High-temperature alloy for copper-nickel alloy hot extrusion die and preparation method of high-temperature alloy

Abstract

The invention provides a high-temperature alloy for manufacturing a nickel-copper alloy hot extrusion die, which is characterized by comprising the following components in percentage by weight: 0.02 to 0.08 percent of C, less than or equal to 0.15 percent of Si, less than or equal to 0.15 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of S, 14.0 to 17.0 percent of Cr, 7.5 to 9.5 percent of Mo, 2.2 to 2.6 percent of Nb, 1.0 to 1.6 percent of Al, 2.2 to 2.8 percent of Ti, 0.005 to 0.015 percent of B, 0.01 to 0.05 percent of Zr, 21.0 to 24.0 percent of Fe and the balance of Ni. The preparation method of the alloy comprises the following processes: firstly, alloy raw materials are subjected to vacuum induction melting and then cast into ingots, then electroslag ingots are obtained through electroslag remelting, then the electroslag ingots are subjected to multi-heating-number forging, and then heat treatment is carried out. The highest use temperature of the alloy reaches 1000 DEG C, and the oxidation rate at 1000 DEG C is as low as 0.08 g / m < 2 >. H; at the temperature of 650 DEG C, the tensile strength reaches 1000 MPa, the yield strength reaches 850 MPa, the fatigue strength is higher than 400 MPa, and the lasting time of the load of 700 MPa reaches 80 h; the service life of a nickel-copper alloy hot extrusion die made of the alloy can reach 25000 times.

Description

Technical Field

[0001] The invention relates to the field of special alloy materials, and in particular to a high-temperature alloy for making a nickel-copper alloy hot extrusion die and a preparation method thereof. Background Art

[0002] Nickel-copper alloy is an important alloy material widely used in shipbuilding, petrochemical, electrical appliances, instruments, medical equipment, daily necessities, handicrafts and other fields. Hot extrusion dies are required in the hot extrusion process of nickel-copper alloy processing and forming. Hot extrusion is to heat the nickel-copper ingot or nickel-copper billet to a certain temperature and then extrude it through a die under high pressure. The heating temperature of hot extrusion of nickel-copper alloy is generally 870-1000℃. Such extremely high temperature places high demands on the high temperature strength, oxidation resistance, fatigue strength and wear resistance of the mold material.

[0003] At present, nickel-copper alloy hot extrusion dies are usually made of 4Cr5MoSiV1, 3Cr2W8V, and W6Mo5Cr4V2 materials. However, these materials still have some shortcomings: 4Cr5MoSiV1 is used for nickel-copper alloy hot extrusion dies, and has the following disadvantages: 1) Low fatigue strength and short service life. 2) Insufficient high temperature strength above 650℃. 3) Insufficient oxidation resistance above 650℃. 4) Insufficient endurance life at hot extrusion temperatures of 870-1000℃. 3Cr2W8V is used for nickel-copper alloy hot extrusion dies, and has the following disadvantages: 1) Poor anti-adhesive wear performance and poor surface quality of nickel-copper workpieces. 2) Severe carbide segregation and poor uniformity of die hardness. 3) Poor plasticity, toughness, and impact performance. 4) When subjected to impact loads, the die is prone to cracks and failure. 5) Poor thermal conductivity. 6) Poor thermal fatigue resistance and anti-corrosion performance. W6Mo5Cr4V2 is used in nickel-copper alloy hot extrusion dies, which has the following disadvantages: 1) The die heat treatment process is complicated and the heat treatment cost is high. 2) The high temperature strength above 650℃ is insufficient. 3) The plasticity, toughness and impact properties are poor. 4) It is easy to oxidize and decarburize at high temperature, and the die maintenance frequency is high, and the die maintenance cost is high.

[0004] In view of the defects of the current nickel-copper alloy hot extrusion die materials, there is a need to develop a new nickel-copper alloy hot extrusion die material to meet the requirements of the latest technology, latest equipment, and latest process for hot extrusion of nickel-copper alloys. Summary of the invention

[0005] In order to solve the above problems, the present invention aims to provide a high-temperature alloy for copper-nickel alloy hot extrusion dies, which can achieve a long-term use temperature of up to 900-1000°C, has higher high-temperature strength, better high-temperature durability, higher fatigue strength, better oxidation resistance and longer service life, and a preparation method thereof.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The invention provides a high-temperature alloy for making a nickel-copper alloy hot extrusion die, characterized in that the alloy comprises the following components by weight percentage: C 0.02-0.08%, Si≤0.15%, Mn≤0.15%, P≤0.01%, S≤0.01%, Cr 14.0-17.0%, Mo 7.5-9.5%, Nb 2.2-2.6%, Al 1.0-1.6%, Ti 2.2-2.8%, B 0.005-0.015%, Zr 0.01-0.05%, Fe 21.0-24.0%, and Ni as the balance. The maximum use temperature of the alloy reaches 1000°C, and the oxidation rate at 1000°C is as low as 0.08g / m 2 h; at 650℃, the tensile strength reaches 1000MPa, the yield strength reaches 850MPa, the fatigue strength is higher than 400MPa, and the endurance time under a load of 700MPa reaches 80h; the grain size grade is 8; the alloy is made into a nickel-copper alloy hot extrusion die with a service life of 25,000 times.

[0008] The present invention also provides a method for preparing the above-mentioned high-temperature alloy for copper-nickel alloy hot extrusion die, which is characterized in that the alloy raw material is firstly cast into an ingot by vacuum induction melting, then electroslag remelting is performed to obtain an electroslag ingot, and then the electroslag ingot is subjected to multi-fire forging and then heat treatment.

[0009] Furthermore, in the method for preparing the high temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, it can also have the following characteristics: wherein the vacuum induction melting includes the following process:

[0010] 1) Loading;

[0011] 2) Vacuuming:

[0012] Turn on the mechanical pump to draw a vacuum, the power supply is 50-70KW;

[0013] When the vacuum degree is ≤1000Pa, turn on the Roots pump to evacuate the vacuum;

[0014] When the vacuum degree is ≤1Pa, the power is increased to 120-150KW;

[0015] When the vacuum degree is ≤1Pa, open the high vacuum valve;

[0016] 3) Melting:

[0017] The vacuum degree during the melting period is ≤1Pa, and the vacuum degree is maintained at ≤0.067Pa during the melting period. After melting, the temperature is measured and samples are taken;

[0018] 4) Refining:

[0019] The vacuum degree during the refining period is ≤1Pa, the refining temperature is controlled at 1620~1660℃, the refining time is ≥30 minutes, and after the refining, the temperature is measured and samples are taken to prepare for furnace reversal and steel tapping;

[0020] 5) Casting:

[0021] Stir for 3-5 minutes before tapping, then cast the steel to obtain a steel ingot.

[0022] Furthermore, in the preparation method of the high-temperature alloy for copper-nickel alloy hot extrusion die provided by the present invention, it can also have the following characteristics: wherein, Mn in the alloy is provided by raw material electrolytic manganese, Ti is provided by raw material pure titanium, B is provided by raw material ferroboron, and Zr is provided by raw material metal zirconium; electrolytic manganese and pure titanium are added after refining for 10-20 minutes during the refining period; ferroboron and metal zirconium are added 5 minutes before steelmaking.

[0023] Furthermore, in the method for preparing the high-temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, the method may also have the following characteristics: wherein the electroslag remelting includes the following process:

[0024] 1) Arcing and slag-melting stage: the current is gradually increased from 1500A to 5000A, and the slag-melting time is not less than 40 minutes;

[0025] 2) Current increase stage: the current gradually increases from 5000A to 8000A, which takes 25 minutes;

[0026] 3) Melting stage: the voltage is stable, and the electrode is remelted using a constant current of 7500-8000A;

[0027] 4) Feeding stage: gradually reduce the voltage and current, the current gradually drops to 2000A, and the feeding time is not less than 30 minutes.

[0028] Furthermore, in the preparation method of the high-temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, it can also have the following characteristics: wherein, the arcing and slag forming stage includes the following current gradually increasing process: current 1500A, maintained for at least 5 minutes; current 2000A, maintained for at least 5 minutes; current 2500A, maintained for at least 5 minutes; current 3000A, maintained for at least 5 minutes; current 3500A, maintained for at least 5 minutes; current 4000A, maintained for at least 5 minutes; current 4500A, maintained for at least 5 minutes; current 5000A, maintained for at least 5 minutes.

[0029] Furthermore, in the preparation method of the high-temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, it can also have the following characteristics: wherein, the current rising stage includes the following current gradually increasing process: current 5500A, maintained for 5 minutes; current 6000A, maintained for 5 minutes; current 6500A, maintained for 5 minutes; current 7000A, maintained for 5 minutes; current 7500A, maintained for 5 minutes.

[0030] Furthermore, in the method for preparing the high temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, it can also have the following characteristics: wherein the multi-fire forging includes the following process:

[0031] 1) Continuously raise the temperature to 600°C and keep it for 1 hour;

[0032] 2) Continuously raise the temperature to 800°C and keep it for 1 hour;

[0033] 3) Continuously raise the temperature to the soaking temperature and start forging, keep warm for 1 to 4 hours, and the soaking temperature is a constant temperature of 1100 to 1200°C;

[0034] 4) Final forging temperature ≥930℃.

[0035] Furthermore, in the preparation method of the high-temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, it can also have the following characteristics: when the electroslag ingot is 0.5 tons, the insulation time is 1 to 3 hours; when the electroslag ingot is 1 ton, the insulation time is 3 to 4 hours.

[0036] Furthermore, in the method for preparing the high-temperature alloy for the copper-nickel alloy hot extrusion die provided by the present invention, the following features may be provided: wherein the heat treatment includes the following processes:

[0037] 1) Solution: Solution temperature is 1000-1060℃, holding time is T minutes, T=1.2D, where D represents the outer diameter of the forging material, the unit is mm, T is not less than 60 minutes and not more than 120 minutes; after the holding is completed, it is taken out of the furnace and water-cooled;

[0038] 2) Aging: Aging temperature is 710-730°C, and the temperature is kept for 8-10 hours; then, the furnace is cooled to 610-630°C, and the temperature is kept for 8-10 hours; then, air-cooled to room temperature.

[0039] Function and effect of the present invention:

[0040] The high-temperature alloy for hot extrusion die of nickel-copper alloy of the present invention is a nickel-based high-temperature alloy, which adopts a specific optimized composition scheme: C 0.02-0.08%, Si≤0.15%, Mn≤0.15%, P≤0.01%, S≤0.01%, Cr 14.0-17.0%, Mo 7.5-9.5%, Nb 2.2-2.6%, Al 1.0-1.6%, Ti 2.2-2.8%, B 0.005-0.015%, Zr 0.01-0.05%, Fe 21.0~24.0%, chromium, nickel, molybdenum, niobium, titanium, aluminum, boron, zirconium and other elements are combined to improve the alloy's strength, hardness, organizational stability, oxidation resistance, corrosion resistance and thermal stability; its smelting process is a combination of vacuum induction melting and electroslag remelting, which can produce electroslag ingots with uniform composition, small segregation, higher purity, lower inclusions and better surface quality; its multi-fire forging process obtains fine grains, and forgings with excellent room temperature mechanical properties, high temperature mechanical properties, endurance performance, fatigue performance and oxidation resistance; its specific heat treatment process can precipitate More strengthening phases such as Ni3Al, Ni3Ti, Ni3(Al, Ti) etc. inhibit the precipitation of brittle phases such as α, σ, Laves etc., further improve the high temperature strength of the alloy, improve the endurance strength, and refine the alloy grains; the high temperature alloy of the present invention is used to manufacture nickel-copper alloy hot extrusion dies, and its long-term use temperature is as high as 900-1000°C, and it has higher high temperature strength, better high temperature endurance performance, higher fatigue strength, better oxidation resistance, and longer service life, which fully meets the use requirements of the latest technology, latest equipment, and latest process for hot extrusion of nickel-copper alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a diagram of the electroslag remelting current system for preparing a high-temperature alloy for a copper-nickel alloy hot extrusion die according to an embodiment of the present invention;

[0042] Figure 2 It is a forging heating process curve diagram of the copper-nickel alloy hot extrusion die prepared with a high-temperature alloy according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following embodiments are combined with the accompanying drawings to specifically illustrate the technical solutions of the present invention.

[0044] <Example>

[0045] In an embodiment of the present invention, a high-temperature alloy for a copper-nickel alloy hot extrusion die is provided, which includes the following components in weight percentage: C 0.02-0.08%, Si≤0.15%, Mn≤0.15%, P≤0.01%, S≤0.01%, Cr 14.0-17.0%, Mo7.5-9.5%, Nb2.2-2.6%, Al 1.0-1.6%, Ti2.2-2.8%, B 0.005-0.015%, Zr0.01-0.05%, Fe21.0-24.0%, and Ni is the balance.

[0046] Table 1 shows the composition of the high temperature alloy for the copper-nickel alloy hot extrusion die of the preferred embodiment:

[0047] element C Si Mn P S Cr Mo Nb Al Ti B Zr Fe Label 1 0.04 0.10 0.10 0.008 0.001 15.0 8.0 2.4 1.3 2.5 0.008 0.02 22.5 Label 2 0.04 0.10 0.10 0.008 0.001 15.5 8.0 2.4 1.3 2.5 0.008 0.02 22.5 Label 3 0.04 0.10 0.10 0.008 0.001 16.0 8.0 2.4 1.3 2.5 0.008 0.02 22.5 Label 4 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.5 0.008 0.02 22.5 Number 5 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.5 0.008 0.02 22.5 Number 6 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.3 1.3 2.5 0.008 0.02 22.5 Number 7 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.5 1.3 2.5 0.008 0.02 22.5 Number 8 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.1 2.5 0.008 0.02 22.5 Number 9 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.5 2.5 0.008 0.02 22.5 No. 10 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.4 0.008 0.02 22.5 No. 11 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.6 0.008 0.02 22.5 No. 12 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.5 0.010 0.02 22.5 No. 13 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.5 0.012 0.02 22.5 No. 14 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.5 0.010 0.03 22.5 No. 15 0.04 0.10 0.10 0.008 0.001 15.5 8.5 2.4 1.3 2.5 0.010 0.04 22.5

[0048] The solution numbered 14 in the above Table 1 is the optimal component solution.

[0049] The copper-nickel alloy hot extrusion die high temperature alloy is prepared according to the following method:

[0050] 1. Raw material preparation

[0051] Select low-carbon, low-phosphorus, and low-sulfur alloy raw materials, including micro-carbon ferrochrome (or metallic chromium), ferromolybdenum (or molybdenum bars), niobium bars, electrolytic nickel, pure aluminum, pure titanium, pure iron, crystalline silicon, electrolytic manganese, carbon powder (or carbon block), ferroboron, and metallic zirconium. You can also use the returned materials of this steel grade appropriately. Keep the raw materials dry, clean, oil-free, dirt-free, and rust-free. If the raw materials are damp, dry the moisture before use.

[0052] 2. Vacuum induction melting

[0053] 1) Loading:

[0054] First, load the main raw materials into the vacuum induction furnace. Before loading the large materials, lay a layer of fine and light materials on the bottom of the furnace. The materials should be loose on the top and tight on the bottom to prevent "bridging".

[0055] The remaining raw materials, electrolytic manganese and pure titanium, are added after 10-20 minutes of refining in the subsequent refining process, while ferroboron and metallic zirconium are added 5 minutes before steelmaking.

[0056] 2) Vacuuming:

[0057] Turn on the mechanical pump to create a vacuum, with a power of 50-70KW, and record the water temperature and vacuum degree every 20 minutes.

[0058] Turn on the boost pump to increase the oil temperature.

[0059] When the vacuum degree is ≤1000Pa, turn on the Roots pump to evacuate.

[0060] When the vacuum degree is ≤1Pa, the power is increased to 120-150KW.

[0061] When the vacuum degree is ≤1Pa, open the high vacuum valve.

[0062] 3) Melting:

[0063] The vacuum degree during the melting period is ≤1Pa, and the vacuum degree during the melting period is maintained at ≤0.067Pa. After melting, measure the temperature and take samples.

[0064] 4) Refining:

[0065] The vacuum degree during the refining period is ≤1Pa, the refining temperature is controlled at 1620-1660℃, the refining time is ≥30 minutes, and after the refining is completed, the temperature is measured and samples are taken to prepare for the furnace to be turned over and steel is tapped.

[0066] The purpose of the refining period is to deoxidize, degas, adjust the elemental composition, adjust the temperature, etc.

[0067] After refining for 10-20 minutes, electrolytic manganese and pure titanium are added.

[0068] Before sampling, tilt the crucible back and forth to wash away splashes on the crucible wall, and then take samples for analysis to even out the composition of the molten steel. According to the analysis results of the molten sample composition, calculate the amount of each metal element to be added, weigh it and add it to the furnace. After 5 minutes of adding, shake the crucible and start electromagnetic stirring to even out the composition and temperature of the molten steel.

[0069] Ferroboron and metal zirconium are added 5 minutes before steel is tapped. Temperature is measured and samples are taken for analysis. When the temperature and composition meet the process requirements, the corresponding valves are closed, the pump is stopped, the maintenance pump and valve are opened, argon is flushed, and the furnace is turned over for steel tapping.

[0070] 5) Casting:

[0071] The steel is stirred for 3-5 minutes before tapping, and then cast to obtain a steel ingot. The melting point of the alloy of the present invention is about 1390-1410°C, the casting temperature is controlled at 1580-1600°C, and the steel ingot can be demoulded after cooling for more than 30 minutes.

[0072] 3. Electroslag remelting

[0073] The electrode specification used in the electroslag remelting process is Φ220mm, and the electroslag ingot shape is determined by production: it can be Φ320mm, Φ360 or Φ390mm. The slag volume is generally 4% of the electrode weight.

[0074] Before electroslag, the ingot plate (pure iron plate), starting plate (Bengang gasket), and arc starter (fluorite titanium dioxide) must be baked, and the baking temperature can be controlled at 200-250℃, and the baking time is more than 2 hours. Before electroslag, the electrode rod and protective slag must be baked, and the baking temperature can be controlled at 500-600℃, and the baking time is more than 6 hours.

[0075] Electroslag remelting includes the following processes:

[0076] 1) Arcing and slag-melting stage: The current is gradually increased from 1500A to 5000A, and the slag-melting time is not less than 40 minutes. When the crystallizer slag pool turns red and the slag fluidity is good, it can be regarded as the end of slag-melting.

[0077] The arcing and slagging stage includes the following process of gradual current increase:

[0078] Current 1500A, maintained for at least 5 minutes;

[0079] Current 2000A, maintained for at least 5 minutes;

[0080] Current 2500A, maintained for at least 5 minutes;

[0081] Current 3000A, maintained for at least 5 minutes;

[0082] Current 3500A, maintained for at least 5 minutes;

[0083] Current 4000A, maintained for at least 5 minutes;

[0084] Current 4500A, maintained for at least 5 minutes;

[0085] The current is 5000A and maintained for at least 5 minutes.

[0086] See also Figure 1 In the embodiment of the present invention, the arcing and slag forming stage is 40 minutes, including 8 current gradients, and each current value is maintained for 5 minutes.

[0087] 2) Current increase stage: the current gradually increases from 5000A to 8000A, which takes 25 minutes;

[0088] The current rising stage includes the following current gradually rising process:

[0089] Current 5500A, maintain for 5 minutes;

[0090] Current 6000A, maintain for 5 minutes;

[0091] Current 6500A, maintain for 5 minutes;

[0092] Current 7000A, maintain for 5 minutes;

[0093] Current 7500A, maintain for 5 minutes.

[0094] 3) Melting stage: The voltage is stable and a constant current is used to remelt the electrode. The constant current is 7500-8000A.

[0095] 4) Feeding stage: gradually reduce the voltage and current, the current gradually drops to 2000A, and the feeding time is not less than 30 minutes.

[0096] See also Figure 1 In the embodiment of the present invention, the feeding time of the feeding stage is 30 minutes.

[0097] 5) Mold cooling:

[0098] The cooling time of Φ320 and Φ360 steel ingot molds is ≥40 minutes, and the cooling time of Φ390 steel ingot mold is ≥50 minutes.

[0099] 4. Forging

[0100] Use multiple forging passes, and the deformation of a single pass does not exceed 50% to prevent cracks caused by excessive deformation. Figure 2 , multi-fire forging includes the following processes:

[0101] 1) Continuously raise the temperature to 600°C and keep it for 1 hour.

[0102] 2) Continuously increase the temperature to 800°C and keep it at this temperature for 1 hour.

[0103] 3) Continuously raise the temperature to the absorptive temperature and start forging. Keep the temperature for 1 to 4 hours. The absorptive temperature should be a constant temperature of 1100 to 1200°C.

[0104] 4) Continuously cool down for final forging, the final forging temperature is ≥930℃.

[0105] When the weight of the electroslag ingot is 0.5 ton, the holding time is 1 to 3 hours. When the weight of the electroslag ingot is 0.5 ton, the preferred ingot soaking temperature is 1150°C, and the preferred ingot holding time is 2 hours.

[0106] When the electroslag ingot weighs 1 ton, the holding time is 3 to 4 hours. When the electroslag ingot weighs 1 ton, the preferred ingot soaking temperature is 1150°C, and the preferred ingot holding time is 3 hours.

[0107] The holding time of the intermediate billet in the furnace shall be ≥1h to ensure uniform and thorough burning and prevent yin and yang surfaces. The forging ratio shall be ≥4. The head and tail removal rate requirements of forging materials are: the head of the steel ingot shall be ≥3%, and the tail shall be ≥5%.

[0108] 5. Nondestructive testing

[0109] Forgings are subjected to ultrasonic testing in accordance with GB / T 4162-2022 “Ultrasonic Testing Methods for Forged Steel Bars”. Internal defects should be marked and removed.

[0110] 6. Heat treatment

[0111] 3) Solid solution:

[0112] The solution temperature is 1000-1060℃, the holding time is T minutes, T=1.2D, where D represents the outer diameter of the forging material, the unit is mm, T is not less than 60 minutes and not more than 120 minutes. After the holding is completed, it is taken out of the furnace and water-cooled.

[0113] Preferably, in the optimization scheme of solution heat treatment, the solution temperature is 1030° C. and the holding time is 1 hour.

[0114] 4) Time limit:

[0115] Aging temperature 710-730℃, keep warm for 8-10 hours;

[0116] Then, the furnace is cooled to 610-630°C and kept at this temperature for 8-10 hours;

[0117] Then, air cool to room temperature.

[0118] 7. Skinning

[0119] After solution treatment, the bar is peeled to remove surface defects such as oxide scale, folding, warping, slag inclusion, etc.

[0120] 8. Inspection, packaging and storage

[0121] <Comparative Example 1>

[0122] Comparative Example 1 is 4Cr5MoSiV1 alloy.

[0123] The alloy comprises the following components in weight percentage: C 0.32-0.45%, Si 0.8-1.2%, Mn 0.2-0.5%, P≤0.030%, S≤0.030%, Cr4.75-5.50%, Mo 1.10-1.75%, V0.80-1.20%, Ni≤0.25%, Cu≤0.30%, and Fe as the balance.

[0124] 4Cr5MoSiV1 alloy is usually prepared by the following method:

[0125] 1. Raw material preparation

[0126] Raw materials include scrap steel, ferrochrome, ferromolybdenum, ferrovanadium, ferrosilicon, ferromanganese, pure iron, etc.

[0127] 2. Electric arc furnace primary smelting

[0128] A steelmaking method that uses the thermal effect of electric arc to heat the charge for melting. Alternating current is input into the furnace through three graphite electrodes, and an arc is generated between the lower end of the electrode and the metal material. The high temperature of the arc is used to directly heat the charge, allowing the steelmaking process to proceed. Electric arc furnace steelmaking uses scrap steel as the main raw material. Depending on the furnace lining material and slag-making material, there are alkaline and acidic methods. The most commonly used is the alkaline method: electric arc furnace steelmaking uses electricity as a heat source, avoiding the pollution of steel by sulfur contained in the gas heat source; the operating process is flexible, and both the slag and furnace gas can be adjusted to oxidizing or reducing; strong reducing properties can cause precious elements such as chromium, nickel, tungsten, molybdenum, vanadium, and titanium contained in the charge to be rarely burned; the furnace temperature is high and easy to control; the product quality is high.

[0129] 3. Ladle furnace refining

[0130] LF furnace refining is one of the main methods of refining outside the furnace, which can quickly produce white slag. The purpose of LF slag making is to desulfurize, deoxidize, improve alloy yield and remove inclusions. The main functions of the ladle refining furnace include desulfurization, temperature control, alloying and removal of inclusions.

[0131] 4. Vacuum ladle furnace refining

[0132] Vacuum ladle furnace is a commonly used refining process equipment, mainly used to remove oxygen and impurities from molten steel, so as to obtain high-purity, low-impurity high-quality steel. The process flow of vacuum ladle furnace refining mainly includes: vacuum suction, dehydrogenation, temperature adjustment, refining, alloying, steel tapping, etc.

[0133] 5. Forging

[0134] The same process as that of the embodiment of the present invention may be employed.

[0135] 6. Nondestructive testing

[0136] The same process as that of the embodiment of the present invention may be employed.

[0137] 7. Heat treatment

[0138] The same process as that of the embodiment of the present invention may be employed.

[0139] 8. Skinning

[0140] The same process as that of the embodiment of the present invention may be employed.

[0141] 9. Inspection, packaging and storage

[0142] The same process as that of the embodiment of the present invention may be employed.

[0143] <Comparative Example 2>

[0144] Comparative Example 2 is 3Cr2W8V alloy.

[0145] The alloy comprises the following components in weight percentage: C 0.30-0.40%, Si≤0.4%, Mn≤0.4%, P≤0.030%, S≤0.030%, Cr 2.2-2.7%, W 7.5-9.0%, V 0.20-0.50%, and Fe as the balance.

[0146] 3Cr2W8V alloy is usually prepared by the following method:

[0147] 1. Raw material preparation

[0148] Raw materials include scrap steel, ferrotungsten, ferrochrome, ferrovanadium, ferrosilicon, ferromanganese, pure iron, etc.

[0149] 2. Electric arc furnace primary smelting

[0150] The same treatment as in Comparative Example 1.

[0151] 3. Ladle furnace refining

[0152] The same treatment as in Comparative Example 1.

[0153] 4. Vacuum ladle furnace refining

[0154] The same treatment as in Comparative Example 1.

[0155] 5. Forging

[0156] The same process as that of the embodiment of the present invention may be employed.

[0157] 6. Nondestructive testing

[0158] The same process as that of the embodiment of the present invention may be employed.

[0159] 7. Heat treatment

[0160] The same process as that of the embodiment of the present invention may be employed.

[0161] 8. Skinning

[0162] The same process as that of the embodiment of the present invention may be employed.

[0163] 9. Inspection, packaging and storage

[0164] The same process as that of the embodiment of the present invention may be employed.

[0165] <Comparative Example 3>

[0166] Comparative Example 3 is W6Mo5Cr4V2 alloy.

[0167] The alloy comprises the following components in weight percentage: C 0.80-0.90%, Si 0.20-0.45%, Mn 0.15-0.40%, P≤0.030%, S≤0.030%, Cr 3.8-4.4%, W 5.5-6.75%, Mo 4.5-5.5%, V 1.75-2.20%, and Fe as the balance.

[0168] W6Mo5Cr4V2 alloy is usually prepared by the following method:

[0169] 1. Raw material preparation

[0170] Raw materials include scrap steel, ferrochrome, ferromolybdenum, ferrovanadium, ferrosilicon, ferromanganese, pure iron, etc.

[0171] 2. Electric arc furnace primary smelting

[0172] The same treatment as in Comparative Example 1.

[0173] 3. Ladle furnace refining

[0174] The same treatment as in Comparative Example 1.

[0175] 4. Vacuum ladle furnace refining

[0176] The same treatment as in Comparative Example 1.

[0177] 5. Forging

[0178] The same process as that of the embodiment of the present invention may be employed.

[0179] 6. Nondestructive testing

[0180] The same process as that of the embodiment of the present invention may be employed.

[0181] 7. Heat treatment

[0182] The same process as that of the embodiment of the present invention may be employed.

[0183] 8. Skinning

[0184] The same process as that of the embodiment of the present invention may be employed.

[0185] 9. Inspection, packaging and storage

[0186] The same process as that of the embodiment of the present invention may be employed.

[0187] <Performance test and data>

[0188] The alloy prepared in the embodiment of the present invention was subjected to the following performance test together with comparative examples 1, 2 and 3.

[0189] (1) Maximum operating temperature

[0190] The maximum operating temperatures of the embodiments of the present invention, comparative examples 1, 2 and 3 are shown in Table 2 below:

[0191] Table 2. Comparison of the maximum operating temperatures of various alloys

[0192]

[0193] As shown in Table 2, the nickel-based high-temperature alloy of the embodiment of the present invention has a significantly improved operating temperature compared with the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy in the prior art.

[0194] (2) High temperature strength

[0195] The tensile strength Rm and yield strength Rp0.2 of the embodiment of the present invention, comparative example 1, comparative example 2 and comparative example 3 at a test high temperature of 650° C. are shown in Table 3 below:

[0196] Table 3. Comparison of strength of various alloys at 650℃

[0197]

[0198] As shown in Table 2, the nickel-based high-temperature alloy of the embodiment of the present invention has greatly improved strength at high temperatures compared with the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy in the prior art.

[0199] (3) Grain size

[0200] The grain sizes of the embodiment of the present invention, comparative example 1, comparative example 2 and comparative example 3 are shown in Table 4 below:

[0201] Table 4. Grain size comparison of various alloys

[0202] alloy Grain size, grade The added value of the grain size level of the present invention is Comparative Example 1 (4Cr5MoSiV1) 5 3 Comparative Example 2 (3Cr2W8V) 6 2 Comparative Example 3 (W6Mo5Cr4V2) 6 2 Alloys of the present invention 8 /

[0203] As shown in Table 4, the nickel-based high-temperature alloy of the embodiment of the present invention has a finer grain size than the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy in the prior art.

[0204] (4) High temperature antioxidant performance

[0205] The antioxidant properties of the embodiments of the present invention, comparative examples 1, 2 and 3 at a test high temperature of 1000° C. are shown in Table 5 below:

[0206] Table 5. Comparison of oxidation resistance of various alloys at 1000℃ test high temperature

[0207]

[0208] As shown in Table 4, the high-temperature oxidation resistance of the nickel-based high-temperature alloy of the embodiment of the present invention is significantly improved compared with the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy in the prior art.

[0209] (5) Long-lasting performance

[0210] The durability of the embodiments of the present invention, comparative examples 1, 2 and 3 at a test high temperature of 650° C. is shown in Table 6 below:

[0211] Table 5. Comparison of the rupture performance of various alloys at a high test temperature of 650°C

[0212]

[0213] As shown in Table 5, the nickel-based high-temperature alloy of the embodiment of the present invention has a significantly improved durability compared with the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy in the prior art.

[0214] (6) Fatigue strength performance

[0215] According to GBT 4337-1984 "Metal Rotational Bending Fatigue Test Method", the maximum fatigue strength (100h fracture) of the test material at 650°C. The fatigue strength performance of the embodiment of the present invention, comparative example 1, comparative example 2, and comparative example 3 at the test high temperature of 650°C is shown in Table 6 below:

[0216] Table 6. Comparison of fatigue strength performance of various alloys at 650℃ test high temperature

[0217] alloy 650℃ fatigue strength, MPa The improvement ratio of fatigue strength of the alloy at 650℃, % Comparative Example 1 (4Cr5MoSiV1) 212 106.6％ Comparative Example 2 (3Cr2W8V) 258 69.8％ Comparative Example 3 (W6Mo5Cr4V2) 302 45.0％ Alloys of the present invention 438 /

[0218] As shown in Table 6, the nickel-based high-temperature alloy of the embodiment of the present invention has better fatigue strength performance than the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy in the prior art.

[0219] (7) Service life

[0220] The alloys of the embodiment of the present invention, comparative example 1, comparative example 2, and comparative example 3 were respectively made into nickel-copper alloy hot extrusion dies, and then their service life was evaluated by the number of hot extrusions, as shown in Table 7 below:

[0221] Table 7. Comparison of service life of nickel-copper alloy hot extrusion dies made of various alloys

[0222] alloy Service life, times Increased service life ratio Comparative Example 1 (4Cr5MoSiV1) 5500 355％ Comparative Example 2 (3Cr2W8V) 8600 191％ Comparative Example 3 (W6Mo5Cr4V2) 16500 52％ Alloys of the present invention 25000 /

[0223] As shown in Table 7, the nickel-based high-temperature alloy of the embodiment of the present invention has a longer service life than the 4Cr5MoSiV1 alloy, 3Cr2W8V alloy, and W6Mo5Cr4V2 alloy of the prior art.

[0224] The above embodiments are only specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the scope of protection of the present invention.

Claims

1. A high temperature alloy for copper-nickel alloy hot extrusion die, characterized in that: The alloy comprises the following components in weight percentage: C 0.02-0.08%, Si≤0.15%, Mn≤0.15%, P≤0.01%, S≤0.01%, Cr 14.0-17.0%, Mo 7.5-9.5%, Nb 2.2-2.6%, Al 1.0-1.6%, Ti 2.2-2.8%, B 0.005-0.015%, Zr 0.01-0.05%, Fe 21.0-24.0%, and Ni as the balance.

2. A method for preparing a high-temperature alloy for a copper-nickel alloy hot extrusion die as claimed in claim 1, characterized in that: The alloy raw material is firstly melted by vacuum induction and then cast into an ingot, and then electroslag remelted to obtain an electroslag ingot, and then the electroslag ingot is subjected to multi-fire forging and then heat treatment.

3. The method for preparing a high temperature alloy for a copper-nickel alloy hot extrusion die according to claim 2, characterized in that: in, The vacuum induction melting includes the following processes: 1) Loading; 2) Vacuuming: Turn on the mechanical pump to draw a vacuum, the power supply is 50-70KW; When the vacuum degree is ≤1000Pa, turn on the Roots pump to evacuate the vacuum; When the vacuum degree is ≤1Pa, the power is increased to 120-150KW; When the vacuum degree is ≤1Pa, open the high vacuum valve; 3) Melting: The vacuum degree during the melting period is ≤1Pa, and the vacuum degree is maintained at ≤0.067Pa during the melting period. After melting, the temperature is measured and samples are taken; 4) Refining: The vacuum degree during the refining period is ≤1Pa, the refining temperature is controlled at 1620~1660℃, the refining time is ≥30 minutes, and after the refining, the temperature is measured and samples are taken to prepare for furnace reversal and steel tapping; 5) Casting: Stir for 3-5 minutes before tapping, then cast the steel to obtain a steel ingot.

4. The method for preparing a high-temperature alloy for a copper-nickel alloy hot extrusion die according to claim 3, characterized in that: in, The Mn in the alloy is provided by the raw material electrolytic manganese, the Ti is provided by the raw material pure titanium, the B is provided by the raw material ferroboron, and the Zr is provided by the raw material metal zirconium; Electrolytic manganese and pure titanium are added after 10-20 minutes of refining in the refining period; Ferroboron and metallic zirconium are added 5 minutes before steelmaking.

5. The method for preparing a high temperature alloy for a copper-nickel alloy hot extrusion die according to claim 2, characterized in that: in, The electroslag remelting includes the following processes: 1) Arcing and slag-melting stage: the current is gradually increased from 1500A to 5000A, and the slag-melting time is not less than 40 minutes; 2) Current increase stage: the current gradually increases from 5000A to 8000A, which takes 25 minutes; 3) Melting stage: the voltage is stable, and the electrode is remelted using a constant current of 7500-8000A; 4) Feeding stage: gradually reduce the voltage and current, the current gradually drops to 2000A, and the feeding time is not less than 30 minutes.

6. The method for preparing a high temperature alloy for a copper-nickel alloy hot extrusion die according to claim 5, characterized in that: in, The arcing and slagging stage includes the following process of gradually increasing current: Current 1500A, maintained for at least 5 minutes; Current 2000A, maintained for at least 5 minutes; Current 2500A, maintained for at least 5 minutes; Current 3000A, maintained for at least 5 minutes; Current 3500A, maintained for at least 5 minutes; Current 4000A, maintained for at least 5 minutes; Current 4500A, maintained for at least 5 minutes; The current is 5000A and maintained for at least 5 minutes.

7. The method for preparing a high temperature alloy for a copper-nickel alloy hot extrusion die according to claim 5, characterized in that: in, The current increasing stage includes the following current gradually increasing process: Current 5500A, maintain for 5 minutes; Current 6000A, maintain for 5 minutes; Current 6500A, maintain for 5 minutes; Current 7000A, maintain for 5 minutes; Current 7500A, maintain for 5 minutes.

8. The method for preparing a high-temperature alloy for a copper-nickel alloy hot extrusion die according to claim 2, Features: in, The multi-fire forging process includes the following steps: 1) Continuously raise the temperature to 600°C and keep it for 1 hour; 2) Continuously raise the temperature to 800°C and keep it for 1 hour; 3) Continuously heating to the soaking temperature and starting forging, keeping the temperature for 1 to 4 hours, wherein the soaking temperature is a constant temperature of 1100 to 1200°C; 4) Final forging temperature ≥930℃.

9. The method for preparing a high temperature alloy for a copper-nickel alloy hot extrusion die according to claim 8, characterized in that: in, When the electroslag ingot is 0.5 tons, the insulation time is 1 to 3 hours; when the electroslag ingot is 1 ton, the insulation time is 3 to 4 hours.

10. The method for preparing a high temperature alloy for a copper-nickel alloy hot extrusion die according to claim 2, characterized in that: in, The heat treatment includes the following processes: 1) Solid solution: Solution temperature 1000 ~ 1060 ℃, holding time T minutes, T = 1.2D, where D represents the outer diameter of the forging material, the unit is mm, T is not less than 60 minutes and not more than 120 minutes; After the heat preservation is completed, it is taken out of the furnace and water-cooled; 2) Time limit: Aging temperature 710-730℃, keep warm for 8-10 hours; Then, the furnace is cooled to 610-630°C and kept at this temperature for 8-10 hours; Then, air cool to room temperature.

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