Production process of high-performance nickel-based alloy forged round steel

Abstract

The invention relates to a high-performance nickel-based alloy forged round steel production process, and belongs to the technical field of round steel production in the metallurgical industry. According to the technical scheme, the method comprises homogenization before forging, heating before forging and forging; before forging, the homogenizing furnace temperature is smaller than or equal to 300 DEG C, and the blank is fed into the furnace, heated to 1180-1200 DEG C, cooled to 500 DEG C or below along with the furnace and discharged out of the furnace for air cooling; heating before forging: feeding the blank at the furnace temperature of less than or equal to 700 DEG C into a furnace, heating to 1090-1120 DEG C, and preserving heat for 4-6 hours; and forging is conducted, multi-heating-number forging is adopted, round steel is forged in the last heating number, octagons are forged in other heating numbers, the finish forging temperature of a workpiece in each heating number is larger than or equal to 930 DEG C, and the heat preservation time between the heating numbers is 1-2 h. The preparation method has the beneficial effects that the grain size is more uniform and fine through a grain control technology, so that the strength and the toughness of the material are improved; and in the aspect of deformation strengthening control, the cooperation of the deformation degree and the heat treatment process is accurately mastered, and the material performance is accurately regulated and controlled.

Description

Technical Field

[0001] This invention relates to a production process for high-performance nickel-based alloy forged round steel bars, belonging to the field of round steel bar production technology in the metallurgical industry. Background Technology

[0002] In718 is a high-performance nickel-based superalloy, renowned for its excellent mechanical properties and oxidation resistance at high temperatures. This alloy is widely used in aerospace, energy, and other fields, and is one of the key materials for manufacturing high-performance engines.

[0003] In718's main component is nickel (Ni), and it also contains elements such as chromium (Cr), cobalt (Co), and molybdenum (Mo). It exhibits good strength and oxidation resistance at high temperatures. The mechanical properties of In718 at different temperatures are as follows: at room temperature, the yield strength is approximately 800 MPa, and the tensile strength is approximately 1200 MPa. At 600℃, the yield strength is approximately 500 MPa, and the tensile strength is approximately 800 MPa. At higher temperatures, its strength decreases slightly but remains at a high level. This alloy also possesses good fatigue properties and fracture toughness, making it suitable for environments subjected to long-term cyclic loading.

[0004] In recent years, China has made continuous breakthroughs in the production technology of high-temperature alloys, and the quality of its products has gradually approached international advanced levels. However, in high-end application fields, such as key components of high-performance engines, there is still a certain technological gap. International Situation and Technological Level: Western countries such as the United States and the United Kingdom are in a leading position in the research and application of In718. They possess advanced smelting technologies and strict quality control systems. European and American companies not only focus on improving material performance but also dedicate themselves to developing new high-temperature alloys to meet ever-growing demands. Market Application: In718 is widely used in high-end fields such as aerospace and energy power abroad, with stable and continuously growing market demand. Some large aero-engine manufacturers in the United States are among the main users of this alloy. Research and Development Dynamics: Foreign research institutions are making continuous progress in the optimization of high-temperature alloy composition and microstructure control, dedicated to improving the high-temperature strength and oxidation resistance of materials. Some new processes, such as powder metallurgy technology, have also been introduced into the production of high-temperature alloys abroad to further improve material performance. Overall, foreign countries are in a leading position in the research, production, and application of In718, especially in high-end application fields. While China has made some progress in catching up, there are still gaps in technology and product quality. However, China's cost advantage provides the market with more choices.

[0005] Forging is used to plastically deform metal billets to obtain forgings with specific mechanical properties, shapes, and dimensions. Forging can eliminate defects such as casting porosity that occur during smelting, optimize the microstructure, and preserve intact metal flow lines. However, high-performance nickel-based alloys are prone to cracking and uneven microstructure during existing forging processes, affecting the material's strength and toughness. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance nickel-based alloy forged round steel production process. Through grain control technology, the grain size is made more uniform and fine, thereby improving the strength and toughness of the material. In terms of deformation strengthening control, the precise control of the deformation degree and the heat treatment process is achieved, realizing the precise regulation of material properties and solving the problems existing in the background technology.

[0007] The technical solution of this invention is: A production process for high-performance nickel-based alloy forged round steel includes pre-forging homogenization, pre-forging heating, and forging. Homogenization before forging: The billet with a furnace temperature ≤300℃ is put into the furnace and held for 1.5-2.5 hours. The temperature is then increased to 880-920℃ at a rate of 40-60℃ per hour and held for 1.5-2.5 hours. The temperature is then increased to 1150-1180℃ at a rate of 40-60℃ per hour and held for 24-26 hours. The temperature is then increased to 1180-1200℃ at a rate of 10-20℃ per hour and held for 50-60 hours. The billet is then cooled in the furnace to below 500℃ and then air-cooled. Pre-forging heating: The billet is put into the furnace at a furnace temperature ≤700℃ and held for 2-3 hours. The temperature is then increased to 1000-1020℃ at a rate of 60-90℃ per hour and held for 2-2.5 hours. The temperature is then increased to 1090-1120℃ and held for 4-6 hours. Forging: Multi-fire forging is adopted. The last fire forging is used to form round bars, and the other fire forgings are used to form octagonal bars.

[0008] The pre-forging homogenization process involves: feeding billets at a furnace temperature ≤300℃ into the furnace, holding them at that temperature for 1.5-2.5 hours, increasing the temperature at 40-60℃ per hour for 12-14 hours to 880-920℃, holding them at that temperature for 1.5-2.5 hours, increasing the temperature at 40-60℃ per hour for 5-8 hours to 1150-1180℃, holding them at that temperature for 24-26 hours, increasing the temperature at 10-20℃ per hour for 2-3 hours to 1180-1200℃, holding them at that temperature for 50-60 hours, and then cooling them in the furnace to below 500℃ before air cooling.

[0009] The forging process is as follows: the final forging temperature of the workpiece in each forging cycle is ≥930℃, and the holding time between each forging cycle is 1 to 2 hours.

[0010] The forging process consists of ten passes. In the first pass, the steel is first upset and then drawn into an octagonal shape. In the second to ninth passes, the steel is forged into an octagonal shape with a gradually decreasing cross-section. In the tenth pass, the steel is forged into a round bar.

[0011] The above-mentioned high-performance nickel-based alloy forged round steel production process uses vacuum consumable ingots as the masterbatch, with the following composition: Ni: 50-60%; Cr: 15-20%; Mo: 3-4%; Fe: 18-19%; C: 0.03-0.04%; Si: 0.02-0.06%; Mn: 0.004-0.03%; P: 0.0001-0.0004%; S: 0.0003-0.0004%; Co: 0.20-0.22%; Cu: 0.007-0.009%; Ti: 0.9-1.1%; W: 0.007-0.009%; Al: 0.5-0.6%; Nb: 5.1-5.3%; B: 0.002-0.004%, with the remainder being unavoidable impurities.

[0012] The beneficial effects of this invention are as follows: By employing a multi-stage forging process with an octagonal cross-section combined with strict temperature control, this invention effectively overcomes the problems of easy cracking and uneven microstructure in existing forging processes for high-performance nickel-based alloys. The steel forged using this invention exhibits superior performance in all aspects, meeting the material requirements of high-precision and cutting-edge projects. It has successfully achieved breakthroughs in key core technologies such as the mechanism and control of hot forging cracking in nickel-based alloys, grain control technology, and deformation strengthening control technology. Through grain control technology, the grain size becomes more uniform and finer, improving the strength and toughness of the material. In terms of deformation strengthening control, precise control of the degree of deformation and the coordination of heat treatment processes enables precise regulation of material properties. Attached Figure Description

[0013] Figure 1 This is a cross-sectional schematic diagram of the ten-stage forging process of the present invention; Figure 2 This is a schematic diagram of the octagonal cross-section of the present invention; Detailed Implementation

[0014] The invention will be further described below with reference to the accompanying drawings and examples.

[0015] See attached document Figure 1-2 A high-performance nickel-based alloy forged round steel production process, comprising pre-forging homogenization, pre-forging heating and forging; Homogenization before forging: The billet with a furnace temperature ≤300℃ is put into the furnace and held for 1.5-2.5 hours. The temperature is then increased to 880-920℃ at a rate of 40-60℃ per hour and held for 1.5-2.5 hours. The temperature is then increased to 1150-1180℃ at a rate of 40-60℃ per hour and held for 24-26 hours. The temperature is then increased to 1180-1200℃ at a rate of 10-20℃ per hour and held for 50-60 hours. The billet is then cooled in the furnace to below 500℃ and then air-cooled. Pre-forging heating: The billet is put into the furnace at a furnace temperature ≤700℃ and held for 2-3 hours. The temperature is then increased to 1000-1020℃ at a rate of 60-90℃ per hour and held for 2-2.5 hours. The temperature is then increased to 1090-1120℃ and held for 4-6 hours. Forging: Multi-fire forging is adopted. The last fire forging is used to form round bars, and the other fire forgings are used to form octagonal bars.

[0016] The pre-forging homogenization process involves: feeding billets at a furnace temperature ≤300℃ into the furnace, holding them at that temperature for 1.5-2.5 hours, increasing the temperature at 40-60℃ per hour for 12-14 hours to 880-920℃, holding them at that temperature for 1.5-2.5 hours, increasing the temperature at 40-60℃ per hour for 5-8 hours to 1150-1180℃, holding them at that temperature for 24-26 hours, increasing the temperature at 10-20℃ per hour for 2-3 hours to 1180-1200℃, holding them at that temperature for 50-60 hours, and then cooling them in the furnace to below 500℃ before air cooling. The forging process is as follows: the final forging temperature of the workpiece in each forging cycle is ≥930℃, and the holding time between each forging cycle is 1 to 2 hours.

[0017] The forging process consists of ten passes. In the first pass, the steel is first upset and then drawn into an octagonal shape. In the second to ninth passes, the steel is forged into an octagonal shape with a gradually decreasing cross-section. In the tenth pass, the steel is forged into a round bar.

[0018] The masterbatch uses vacuum consumable ingots, and its chemical composition is as follows: Ni: 50-60%; Cr: 15-20%; Mo: 3-4%; Fe: 18-19%; C: 0.03-0.04%; Si: 0.02-0.06%; Mn: 0.004-0.03%; P: 0.0001-0.0004%; S: 0.0003-0.0004%; Co: 0.20-0.22%; Cu: 0.007-0.009%; Ti: 0.9-1.1%; W: 0.007-0.009%; Al: 0.5-0.6%; Nb: 5.1-5.3%; B: 0.002-0.004%, with the remainder being unavoidable impurities.

[0019] In this embodiment, refer to the appendix Figure 1-2 The production process includes pre-forging homogenization, pre-forging heating, and forging, with specific requirements as follows: 1. Pre-forging homogenization: The base material uses a Φ435mm vacuum consumable ingot, 750mm in length, and weighing 921kg. The composition meets the requirements of the steel grade range: Ni content 53.487%, Fe content 18.2534%, Cr content 18.58%, Mo content 3.189%, Ti content 1.1264%. The surface quality is free of obvious cracks and bumps, and the ends are free of loose cracks. The base material is first machined to a bright, crack-free surface, and then the riser is sawn off. After sawing, flaw detection is performed to ensure clean ends. Forging specifications: Forged into φ250*L (mm) forged round steel. Homogenization process: The billet is fed into the furnace at a furnace temperature ≤300℃ and held for 2 hours; the temperature is increased at 50℃ per hour for 12 hours to 900℃; after holding at 900℃ for 2 hours, the temperature is increased at 50℃ per hour for 6 hours to reach 1160℃; after holding at 1160℃ for 24 hours, the temperature is increased at 15℃ per hour for 2 hours to reach 1190℃; after holding at 1190℃ for 50 hours, the process is stopped, and the billet is cooled in the furnace to 500℃ before being removed from the furnace and air-cooled. 2. Heating process: The billet is put into the furnace at a furnace temperature of ≤700℃, held for 2 hours, then heated to 1000℃ at 80℃ per hour, held for 2 hours, and then heated to 1100℃ at maximum power, held for 4 hours.

[0020] 3. Forging process: Refer to the appendix. Figure 1 , 2 Pre-forging condition: Remove risers from the base material and forge at least two die steels before forging this high-performance nickel-based alloy to ensure that the anvil and hammer are fully preheated.

[0021] Because high-performance nickel-based alloys have high alloying element content, they are prone to cracking during forging. Therefore, a reasonable forging process has been developed to ensure the feasibility of forging.

[0022] In the first forging pass, the workpiece is upset by 200mm, reducing the diameter to 508mm. It is then drawn to an octagonal length of 490mm across its sides. The second to ninth forging passes produce octagonal shapes with cross-sectional lengths of 460mm / 430mm / 400mm / 370mm / 340mm / 310mm / 280mm / 260mm respectively. The tenth forging pass utilizes a round steel forging fixture to achieve a final diameter of 250mm. During each forging pass, the final forging temperature is ≥930℃, with a 2-hour holding time between passes. Attention must be paid to the surface quality of the forgings; forging should be stopped immediately if cracks appear to prevent further damage. The holding time is calculated after the billet has been returned to the furnace and reached the desired temperature.

[0023] (1) First forging: The forging riser end is held by the manipulator clamp, and the forging is upset using a flat anvil. The forging is upset down by 200mm, and the diameter becomes 508mm. Then, it is drawn and reduced in length to forge the circular cross-section into an octagonal cross-section. The cross-section has eight sides: A / B / C / D / E / F / G / H, as shown in the attached figure. Figure 2 As shown, the cross-sectional length is 460mm. Forging is stopped when the forging temperature drops below 930℃, and the billet is stood upright and returned to the furnace. (2) Second to Ninth Fires: After the billet exits the furnace, it is drawn. The single-sided reduction is 5mm to 8mm. Forging is carried out in the order of AE / CG / BF / HD, and the billet is forged into an octagon with a cross-sectional side length of 460mm / 430mm / 400mm / 370mm / 340mm / 310mm / 280mm / 260mm respectively; (3) Tenth forging: round steel is formed using a forging tool called a forging wrench. The wrench core is 250mm, and it is formed in one forging. (4) After forging, air cooling is performed at an ambient temperature of 34.7℃.

[0024] After forging, the product dimensions and performance are tested. Specific data are as follows:

[0025] .

Claims

1. A production process for high-performance nickel-based alloy forged round steel, characterized in that: It includes pre-forging homogenization, pre-forging heating, and forging; Homogenization before forging: The billet with a furnace temperature ≤300℃ is put into the furnace and held for 1.5-2.5 hours. The temperature is then increased to 880-920℃ at a rate of 40-60℃ per hour and held for 1.5-2.5 hours. The temperature is then increased to 1150-1180℃ at a rate of 40-60℃ per hour and held for 24-26 hours. The temperature is then increased to 1180-1200℃ at a rate of 10-20℃ per hour and held for 50-60 hours. The billet is then cooled in the furnace to below 500℃ and then air-cooled. Pre-forging heating: The billet is put into the furnace at a furnace temperature ≤700℃ and held for 2-3 hours. The temperature is then increased to 1000-1020℃ at a rate of 60-90℃ per hour and held for 2-2.5 hours. The temperature is then increased to 1090-1120℃ and held for 4-6 hours. Forging: Multi-fire forging is adopted. The last fire forging is used to form round bars, and the other fire forgings are used to form octagonal bars.

2. The production process for high-performance nickel-based alloy forged round steel according to claim 1, characterized in that: The pre-forging homogenization process involves: feeding billets at a furnace temperature ≤300℃ into the furnace, holding them at that temperature for 1.5-2.5 hours, increasing the temperature at 40-60℃ per hour for 12-14 hours to 880-920℃, holding them at that temperature for 1.5-2.5 hours, increasing the temperature at 40-60℃ per hour for 5-8 hours to 1150-1180℃, holding them at that temperature for 24-26 hours, increasing the temperature at 10-20℃ per hour for 2-3 hours to 1180-1200℃, holding them at that temperature for 50-60 hours, and then cooling them in the furnace to below 500℃ before air cooling.

3. The production process for high-performance nickel-based alloy forged round steel according to claim 1, characterized in that: The forging process is as follows: the final forging temperature of the workpiece in each forging cycle is ≥930℃, and the holding time between each forging cycle is 1 to 2 hours.

4. The production process for high-performance nickel-based alloy forged round steel according to claim 1 or 3, characterized in that: The forging process consists of ten passes. In the first pass, the steel is first upset and then drawn into an octagonal shape. In the second to ninth passes, the steel is forged into an octagonal shape with a gradually decreasing cross-section. In the tenth pass, the steel is forged into a round bar.

5. The production process for high-performance nickel-based alloy forged round steel according to claim 1, characterized in that: The masterbatch uses vacuum consumable ingots, and its chemical composition is as follows: Ni: 50-60%; Cr: 15-20%; Mo: 3-4%; Fe: 18-19%; C: 0.03-0.04%; Si: 0.02-0.06%; Mn: 0.004-0.03%; P: 0.0001-0.0004%; S: 0.0003-0.0004%; Co: 0.20-0.22%; Cu: 0.007-0.009%; Ti: 0.9-1.1%; W: 0.007-0.009%; Al: 0.5-0.6%; Nb: 5.1-5.3%; B: 0.002-0.004%, with the remainder being unavoidable impurities.

Images