阅读说明：本技术 核反应堆大规格镍基合金开坯锻造方法 (Cogging forging method for large-size nickel-based alloy of nuclear reactor ) 是由 陈飞 宣雨澄 杨婧婧 任茂荣 金屹 于 2020-04-13 设计创作，主要内容包括：本发明公开了一种核反应堆大规格镍基合金开坯锻造方法,该开坯锻造方法包括以下步骤：⑴首次锻造：采用始锻温度1180℃～1140℃、终锻温度980℃～920℃,总镦粗比为3.0～3.1,拔长比2.0～2.1；⑵后续锻造：始锻温度1200℃～1160℃、终锻温度980℃～920℃,对镍基合金锻坯进行大变形锻造,该火次的变形量为40%；⑶末次锻造：始锻温度1150℃～1110℃、终锻温度980℃～920℃,锻造过程中总变形量75%,各火次的变形量≥15%。该开坯锻造方法不仅能有效控制锻件的成形,防止热裂和冷裂的发生,而且能有效控制锻件组织的均匀性,从而获得晶相组织均匀性较好的锻件。(The invention discloses a cogging forging method for a large-size nickel-based alloy of a nuclear reactor, which comprises the following steps of: firstly forging: the initial forging temperature is 1180-1140 ℃, the final forging temperature is 980-920 ℃, the total upsetting ratio is 3.0-3.1, and the drawing ratio is 2.0-2.1; and secondly, subsequent forging: the initial forging temperature is 1200-1160 ℃, the final forging temperature is 980-920 ℃, and the large deformation forging is carried out on the nickel-based alloy forging stock, wherein the deformation amount of the heat is 40%; the last forging: the initial forging temperature is 1150-1110 ℃, the final forging temperature is 980-920 ℃, the total deformation in the forging process is 75 percent, and the deformation of each heating time is more than or equal to 15 percent. The cogging forging method can effectively control the forming of the forge piece, prevent the occurrence of hot cracking and cold cracking, and effectively control the uniformity of the forge piece structure, thereby obtaining the forge piece with better uniformity of the crystal phase structure.)

1. A cogging forging method for large-size nickel-based alloy of a nuclear reactor is characterized by comprising the following steps: the cogging forging method comprises the following steps:

firstly forging: performing multi-fire forging on the nickel-based alloy ingot at the initial forging temperature of 1180-1140 ℃ and the final forging temperature of 980-920 ℃, and completing cast structure transformation through pre-upsetting, rolling and drawing; the total upsetting ratio is 3.0-3.1, and the drawing ratio is 2.0-2.1;

and secondly, subsequent forging: controlling the grain structure of the forging by carrying out subsequent forging on the forging, wherein the initial forging temperature is 1200-1160 ℃, the final forging temperature is 980-920 ℃, and the large-deformation forging is carried out on the nickel-based alloy forging stock, and the deformation amount of the heat is 40%;

the last forging: the nickel-based alloy forging stock is subjected to one-time fire forging, so that the structure of the forging stock is uniformly refined, the initial forging temperature is 1150-1110 ℃, the final forging temperature is 980-920 ℃, the total deformation amount in the forging process is 75%, and the deformation amount of each fire time is more than or equal to 15%.

2. The cogging forging method according to claim 1, characterized in that: the nickel base alloy forging stock is sequentially subjected to the following steps: punching a cylinder hole: punching a cylindrical hole along the axial lead direction of the nickel-based alloy forging stock, wherein the punched cylindrical hole is a through hole; reaming by using a core rod: and penetrating a round-rod-shaped reaming core rod into the punching cylinder hole, pressing the periphery of the short cylindrical nickel-based alloy forging stock with the punching cylinder hole by the flat anvil, and continuously rotating the nickel-based alloy forging stock on the reaming core rod to enable the diameter of the central cylinder hole of the nickel-based alloy forging stock to be twice of that of the core rod so as to form the reaming forging stock.

3. The cogging forging method according to claim 2, characterized in that: penetrating a drawing mandrel with the diameter being twice that of the hole expanding mandrel into a cylinder hole of the nickel-based alloy hole expanding forging blank, and forging and pressing the hole expanding forging blank by using an upper flat anvil to form a section of cylindrical drawing forging blank with different outer diameters, wherein the outer diameter of the section of cylindrical drawing forging blank is larger than that of the other section of cylindrical drawing forging blank; the total drawing ratio of the drawn forging stock is 3.5-3.8; then, a forming core rod with two sections of different rod diameters is penetrated into the cylindrical hole of the drawn forging stock, and the sections of the different rod diameters of the forming core rod are connected by a conical surface; forging and pressing the cylinder wall of the drawn nickel-based alloy forging blank by using a forming flat anvil, and continuously rotating the base alloy forging blank on the forming core rod to forge and press the base alloy forging blank into a formed cylinder blank; the forging surface of the forming flat anvil is a folded surface which is matched with the shape of the rod surface of the forming core rod.

4. The cogging forging method according to claim 3, characterized in that: air-cooling the formed barrel blank to 400-500 ℃, then sending the barrel blank into a heating furnace to be heated to 640-660 ℃, preserving heat for 3-5 hours, then cooling the barrel blank to 120 ℃ along with the furnace, discharging the barrel blank out of the furnace and air-cooling the barrel blank to room temperature; and then feeding the formed cylinder blank into a heating furnace, heating to 940-960 ℃, preserving heat for 7 hours, taking out the cylinder blank from the heating furnace, and air-cooling to form the nickel-based alloy cylinder forging.

5. The cogging forging method according to claim 1, characterized in that: the upsetting ratio of each forging of the nickel-based alloy forging stock is 1.5-1.6.

Technical Field

The invention relates to a forging and forming process of a large-size structural member of a nuclear reactor, in particular to a forging process method of various nickel-based alloy supporting pieces in a nuclear reactor island, a middle ring of a nickel-based alloy member in the nuclear reactor, a flow distribution skirt cylinder of a member in the nuclear reactor, a pump shell outer ring, a U-shaped pipe and the like.

Background

Compared with the common alloy, the nickel-based alloy has the advantages of good hardness and strength, corrosion resistance, oxidation resistance, wear resistance, high temperature resistance and radiation resistance, and is a preferred material for manufacturing internal components of nuclear reactors. But the processing and forming which meets the quality requirements are difficult, especially nuclear power stacks, moving stack weight reduction manufacturing, weld joint reduction and in-service inspection reduction, the integrated forging and forming of deep holes, special-shaped, spherical multi-joint pipes, large-diameter cylinders and ring pieces are more difficult, and the requirements on mechanical properties and metallographic structures are difficult to achieve.

Because the nickel-based alloy has a single austenite structure and does not have solid phase transformation, the grain size of a forged piece cannot be adjusted through subsequent performance heat treatment, and the structure control in the forging process is particularly critical. In addition, the nickel-based alloy has large deformation resistance, and particularly when the surface temperature of the cast ingot is reduced to be lower than the finish forging temperature, the deformation resistance is increased sharply, and the surface cracking phenomenon is easy to generate. Therefore, the nickel-based alloy has two key control points in the forging process: firstly, the formability is controlled, namely the occurrence of hot cracking and cold cracking is prevented; on the other hand, the control of the structure uniformity of the forged piece is realized, and the forged piece with better radial structure uniformity is obtained by controlling the technological parameters such as temperature, heat, strain rate, deformation and the like. Therefore, when designing the forging process of the nickel-based alloy, manufacturing links such as heating before forging, homogenization, forging temperature, heat number, strain rate, deformation, cooling mode and the like must be scientifically and reasonably designed.

France, japan, germany and the united states are at the international leading level, and the key complex forging manufacturing technology of nickel-based alloys has reached a high degree of specialization. After the 21 st century, China put forward a policy of 'actively developing nuclear power', and the China vigorously develops nuclear power at an absolutely-free speed in the world and needs to have the capability of research, development, preparation and processing of nuclear power equipment materials in as short a time as possible. At present, nuclear power equipment materials such as austenitic stainless steel SA508-3, 304 and 316, nickel-based nuclear power equipment materials 600, 690 and 750 and the like are made in China, but the technology of independent research and development and manufacturing of key components of a nuclear island is still broken through, particularly, in-pile nickel-based alloy forgings still mainly depend on import, although partial products are broken through, the manufacturing mode of 'quantity to quality' is still taken as the main mode, the control manufacturing technology of the thermomechanical treatment process is not mastered, and the key technology breaking through becomes a major scientific and technical challenge to be solved urgently for in-pile complex key nickel-based alloy components in China.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a cogging forging method for large-size nickel-based alloy of a nuclear reactor, which can effectively control the forming of a forging, prevent the occurrence of hot cracking and cold cracking, and effectively control the uniformity of the forging structure, thereby obtaining the forging with better uniformity of a crystal phase structure.

In order to solve the technical problem, the cogging forging method for the large-size nickel-based alloy of the nuclear reactor comprises the following steps of:

firstly forging: performing multi-fire forging on the nickel-based alloy ingot at the initial forging temperature of 1180-1140 ℃ and the final forging temperature of 980-920 ℃, and completing cast structure transformation through pre-upsetting, rolling and drawing; the total upsetting ratio is 3.0-3.1, and the drawing ratio is 2.0-2.1;

and secondly, subsequent forging: controlling the grain structure of the forging by carrying out subsequent forging on the forging, wherein the initial forging temperature is 1200-1160 ℃, the final forging temperature is 980-920 ℃, and the large-deformation forging is carried out on the nickel-based alloy forging stock, and the deformation amount of the heat is 40%;

the last forging: the nickel-based alloy forging stock is subjected to one-time fire forging, so that the structure of the forging stock is uniformly refined, the initial forging temperature is 1150-1110 ℃, the final forging temperature is 980-920 ℃, the total deformation amount in the forging process is 75%, and the deformation amount of each fire time is more than or equal to 15%.

Further, the nickel base alloy forging stock is sequentially subjected to the following steps: punching a cylinder hole: punching a cylindrical hole along the axial lead direction of the nickel-based alloy forging stock, wherein the punched cylindrical hole is a through hole; reaming by using a core rod: and penetrating a round-rod-shaped reaming core rod into the punching cylinder hole, pressing the periphery of the short cylindrical nickel-based alloy forging stock with the punching cylinder hole by the flat anvil, and continuously rotating the nickel-based alloy forging stock on the reaming core rod to enable the diameter of the central cylinder hole of the nickel-based alloy forging stock to be twice of that of the core rod so as to form the reaming forging stock.

Further, penetrating a drawing core rod with the diameter being twice that of the hole expanding core rod into a cylinder hole of the nickel-based alloy hole expanding forging blank, and forging and pressing the hole expanding forging blank by using the flat anvil to form a section of cylindrical drawing forging blank with different outer diameters, wherein the outer diameter of the cylindrical drawing forging blank is larger than that of the other section of cylindrical drawing forging blank; the total drawing ratio of the drawn forging stock is 3.5-3.8; then, a forming core rod with two sections of different rod diameters is penetrated into the cylindrical hole of the drawn forging stock, and the sections of the different rod diameters of the forming core rod are connected by a conical surface; forging and pressing the cylinder wall of the drawn nickel-based alloy forging blank by using a forming flat anvil, and continuously rotating the base alloy forging blank on the forming core rod to forge and press the base alloy forging blank into a formed cylinder blank; the forging surface of the forming flat anvil is a folded surface which is matched with the shape of the rod surface of the forming core rod.

Further, after the formed barrel blank is cooled to 400-500 ℃ in air, the formed barrel blank is sent to a heating furnace to be heated to 640-660 ℃, and after the temperature is kept for 3-5 hours, the formed barrel blank is cooled to 120 ℃ along with the furnace and then is taken out of the furnace to be cooled to room temperature in air; and then feeding the formed cylinder blank into a heating furnace, heating to 940-960 ℃, preserving heat for 7 hours, taking out the cylinder blank from the heating furnace, and air-cooling to form the nickel-based alloy cylinder forging.

Further, the upsetting ratio of each forging of the nickel-based alloy forging stock is 1.5-1.6.

The cogging forging method of the invention has the following remarkable advantages: the first forging procedure, the subsequent forging procedure and the last forging procedure are adopted, and the corresponding initial forging temperature and final forging temperature are respectively adopted, so that the forging stock of the nickel-based alloy forging piece can be fully heated and the internal structure is homogenized; because the large-size forged piece for the nuclear island has large section size, a larger temperature gradient can be formed in the blank by a direct continuous heating method, the invention adopts different heating and heat preservation specifications according to the characteristics of the nickel-based alloy material to ensure that the large-size and large-section forged piece can be uniformly and thoroughly heated, so that the heating temperature between the core part and each region on the surface of the nickel-based alloy forged piece is consistent, the temperature stress caused by the temperature difference of the section is avoided, thereby causing the cracking of the steel ingot of the nickel-based alloy forging, avoiding the internal structure defect caused by the heating and the temperature rise of the nickel-based alloy casting blank, meanwhile, the initial forging temperature, the final forging temperature and the heating speed determined by the invention enable the nickel-based alloy forging blank to be formed in a better plastic state, thereby effectively preventing overheating and overburning and ensuring the sufficient recrystallization of the forging, thereby obtaining better recrystallization texture and greatly improving the metal plasticity and the quality of the forged piece.

Detailed Description

The cogging forging method for large-size nickel-based alloy of nuclear reactor of the present invention is described in detail with reference to two embodiments.

The first embodiment is as follows:

forging for the first time: performing multi-fire forging on the nickel-based alloy ingot at the initial forging temperature of 1180 ℃ and the final forging temperature of 980 ℃, and completing cast structure transformation through pre-upsetting, rounding and drawing; the total upsetting ratio is 3.0, and the drawing ratio is 2.0; subsequent forging: controlling the grain structure of the forging by carrying out subsequent forging on the forging, wherein the initial forging temperature is 1200 ℃, the final forging temperature is 980 ℃, the large-deformation forging is carried out on the nickel-based alloy forging stock, and the deformation amount of the heat is 40%; and (3) final forging: the method comprises the following steps of carrying out primary fire forging on a nickel-based alloy forging stock to enable the forging stock to be uniform in structure and refined, wherein the initial forging temperature is 1150 ℃, the final forging temperature is 980 ℃, the total deformation amount in the forging process is 75%, and the deformation amount of each fire is 18%. Punching a cylinder hole: punching a cylinder hole along the axial lead direction of the short cylindrical forging stock by using a punch, wherein the punched cylinder hole is a through hole, and the diameter of the punched cylinder hole is phi 400 mm; reaming by using a core rod: penetrating a hole-expanding mandrel in the shape of a round rod with the diameter of phi 400mm into a punching cylinder hole, pressing the periphery of a short cylindrical forging stock with the punching cylinder hole by using an upper flat anvil, and continuously rotating the forging stock on the hole-expanding mandrel to enable the diameter of a central cylinder hole of the forging stock to reach phi 800mm to form a hole-expanding forging stock; drawing out a core rod: penetrating a drawing core rod with the diameter of phi 800mm into a cylinder hole of a reaming forging stock, and forging and pressing the reaming forging stock by using an upper flat anvil to form a cylindrical drawing forging stock with different outer diameters, wherein the diameter of one section of the cylindrical drawing forging stock is larger than that of the other section of the cylindrical drawing forging stock; the total drawing ratio of the drawn forging stock is 3.5-3.8; forming a barrel blank; penetrating a forming core rod with two sections of different rod diameters into a cylindrical hole of a drawn forging stock, wherein the different rod diameter sections of the forming core rod are connected by a conical surface; forging and pressing the cylinder wall of the drawn forging stock by a forming flat anvil, continuously rotating the forging stock on the forming core rod, and forging and pressing the forging stock into a formed cylinder stock; the forging surface of the forming flat anvil is a folded surface, and the folded surface is matched with the shape of the rod surface of the forming mandrel; forming and forging the cylinder blank to form an integrated cylinder forging; heat treatment after forging: and air-cooling the connecting pipe blank to 450 ℃, then sending the connecting pipe blank into a heating furnace, heating to 650 ℃, keeping the temperature for 4 hours, cooling to 120 ℃ along with the furnace, discharging, and placing in air for air cooling to room temperature. And cooling to room temperature, then sending the connecting pipe blank into a heating furnace, heating to 950 ℃, preserving heat for 7 hours, taking out from the heating furnace, and air-cooling to room temperature.

Example two:

forging for the first time: forging the nickel-based alloy ingot with multiple fires at the initial forging temperature of 1140 ℃ and the final forging temperature of 920 ℃, and finishing cast structure transformation through pre-upsetting, rounding and drawing; the total upsetting ratio is 3.1, and the drawing ratio is 2.1; subsequent forging: controlling the grain structure of the forging by carrying out subsequent forging on the forging, wherein the initial forging temperature is 1160 ℃, the final forging temperature is 920 ℃, and the large-deformation forging is carried out on the nickel-based alloy forging stock, and the deformation amount of the heat is 40%; secondary forging: the method comprises the following steps of carrying out primary fire forging on a nickel-based alloy forging stock to enable the forging stock to be uniform in structure and refined, wherein the initial forging temperature is 1110 ℃, the final forging temperature is 920 ℃, the total deformation amount in the forging process is 75%, and the deformation amount of each fire is 20%. Punching a cylinder hole: punching a cylinder hole along the axial lead direction of the short cylindrical forging stock by using a punch, wherein the punched cylinder hole is a through hole, and the diameter of the punched cylinder hole is phi 400 mm; reaming by using a core rod: penetrating a hole-expanding mandrel in the shape of a round rod with the diameter of phi 400mm into a punching cylinder hole, pressing the periphery of a short cylindrical forging stock with the punching cylinder hole by using an upper flat anvil, and continuously rotating the forging stock on the hole-expanding mandrel to enable the diameter of a central cylinder hole of the forging stock to reach phi 800mm to form a hole-expanding forging stock; drawing out a core rod: penetrating a drawing core rod with the diameter of phi 800mm into a cylinder hole of a reaming forging stock, and forging and pressing the reaming forging stock by using an upper flat anvil to form a cylindrical drawing forging stock with different outer diameters, wherein the diameter of one section of the cylindrical drawing forging stock is larger than that of the other section of the cylindrical drawing forging stock; the total drawing ratio of the drawn forging stock is 3.5-3.8; forming a barrel blank; penetrating a forming core rod with two sections of different rod diameters into a cylindrical hole of a drawn forging stock, wherein the different rod diameter sections of the forming core rod are connected by a conical surface; forging and pressing the cylinder wall of the drawn forging stock by a forming flat anvil, continuously rotating the forging stock on the forming core rod, and forging and pressing the forging stock into a formed cylinder stock; the forging surface of the forming flat anvil is a folded surface, and the folded surface is matched with the shape of the rod surface of the forming mandrel; forming and forging the cylinder blank to form an integrated cylinder forging; heat treatment after forging: and air-cooling the connecting pipe blank to 450 ℃, then sending the connecting pipe blank into a heating furnace, heating to 650 ℃, keeping the temperature for 4 hours, cooling to 120 ℃ along with the furnace, discharging, and placing in air for air cooling to room temperature. And cooling to room temperature, then sending the connecting pipe blank into a heating furnace, heating to 950 ℃, preserving heat for 7 hours, taking out from the heating furnace, and air-cooling to room temperature.