the electroslag ingot is subjected to high-temperature homogenization treatment at a heating temperature of 1250°C and a holding time of 20h, and then is furnace-cooled to a forging temperature of 1180°C.

[0038] (4) Forging: the electroslag ingot is subjected to forging processing by adopting a two-piercing two-drawing + one-time reversing forging method. The forging heating temperature is 1180°C, the initial forging temperature is 1140°C, the final forging temperature is 850°C, the forging blank is a φ260mm rod, and after forging, air cooling is performed to 150-200°C, and then the blank is put into a slow cooling pit to be cooled to ≤100°C. The piercing temperature is ≥1000°C, the first piercing ratio is ≥2, the single-direction lengthening ratio is 6, and the total forging ratio is ≥12.

[0039] (5) Super-fining treatment: the obtained forged material is subjected to super-fining treatment. The normalizing heating temperature is 1110°C, the holding time is 2.5h, air cooling is performed to 150-200°C, and then air cooling is performed.

[0040] (6) Spheroidizing annealing: the annealing heating temperature is 830°C, the holding time is 3h, the blank is cooled to 700°C in the furnace, the holding time is 5h, the blank is furnace-cooled to 480°C, and then air cooling is performed after being taken out of the furnace, and the spheroidizing annealing is completed.

[0041] After the spheroidizing annealing, the forged material is sampled from the center, and then is subjected to quenching and tempering treatment. The sample size is 15mm×15mm×60mm, the heating temperature is 1080°C, the holding time is 1h, and oil quenching is performed to room temperature. The tempering temperature is 630°C, each tempering time is 2h, the sample is cooled to room temperature after each tempering, and the sample is subjected to secondary tempering.

[0042] After the quenching and tempering treatment, the die material has a tempering hardness of 50.1HRC. The die material is processed into a standard V-notch Charpy impact sample with a size of 10mm×10mm×55mm, and the transverse impact energy is 15.4J.

[0043] The annealing metallographic photograph (transverse sample) of the copper alloy continuous extrusion die material provided in the embodiment is as shown inFig. 1 annealed structure SEM (transverse sample) as shown in Figure 5, and the annealed banded segregation metallograph (longitudinal sample) as shown in Figure 6. Fig. 2 annealed structure SEM (transverse sample) as shown in Figure 5, and the annealed banded segregation metallograph (longitudinal sample) as shown in Figure 6. Fig. 3 It can be seen that the copper alloy continuous extrusion die material of the embodiment has a banded segregation SA1 level and an annealed structure AS2 level, and the carbides are dispersedly distributed and the uniformity of the structure is high. Figs. 1-3 It can be seen that the copper alloy continuous extrusion die material of the embodiment has a banded segregation SA1 level and an annealed structure AS2 level, and the carbides are dispersedly distributed and the uniformity of the structure is high. Example 2

[0044] The preparation method of the copper alloy continuous extrusion die material of the embodiment includes the following steps:

[0045] (1) Melting: The ingredients are melted by using an electric arc furnace, and then subjected to external refining, vacuum degassing, and cast into an electrode bar. The chemical composition of the electrode bar has a mass percentage of C: 0.49%, Si: 0.38%, Mn: 0.31%, Cr: 3.85%, Mo: 1.96%, V: 0.48%, W: 0.22%, Co: 0.33%, B: 0.0038%, P: 0.014%, S: 0.0042%, and the balance of Fe and inevitable impurities.

[0046] (2) Electroslag remelting: The surface of the electrode bar is ground and then subjected to electroslag remelting to prepare a φ640mm electroslag ingot. The obtained electroslag ingot is subjected to stress relief annealing at a heating temperature of 720℃ for 3h;

[0047] (3) High-temperature homogenization: The electroslag ingot is subjected to high-temperature homogenization treatment at a heating temperature of 1260℃ for 16h, and then furnace-cooled to a forging temperature of 1180℃;

[0048] (4) Forging: The electroslag ingot is subjected to forging processing by using a three-die three-drawing forging method. The forging heating temperature is 1180℃, the initial forging temperature is 1130℃, the final forging temperature is 820℃, the forging blank is a φ280mm rod, and after forging, air cooling is performed to 150-200℃, and then the blank is placed in a slow cooling pit to ≤100℃. The temperature for roughing is ≥1000℃, the first roughing ratio is ≥2, the single-direction elongation ratio is 5.2, and the total forging ratio is ≥12.

[0049] (5) Super-fining treatment: The obtained forged material is subjected to super-fining treatment. The normalizing heating temperature is 1100℃, the holding time is 3h, air cooling is performed to 150-200℃, and then air cooling is performed.

[0050] (6) Spheroidizing annealing: The annealing heating temperature is 820℃, the holding time is 4h, the blank is furnace-cooled to 710℃, the holding time is 6h, the blank is furnace-cooled to 480℃, and then air cooling is performed after being taken out of the furnace. Thus, the copper alloy continuous extrusion die material is obtained.

[0051] The core of the forged material after spheroidizing annealing is sampled and then quenched, the sample size is 15mmx15mmx60mm, the heating temperature is 1090℃, the holding time is 1 hour, the oil quenching is to room temperature; the tempering temperature is 620℃, the tempering time is 2 hours each time, the sample is cooled to room temperature after each tempering.

[0052] After the quenching and tempering treatment, the tempering hardness of the die material is 50.9HRC; the standard V-notch Charpy impact sample of 10mmx10mmx55mm is processed, the transverse impact energy is 15.1J. Example 3

[0053] The preparation method of the copper alloy continuous extrusion die material in the embodiment comprises the following steps:

[0054] (1) Melting: the ingredients are melted by using an electric arc furnace, and then subjected to external refining, vacuum degassing, and cast into an electrode rod, the chemical composition of the electrode rod has a mass percentage of C: 0.51%, Si: 0.42%, Mn: 0.48%, Cr: 3.89%, Mo: 2.05%, V: 0.40%, W: 0.28%, Co: 0.26%, B: 0.0042%, P: 0.014%, S: 0.0040%, and the balance of Fe and inevitable impurities.

[0055] (2) Electroslag remelting: the electrode rod is subjected to surface grinding treatment, and then electroslag remelting is performed to prepare a φ640mm electroslag ingot, and the obtained electroslag ingot is subjected to stress relief annealing, the heating temperature is 750℃, and the holding time is 2h;

[0056] (3) High-temperature homogenization: the electroslag ingot is subjected to high-temperature homogenization treatment, the heating temperature is 1240℃, and the holding time is 22 hours, and then the temperature is cooled to the forging temperature of 1170℃ in the furnace;

[0057] (4) Forging: the electroslag ingot is forged by using a three-die three-drawing forging method, the forging heating temperature is 1170℃, the initial forging temperature is 1130℃, the final forging temperature is 830℃, the forging blank is a φ250mm rod, the air cooling temperature after forging is 150-200℃, the sand burying temperature is ≤100℃, the upsetting temperature is ≥1000℃, the first upsetting ratio is ≥2, the single-direction lengthening ratio is 6.5, and the total forging ratio is ≥12;

[0058] (5) Super-fining treatment: the obtained forged material is subjected to super-fining treatment, the normalizing heating temperature is 1120℃, the holding time is 2 hours, the water mist cooling temperature is 150-200℃, and the air cooling is performed;

[0059] (6) Spheroidizing annealing: the annealing heating temperature is 840℃, the holding time is 3 hours, the temperature is cooled to 720℃ in the furnace, the holding time is 5 hours, the temperature is cooled to 490℃ in the furnace, and then the sample is taken out and air cooled, and the spheroidizing annealing is completed.

[0060] The core of the forged material after spheroidizing annealing is sampled and then tempered, the sample size is 15mmx15mmx60mm, the heating temperature is 1100℃, the holding time is 1 hour, and the oil quenching is performed to room temperature; the tempering temperature is 620℃, the tempering time is 2 hours each time, the sample is cooled to room temperature after each tempering, and the sample is tempered twice.

[0061] After the tempering treatment, the tempering hardness of the die material is 51.8HRC; the standard V-notch Charpy impact sample with a size of 10mmx10mmx55mm is processed, and the transverse impact energy is 14.5J. Example 4

[0062] The preparation method of the copper alloy continuous extrusion die material in the embodiment comprises the following steps:

[0063] (1) Melting: the ingredients are melted by using a medium frequency furnace, and then subjected to external refining and vacuum degassing, and cast into an electrode rod, the chemical composition of the electrode rod has a mass percentage of C: 0.50%, Si: 0.48%, Mn: 0.50%, Cr: 3.67%, Mo: 1.85%, V: 0.58%, W: 0.35%, Co: 0.30%, B: 0.0031%, P: 0.017%, S: 0.0045%, and the balance is Fe and inevitable impurities.

[0064] (2) Electroslag remelting: the electrode rod is subjected to surface grinding treatment, and then subjected to electroslag remelting to prepare an electroslag ingot with a diameter of 640mm, and the obtained electroslag ingot is subjected to stress relief annealing, the heating temperature is 730℃, and the holding time is 3 hours;

[0065] (3) High-temperature homogenization: the electroslag ingot is subjected to high-temperature homogenization treatment, the heating temperature is 1250℃, and the holding time is 20 hours, and then the furnace is cooled to a forging temperature of 1160℃;

[0066] (4) Forging: the electroslag ingot is forged by using a three-die three-drawing forging method, the forging heating temperature is 1160℃, the initial forging temperature is 1120℃, the final forging temperature is 820℃, the forged blank is a 220mm diameter rod, the air cooling temperature after forging is 150-200℃, the sand burying temperature is ≤100℃, the roughing temperature is ≥1000℃, the first roughing ratio is ≥2, the single-direction lengthening ratio is 8.4, and the total forging ratio is ≥12;

[0067] (5) Super-fining treatment: the obtained forged material is subjected to super-fining treatment, the normalizing heating temperature is 1110℃, the holding time is 2.5 hours, the water mist cooling temperature is 150-200℃, and the air cooling is performed;

[0068] (6) Spheroidizing annealing: the annealing heating temperature is 840℃, the holding time is 4 hours, the furnace cooling is performed to 700℃, the holding time is 6 hours, the furnace cooling is performed to 460℃, and then the air cooling is performed after the furnace is discharged, and the spheroidizing annealing is completed.

[0069] The core of the forged material after spheroidizing annealing is sampled and then quenched, the sample size is 15mmx15mmx60mm, the heating temperature is 1080℃, the holding time is 1 hour, the oil quenching is to room temperature; the tempering temperature is 620℃, the tempering time is 2 hours each time, the sample is cooled to room temperature after each tempering.

[0070] After the quenching and tempering treatment, the mold material tempering hardness is 51.8HRC; the standard V-notch Charpy impact sample of 10mmx10mmx55mm is processed, the transverse impact energy is 14.5J. Example 5

[0071] The preparation method of the copper alloy continuous extrusion mold material in the embodiment comprises the following steps:

[0072] (1) Melting: the ingredients are melted by using a medium frequency furnace, and then subjected to external refining and vacuum degassing, and cast into an electrode bar, the chemical composition of the electrode bar has the mass percentage of C: 0.48%, Si: 0.50%, Mn: 0.36%, Cr: 3.98%, Mo: 1.82%, V: 0.50%, W: 0.38%, Co: 0.21%, B: 0.0048%, P: 0.020%, S: 0.0039%, and the balance of Fe and inevitable impurities.

[0073] (2) Electroslag remelting: the electrode bar is subjected to shot blasting treatment, and then subjected to electroslag remelting to prepare an electroslag ingot with a diameter of 640mm, and the obtained electroslag ingot is subjected to stress relief annealing, the heating temperature is 720℃, and the holding time is 4 hours;

[0074] (3) High-temperature homogenization: the electroslag ingot is subjected to high-temperature homogenization treatment, the heating temperature is 1260℃, and the holding time is 16 hours, and then the temperature is cooled to the forging temperature of 1170℃ in the furnace;

[0075] (4) Forging: the electroslag ingot is forged by adopting the two-pier two-drawing + one-time reversing forging mode, the forging heating temperature is 1170℃, the initial forging temperature is 1110℃, the final forging temperature is 820℃, the forging blank is a 240mm diameter rod, the temperature is air-cooled to 150-200℃ after forging, and buried sand to ≤100℃; the pier roughening temperature is ≥1000℃, the first pier roughening ratio is ≥2, the single-direction lengthening ratio is 7.1, and the total forging ratio is ≥12;

[0076] (5) Super-fining treatment: the obtained forged material is subjected to super-fining treatment, the normalizing heating temperature is 1120℃, the holding time is 2 hours, the water mist cooling is to 150-200℃, and the air cooling is performed;

[0077] (6) Spheroidizing annealing: the annealing heating temperature is 820℃, the holding time is 3 hours, the temperature is cooled to 720℃ in the furnace, the holding time is 6 hours, the temperature is cooled to 470℃ in the furnace, and then the sample is air-cooled after being taken out of the furnace, and the spheroidizing annealing is completed.

[0078] The core of the forged material after spheroidizing annealing is sampled and then quenched, the sample size is 15mmx15mmx60mm, the heating temperature is 1090℃, the holding time is 1 hour, the oil quenching is to room temperature; the tempering temperature is 630℃, the tempering time is 2 hours each time, the sample is cooled to room temperature after each tempering.

[0079] After the quenching and tempering treatment, the mold material tempering hardness is 50.3HRC; the standard V-notch Charpy impact sample of 10mmx10mmx55mm is processed, the transverse impact energy is 15.8J. Example 6

[0080] The preparation method of the copper alloy continuous extrusion mold material in the embodiment comprises the following steps:

[0081] (1) Melting: the ingredients are melted by using a medium frequency furnace, and then subjected to external refining and vacuum degassing, and cast into an electrode bar, the chemical composition of the electrode bar has the mass percentage of C: 0.47%, Si: 0.30%, Mn: 0.44%, Cr: 3.73%, Mo: 1.90%, V: 0.51%, W: 0.23%, Co: 0.35%, B: 0.0026%, P: 0.018%, S: 0.0053%, and the balance of Fe and inevitable impurities.

[0082] (2) Electroslag remelting: the electrode bar is subjected to shot blasting treatment, and then subjected to electroslag remelting to prepare an electroslag ingot with a diameter of 640mm, and the obtained electroslag ingot is subjected to stress relief annealing, the heating temperature is 750℃, and the holding time is 3 hours;

[0083] (3) High-temperature homogenization: the electroslag ingot is subjected to high-temperature homogenization treatment, the heating temperature is 1240℃, and the holding time is 22 hours, and then the temperature is cooled to the forging temperature of 1160℃ in the furnace;

[0084] (4) Forging: the electroslag ingot is subjected to forging processing by adopting the two-pier two-drawing + one-time reversing forging mode, the forging heating temperature is 1160℃, the initial forging temperature is 1100℃, the final forging temperature is 840℃, the forging blank is a φ230mm rod, the temperature is air-cooled to 150-200℃ after forging, and then the temperature is cooled to ≤100℃ in the slow cooling pit; the pier roughening temperature is ≥1000℃, the first pier roughening ratio is ≥2, the single-direction lengthening ratio is 7.7, and the total forging ratio is ≥12;

[0085] (5) Super-fining treatment: the obtained forged material is subjected to super-fining treatment, the normalizing heating temperature is 1110℃, the holding time is 3 hours, the temperature is air-cooled to 150-200℃, and then the temperature is air-cooled.

[0086] (6) Spheroidizing annealing: the annealing heating temperature is 840℃, the holding time is 2 hours, the temperature is cooled to 700℃ in the furnace, the holding time is 5 hours, the temperature is cooled to 490℃ in the furnace, and then the temperature is air-cooled after being taken out of the furnace, and the spheroidizing annealing is completed.

[0087] The sample of the center of the forged material after spheroidizing annealing was tempered, the sample size was 15 mm x 15 mm x 60 mm, the heating temperature was 1100 DEG C, the holding time was 1 hour, the oil quenching was to room temperature; the tempering temperature was 610 DEG C, the tempering time was 2 hours each time, the tempering was twice, and the sample was cooled to room temperature after each tempering.

[0088] After the tempering treatment, the die material tempering hardness was 51.9 HRC; the standard V notch charpy impact sample with 10 mm x 10 mm x 55 mm was processed, and the transverse impact energy was 14.2 J.

Claims

1. A copper alloy continuous extrusion die material characterized by, The chemical composition and mass percentage of the extrusion die material are as follows: C: 0.47-0.51%, Si: 0.30-0.50%, Mn: 0.30-0.50%, Cr: 3.60-4.00%, Mo: 1.80-2.20%, V: 0.40-0.60%, W: 0.20-0.40%, Co: 0.20-0.40%, B: 0.002-0.005%, P≤0.020%, S≤0.010%, and the balance of Fe and inevitable impurities; The tempering hardness of the extrusion die material after quenching and tempering treatment is 50-52 HRC, and the transverse impact energy is ≥14 J.

2. The method of producing a continuous extrusion die material for copper alloys according to claim 1, characterized by, The preparation method comprises the following steps: (1) smelting: smelting the ingredients, and then performing external refining, vacuum degassing, and casting into an electrode bar; (2) electroslag remelting: performing surface grinding or shot blasting treatment on the electrode bar, and then performing electroslag remelting to obtain an electroslag ingot, which is stress relieved at a heating temperature of 700-750 °C for 2-4 h; (3) high-temperature homogenization: performing high-temperature homogenization treatment on the electroslag ingot at a heating temperature of 1240-1260 °C for (0.25-0.35) × D hours (D is the diameter of the electroslag ingot in cm), and then furnace cooling to a forging temperature of 1160-1180 °C; (4) forging: initial forging temperature of 1100-1140 °C, final forging temperature of 820-850 °C, air cooling to 150-200 °C after forging, and entering a slow cooling pit or sand embedding slow cooling; (5) superfine treatment: performing superfine treatment on the obtained forged material, normalizing heating temperature of 1100-1120 °C, heat preservation for 2-3 hours, air cooling or water mist cooling to 150-200 °C, and air cooling; (6) spheroidizing annealing: annealing heating temperature of 830±10 °C, heat preservation for 3-4 hours, furnace cooling to 710±10 °C, heat preservation for 4-6 hours, furnace cooling to ≤500 °C, and then air cooling after exiting the furnace.

3. The method of producing a copper alloy continuous extrusion die material according to claim 2, characterized by, The smelting in step (1) is performed by using an electric arc furnace or a medium-frequency furnace.

4. The method of producing a copper alloy continuous extrusion die material according to claim 2, characterized by, The forging in step (4) is performed by using at least two times of upsetting on the electroslag ingot, and the upsetting temperature is ≥1000 °C, the first upsetting ratio is ≥2, and the total forging ratio is ≥12.

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