High-toughness corrosion-resistant nickel-based alloy and preparation method thereof

Abstract

The present application relates to the technical field of alloy preparation, in particular to a high-toughness corrosion-resistant nickel-based alloy and a preparation method thereof.The high-toughness corrosion-resistant nickel-based alloy according to the present application is composed of the following components in percentage by mass: chromium 17-19%, molybdenum 5.5-6.5%, aluminum 2.3-2.7%, titanium 1.3-1.7%, iron 11-13%, manganese 0.7-0.9%, silicon 0.4-0.6%, carbon 0.05-0.07%, rhenium 0.08-0.12%, ruthenium 0.04-0.06%, germanium 0.01-0.02%, hafnium 0.02-0.04%, and the balance being nickel and inevitable impurities.The present application forms a carbon-oxide composite corrosion-resistant protective layer on the surface of the alloy through the synergistic effect of component design, three-stage atmosphere heat treatment and magnetic field treatment, and at the same time, the core obtains a fine structure with high toughness and strength, so that the nickel-based alloy has both high toughness and strong corrosion resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of alloy preparation, in particular to a high-toughness corrosion-resistant nickel-based alloy and a preparation method thereof. BACKGROUND

[0002] The nickel-based alloy is a kind of high-performance material taking nickel as the main component, and due to its unique physical and chemical properties, the nickel-based alloy performs well in high temperature, corrosion and harsh environment, and becomes an optimal material in the fields of energy and chemical industry.

[0003] In the prior art, the nickel-based alloy faces the dual pressure of toughness reduction and insufficient corrosion resistance in actual service, and the traditional means for improving corrosion resistance, such as increasing chromium and molybdenum elements, often leads to toughness reduction, and when high toughness is ensured, local composition or organization is uneven, which causes the protection ability to be weakened and then leads to the reduction of corrosion resistance. SUMMARY

[0004] The application aims to provide a high-toughness corrosion-resistant nickel-based alloy and a preparation method thereof. The nickel-based alloy solves the problem of incoordination between toughness and corrosion resistance, and is suitable for extreme service conditions which require high toughness and long-term corrosion resistance at the same time.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme:

[0006] A high-toughness corrosion-resistant nickel-based alloy, which is composed of the following components in percentage by mass:

[0007] chromium 17-19%, molybdenum 5.5-6.5%, aluminum 2.3-2.7%, titanium 1.3-1.7%, iron 11-13%, manganese 0.7-0.9%, silicon 0.4-0.6%, carbon 0.05-0.07%, rhenium 0.08-0.12%, ruthenium 0.04-0.06%, germanium 0.01-0.02%, hafnium 0.02-0.04%, and the balance being nickel and inevitable impurities;

[0008] The preparation method of the high-toughness corrosion-resistant nickel-based alloy comprises the following steps:

[0009] (1) Preparation of raw materials: each element raw material is weighed according to the percentage by mass, wherein rhenium, ruthenium, germanium and hafnium are added in the form of intermediate alloy;

[0010] (2) Melting and casting: the raw materials are sequentially placed in a vacuum induction furnace, and are melted under the condition of 1450-1490 DEG C and a vacuum degree of less than or equal to 5 Pa, electromagnetic stirring is used in the whole process, the center magnetic induction intensity of the melt is 30 mT, the casting temperature is 1450-1470 DEG C, a casting mold preheated to 650-750 DEG C is used, and a blank is obtained;

[0011] (3) High-temperature atmosphere heat treatment: Put the blank into the atmosphere sintering furnace, and sequentially perform:

[0012] First segment: Under the protection of inert gas, increase the temperature from room temperature to 1150-1250℃ at a rate of 5-10℃ / min, and keep the temperature for 2-4h;

[0013] Second segment: Perform carburizing treatment at 1280-1320℃ for 3-5h in carbon-silane coupling atmosphere, and control the carbon potential to be 0.95-1.05%;

[0014] Third segment: Switch to reducing atmosphere, keep the temperature at 1150-1250℃ for 1-2h, then control the cooling to below 800℃, and then cool to room temperature in the furnace to obtain the blank;

[0015] (4) Magnetic field-ladder temperature treatment: Put the blank after step (3) vertically along the main axis direction into the magnetic field heat treatment device, increase the temperature from 800℃ to 930-970℃ at a rate of 5-10℃ / min under the longitudinal steady magnetic field environment of 0.8-1.2T, keep the temperature for 1-2h, then decrease the temperature to 630-670℃ at a rate of 2-5℃ / min, keep the temperature for 1.5-2.5h, and finally cool to room temperature in the furnace.

[0016] Further, in the preparation method of the high-toughness corrosion-resistant nickel-based alloy, the rhenium, ruthenium, germanium and hafnium in step (1) are added in the form of nickel-20wt% rhenium, nickel-10wt% ruthenium, nickel-5wt% germanium and nickel-5wt% hafnium intermediate alloys.

[0017] Further, in the preparation method of the high-toughness corrosion-resistant nickel-based alloy, the sequence in step (2) is: first add nickel, chromium and molybdenum, melt after increasing the temperature to 1470-1490℃, then add nickel-rhenium and nickel-ruthenium intermediate alloys, keep the temperature for 5-10 minutes, then decrease the temperature to 1450-1460℃, add iron, manganese, nickel-germanium and nickel-hafnium intermediate alloys, and finally add aluminum, titanium, silicon and carbon, and perform electromagnetic stirring for 12 minutes, and reverse the magnetic field direction every 2 minutes during the stirring process.

[0018] Further, in the preparation method of the high-toughness corrosion-resistant nickel-based alloy, the inert gas in the first segment of step (3) is argon.

[0019] Further, in the preparation method of the high-toughness corrosion-resistant nickel-based alloy, in the second segment of step (3), the carbon-silane coupling atmosphere is a mixed gas of methane, argon and silane, wherein the volume fraction of methane is 1.0-2.0%, the volume fraction of silane is 0.03-0.1%, and the balance is argon, and the total flow rate of the gas is 2L / min.

[0020] Further, in the preparation method of the high-toughness corrosion-resistant nickel-based alloy, in the third paragraph of step (3), the reducing atmosphere is argon and hydrogen mixed gas, the volume ratio of argon to hydrogen is 90:10, the gas flow is 1.5L / min, and after heat preservation, the temperature is reduced to 800 DEG C at a rate of 5 DEG C / min.

[0021] Further, in the preparation method of the high-toughness corrosion-resistant nickel-based alloy, in step (4), the magnetic field heat treatment device is a magnetic field heat treatment furnace, the magnetic field source is a water-cooled copper coil electromagnet or a low-temperature superconducting magnet, the working temperature is room temperature-1200 DEG C, the temperature can be programmed to rise and fall, the magnetic field is 0-1.2T and can be continuously adjusted, and inert gas protection is provided.

[0022] Further, a high-toughness corrosion-resistant nickel-based alloy is prepared by the preparation method of the high-toughness corrosion-resistant nickel-based alloy in any one of the above.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] 1、In the present application, high nickel content provides a high toughness matrix for the material, the optimized combination of chromium-molybdenum-iron lays a wide corrosion-resistant foundation, the coordinated ratio of aluminum-titanium elements forms a coherent ordered gamma' strengthening phase, which realizes strengthening while minimizing damage to toughness, rhenium can enhance the interatomic bonding force near the grain boundary by solid solution strengthening in the matrix, reduce defects at the grain boundary, and at the same time, cooperates with other elements to inhibit the migration of impurities to the grain boundary, further assisting in purifying the grain boundary and enhancing the organizational stability, ruthenium can refine the precipitated phase gamma' phase in the alloy and inhibit its coarsening at high temperature, while enhancing the bonding stability between the precipitated phase and the matrix, thereby stabilizing the overall organization, hafnium can preferentially combine with impurity oxygen and nitrogen at the grain boundary to form stable compounds, which exist in the form of fine particles at the grain boundary, avoiding the aggregation and segregation of impurities at the grain boundary, thereby realizing the effect of purifying the grain boundary, the micro-alloying of rhenium, ruthenium, hafnium and germanium has the synergistic effect of purifying the grain boundary, stabilizing the organization, improving the interface and enhancing the corrosion resistance, and the strict limitation of impurities such as carbon, silicon and manganese inhibits the generation of coarse brittle phases and harmful phases from the source, avoiding them from becoming crack sources and corrosion sensitive points, and the precise nickel-based alloy composition design provides a material basis for solving the contradiction between toughness and corrosion resistance.

[0025] 2、In the application, by carrying out high-temperature precision carburizing in a carbon-silane coupling atmosphere, an ultra-thin, dense and chromium-silicon-rich carbon-oxide composite corrosion-resistant protective layer is generated in situ on the surface layer of the alloy, the active silicon decomposed from silane and chromium and nickel form a nanosilicide three-nickel and silicon dioxide-trioxide chromium precursor film, which not only hinders the continuous growth of carbides, but also provides a chromium-rich vacancy channel for the subsequent reduction section, so that the surface layer has excellent passivation ability while maintaining high hardness, and can resist chloride ion and sulfide corrosion in harsh environments, the carbon potential and time control ensure that the carburizing depth is less than or equal to 30 microns, without affecting the toughness of the core, and the magnetic field-step temperature treatment applies a 0.8-1.2T stable magnetic field along the main shaft, disturbs the solute diffusion field, and cooperates with the fine temperature stage, so that the size of the gamma prime phase is locked in a suitable range, the uniformity is improved, and the width of the continuous brittle phase at the grain boundary is reduced, so that the alloy finally obtains fine-grained, toughened grain boundaries and uniform strengthening phases, and has excellent impact toughness and corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A flowchart of a preparation method of a high-toughness corrosion-resistant nickel-based alloy is provided. DETAILED DESCRIPTION

[0027] The technical solutions in the experiments will be described clearly and completely in combination with the experiments of the application. Obviously, the described experiments are only a part of the experiments of the application, rather than all the experiments. Based on the experiments in the application, all other experiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0028] It should be noted that the raw materials used in the following experiments are all commercially available.

[0029] Example 1

[0030] Alloy raw material preparation step:

[0031] The raw materials of each element are accurately weighed according to the mass percentage, and the total weight is 50 kg. The specific composition is as follows: chromium 18.0%, molybdenum 6.0%, aluminum 2.5%, titanium 1.5%, iron 12.0%, manganese 0.8%, silicon 0.5%, carbon 0.06%, the balance is nickel and unavoidable impurities, trace elements rhenium 0.10%, ruthenium 0.05%, germanium 0.015%, hafnium 0.03% are added in the form of nickel-20wt% rhenium, nickel-10wt% ruthenium, nickel-5wt% germanium, nickel-5wt% hafnium intermediate alloy;

[0032] Melting and casting step:

[0033] Nickel, chromium and molybdenum are first added, and then the temperature is raised to 1480℃ for melting, after which nickel-rhenium and nickel-ruthenium intermediate alloys are added, the temperature is maintained for 7 minutes, and then the temperature is lowered to 1455℃, iron, manganese, nickel-germanium and nickel-hafnium intermediate alloys are added, and finally aluminum, titanium, silicon and carbon are added. During the entire melting process, electromagnetic stirring is continuously applied, the magnetic induction intensity at the center of the melt is 30mT, the electromagnetic stirring is 12 minutes, the magnetic field direction is reversed every 2 minutes during the stirring process, after the refining is completed, the alloy liquid is poured into a high-strength graphite mold which is preheated to 700℃ in a box-type resistance furnace and maintained for more than 2h at a pouring temperature of 1460℃, and a cylindrical as-cast billet is obtained;

[0034] High-temperature atmosphere heat treatment step:

[0035] First-stage homogenization treatment: the as-cast billet is loaded into the effective heating zone of a horizontal atmosphere sintering furnace, high-purity argon (purity ≥ 99.999%) is introduced into the furnace as a protective gas, the gas flow is set to 1.0L / min, then the temperature is raised from room temperature to 1200℃ at a heating rate of 7℃ / min, and after reaching the target temperature, the temperature is maintained for 3h;

[0036] Second-stage precision carburizing treatment: after the first-stage maintenance is completed, the atmosphere in the furnace is converted to a mixed gas composed of 1.5% by volume of methane, 0.07% by volume of silane, and the balance of argon by means of an atmosphere switching system, the total flow rate of the mixed gas is set to 2.0L / min, at the same time, the furnace temperature is raised from 1200℃ to 1300℃ at a rate of 5℃ / min, and the temperature is maintained at 1300℃ for 4h, and the carbon potential in the furnace is stably controlled at 1.0%;

[0037] Third-stage reduction purification treatment: after the second-stage maintenance is completed, the atmosphere in the furnace is converted to a reducing mixed gas composed of 90% high-purity argon and 10% hydrogen by means of an atmosphere switching system, the total flow rate of the mixed gas is set to 1.5L / min, the furnace temperature is lowered from 1300℃ to 1200℃, and the temperature is maintained at 1200℃ for 1.5h, after the maintenance is completed, the programmed cooling is started, and the billet is cooled to 800℃ at a controlled cooling rate of 5℃ / min, after reaching 800℃, the heating power is turned off, and the billet is naturally cooled to room temperature along with the furnace;

[0038] Magnetic field-ladder temperature treatment step:

[0039] The billet after high-temperature atmosphere heat treatment is loaded into a special longitudinal steady magnetic field heat treatment furnace, and the long axis direction of the billet is ensured to be consistent with the magnetic field direction, the magnetic field generating device is started, a steady strong magnetic field with a strength of 1.0T is generated, in the magnetic field environment, the temperature is raised from 800℃ to 950℃ at a heating rate of 8℃ / min, and the temperature is kept at 950℃ for 1.5h, after the holding is completed, the furnace temperature is slowly cooled from 950℃ to 650℃ at a cooling rate of 3℃ / min, and the temperature is kept at 650℃ for 2h, after the holding is completed, all power supplies are turned off, and the billet is cooled to room temperature in the state of continuously applied magnetic field.

[0040] Example 2

[0041] Alloy raw material preparation step:

[0042] The raw materials of each element are accurately weighed according to the mass percentage, and the total weight is 50kg, and the specific composition is as follows: chromium 19.0%, molybdenum 5.5%, aluminum 2.7%, titanium 1.3%, iron 13.0%, manganese 0.7%, silicon 0.6%, carbon 0.05%, the balance is nickel and unavoidable impurities, trace elements rhenium 0.12%, ruthenium 0.04%, germanium 0.02%, hafnium 0.02% are added in the form of nickel-20wt% rhenium, nickel-10wt% ruthenium, nickel-5wt% germanium, nickel-5wt% hafnium intermediate alloy respectively;

[0043] Melting and casting step:

[0044] First, add nickel, chromium and molybdenum, heat to 1470℃ to melt, then add nickel-rhenium and nickel-ruthenium intermediate alloy, heat for 7 minutes, then cool to 1450℃, add iron, manganese, nickel-germanium and nickel-hafnium intermediate alloy, and finally add aluminum, titanium, silicon and carbon. During the whole smelting process, the electromagnetic stirring is continuously applied, the magnetic induction intensity at the center of the melt is 30mT, the electromagnetic stirring is 12 minutes, and the magnetic field direction is reversed every 2 minutes during the stirring process. After refining, the alloy liquid is poured into a high-strength graphite mold preheated to 700℃ and kept for more than 2h in a box-type resistance furnace at a pouring temperature of 1460℃, and a cylindrical as-cast billet is obtained;

[0045] High-temperature atmosphere heat treatment step:

[0046] First homogenization treatment: load the as-cast billet into the effective heating zone of the horizontal atmosphere sintering furnace, pass high-purity argon (purity ≥ 99.999%) into the furnace as protective gas, and set the gas flow to 1.0L / min, then heat from room temperature to 1250℃ at a rate of 5℃ / min, and keep the temperature for 2h after reaching the target temperature;

[0047] Second stage precision carburizing treatment: after the first stage of heat preservation, the furnace atmosphere is converted to a mixed gas composed of 1.0% methane, 0.03% silane, and the balance argon by volume, and the total flow rate of the mixed gas is set to 2.0 L / min. At the same time, the furnace temperature is raised from 1250°C to 1280°C at a rate of 5°C / min, and the carbon potential in the furnace is stably controlled at 0.95% for 5h at 1280°C;

[0048] Third stage reduction purification treatment: after the second stage of heat preservation, the furnace atmosphere is converted to a reducing mixed gas composed of 90% high-purity argon and 10% hydrogen by again switching the atmosphere, and the total flow rate of the mixed gas is set to 1.5 L / min. The furnace temperature is lowered from 1280°C to 1250°C, and the billet is heat treated at 1250°C for 1h. After the heat preservation is completed, the programmed cooling is started, and the billet is cooled to 800°C at a controlled cooling rate of 5°C / min. When the temperature reaches 800°C, the heating power is turned off, and the billet is naturally cooled to room temperature with the furnace.

[0049] Magnetic field-ladder temperature treatment step:

[0050] The billet after high-temperature atmosphere heat treatment is loaded into a specially designed longitudinal steady-state magnetic field heat treatment furnace, and the long axis direction of the billet is ensured to be consistent with the direction of the magnetic field. The magnetic field generating device is started to generate a steady-state strong magnetic field with a strength of 0.8T. In the magnetic field environment, the temperature is raised from 800°C to 970°C at a heating rate of 10°C / min, and the billet is heat treated at 970°C for 1h. After the heat preservation is completed, the temperature is slowly cooled from 970°C to 630°C at a rate of 5°C / min, and the billet is heat treated at 630°C for 2.5h. After the heat preservation is completed, all power supplies are turned off, and the billet is cooled to room temperature with the furnace under the condition of continuous application of the magnetic field.

[0051] Example 3

[0052] Alloy raw material preparation step:

[0053] The raw materials of each element are accurately weighed according to the mass percentage, and the total weight is 50kg. The specific composition is as follows: chromium 17.0%, molybdenum 6.5%, aluminum 2.3%, titanium 1.7%, iron 11.0%, manganese 0.9%, silicon 0.4%, carbon 0.07%, and the balance is nickel and unavoidable impurities. Trace elements such as rhenium 0.08%, ruthenium 0.06%, germanium 0.01%, and hafnium 0.04% are added in the form of nickel-20wt% rhenium, nickel-10wt% ruthenium, nickel-5wt% germanium, and nickel-5wt% hafnium intermediate alloys.

[0054] Melting and casting step:

[0055] Nickel, chromium and molybdenum are first added, and then the temperature is raised to 1490°C for melting, after which nickel-rhenium and nickel-ruthenium intermediate alloys are added, the temperature is maintained for 7 minutes, and then the temperature is lowered to 1460°C, iron, manganese, nickel-germanium and nickel-hafnium intermediate alloys are added, and finally aluminum, titanium, silicon and carbon are added. During the entire melting process, electromagnetic stirring is continuously applied, with a magnetic induction intensity of 30 mT at the center of the melt, and the electromagnetic stirring is performed for 12 minutes, with the magnetic field direction being reversed every 2 minutes during the stirring process. After refining is completed, the alloy liquid is poured into a high-strength graphite mold preheated to 700°C and maintained for more than 2 h in a box-type resistance furnace at a pouring temperature of 1460°C, to obtain a cylindrical as-cast billet;

[0056] High-temperature atmosphere heat treatment step:

[0057] First-stage homogenization treatment: The as-cast billet is loaded into the effective heating zone of a horizontal atmosphere sintering furnace, high-purity argon (purity ≥ 99.999%) is introduced into the furnace as a protective gas, the gas flow is set to 1.0 L / min, and then the temperature is raised from room temperature to 1150°C at a heating rate of 10°C / min. After reaching the target temperature, the temperature is maintained for 4 h;

[0058] Second-stage precision carburizing treatment: After the first-stage holding is completed, the atmosphere in the furnace is switched by an atmosphere switching system to a mixed gas composed of 2.0% by volume of methane, 0.1% by volume of silane, and the balance of argon, and the total flow rate of the mixed gas is set to 2.0 L / min. At the same time, the furnace temperature is raised from 1150°C to 1320°C at a rate of 5°C / min, and the temperature is maintained at 1320°C for 3 h, with the carbon potential in the furnace being stably controlled at 1.05%;

[0059] Third-stage reduction purification treatment: After the second-stage holding is completed, the atmosphere in the furnace is switched again to a reducing mixed gas composed of 90% high-purity argon and 10% hydrogen, and the total flow rate of the mixed gas is set to 1.5 L / min. The furnace temperature is lowered from 1320°C to 1150°C, and the temperature is maintained at 1150°C for 2 h. After the holding is completed, the programmed cooling is started, and the billet is cooled to 800°C at a controlled cooling rate of 5°C / min. After reaching 800°C, the heating power is turned off, and the billet is naturally cooled to room temperature along with the furnace;

[0060] Magnetic field-ladder temperature change treatment step:

[0061] The billet after high-temperature atmosphere heat treatment is loaded into a special longitudinal steady magnetic field heat treatment furnace, and the long axis direction of the billet is ensured to be consistent with the magnetic field direction, the magnetic field generating device is started to generate a steady strong magnetic field with a strength of 1.2T, in the magnetic field environment, the temperature is raised from 800℃ to 930℃ at a heating rate of 5℃ / min, and the temperature is kept at 930℃ for 2h, after the holding is completed, the furnace temperature is slowly cooled from 930℃ to 670℃ at a rate of 2℃ / min, and the temperature is kept at 670℃ for 1.5h, after the holding is completed, all power supplies are turned off, and the billet is cooled to room temperature in the state of continuously applied magnetic field.

[0062] Comparative Example 1

[0063] 1. Alloy raw material preparation step:

[0064] The element raw materials are accurately weighed according to the mass percentage, and the specific composition is: chromium 18.0%, molybdenum 6.0%, aluminum 2.5%, titanium 1.5%, iron 12.2%, manganese 0.8%, silicon 0.5%, carbon 0.06%, the balance is nickel and unavoidable impurities, without adding rhenium, ruthenium, germanium, hafnium intermediate alloy;

[0065] 2. Melting and casting step:

[0066] The same as Example 1;

[0067] 3. High-temperature atmosphere heat treatment step:

[0068] The same as Example 1;

[0069] 4. Magnetic field-ladder temperature treatment step:

[0070] The same as Example 1.

[0071] Comparative Example 2

[0072] 1. Alloy raw material preparation step:

[0073] The same as Example 1;

[0074] 2. Melting and casting step:

[0075] The same as Example 1;

[0076] 3. High-temperature atmosphere heat treatment step:

[0077] Only the first segment treatment is performed: high-purity argon gas (1.0L / min) is introduced, the temperature is raised from room temperature to 1200℃ at a rate of 7℃ / min, and kept at 1200℃ for 3 hours, after the holding is completed, the temperature is lowered to 800℃ at a program-controlled cooling rate of 5℃ / min, and then cooled to room temperature with the furnace, and the whole process flow of the second segment precision carburizing treatment and the third segment reducing atmosphere treatment is omitted;

[0078] 4. Magnetic field-step temperature change treatment step:

[0079] The same as Example 1.

[0080] Comparative Example 3

[0081] 1. Alloy raw material preparation step:

[0082] The same as Example 1;

[0083] 2. Melting and casting step:

[0084] The same as Example 1;

[0085] 3. High-temperature atmosphere heat treatment step:

[0086] The same as Example 1;

[0087] 4. Magnetic field-step temperature change treatment step:

[0088] The entire magnetic field-step temperature change treatment process is omitted, and the blank is used as the final sample after completing the high-temperature atmosphere heat treatment.

[0089] Performance test: the high-toughness corrosion-resistant nickel-based alloys obtained in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are subjected to performance test, and the test data obtained are recorded in the following table:

[0090]

[0091] In the performance test, the high-toughness corrosion-resistant nickel-based alloys obtained in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are tested, the impact toughness is tested according to the GB / T 229-2020 standard, the pitting corrosion performance is tested according to the GB / T 17899-2023 standard, and the uniform corrosion rate and intergranular corrosion are tested according to the GB / T 4334-2020 standard.

[0092] It can be seen that the impact toughness of the three examples is maintained at an excellent level of 145-152 J / cm 2 , the toughness of Comparative Example 1 is significantly reduced to 98 J / cm 2 due to the lack of micro-alloying elements, the reduction is 36%, and the toughness of Comparative Example 3 is reduced to 115 J / cm 2 due to the omission of magnetic field treatment, which indicates that the optimization of the crystal phase by the magnetic field and the improvement of the toughness are crucial;

[0093] The example group performs well in the pitting, uniform corrosion and intergranular corrosion tests, the pitting resistance of the comparative example 2 is the worst after omitting the carburizing treatment, and serious pitting occurs, the intergranular corrosion depth of the comparative example 1 lacking micro-alloying elements is 98.5 μm, which is 6 times higher than that of the example;

[0094] The example 1 exhibits the best toughness and corrosion resistance combination: 152 J / cm 2 The impact toughness and 0.0012 mm / a corrosion rate prove that the complete composition system and the whole process technology are indispensable for realizing the high toughness and corrosion resistance, the present application solves the technical problem that the high toughness and high corrosion resistance are difficult to be combined in the nickel-based alloy by the micro-alloying of rhenium, ruthenium, germanium and hafnium, the multi-stage heat treatment process and the magnetic field treatment, and provides an ideal material solution for the structural parts in the harsh corrosion environment.

[0095] In the description of the present specification, the description referring to the terms "one experiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the experiment or example are included in at least one experiment or example of the present application. The illustrative description of the above terms in the present specification does not necessarily refer to the same experiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more experiments or examples in a suitable manner.

[0096] The above disclosed preferred experiments of the present application are only used to help explain the present application. The preferred experiments do not describe all the details and do not limit the present application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the present specification. The present specification selects and specifically describes these experiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing a high-toughness corrosion-resistant nickel-based alloy, characterized by comprising the steps of: consists of the following ingredients by mass percentage: ​ chromium 17-19%, molybdenum 5.5-6.5%, aluminum 2.3-2.7%, titanium 1.3-1.7%, iron 11-13%, manganese 0.7-0.9%, silicon 0.4-0.6%, carbon 0.05-0.07%, rhenium 0.08-0.12%, ruthenium 0.04-0.06%, germanium 0.01-0.02%, hafnium 0.02-0.04%, the balance being nickel and inevitable impurities; The preparation method of the high-toughness corrosion-resistant nickel-based alloy comprises the following steps: (1) Preparation of raw materials: weigh each element raw material according to the mass percentage, wherein rhenium, ruthenium, germanium and hafnium are added in the form of intermediate alloy; (2) Melting and casting: place the raw materials in a vacuum induction furnace in sequence, melt under the condition of 1450-1490℃ and vacuum degree ≤5Pa, use electromagnetic stirring throughout the process, the center magnetic induction intensity of the melt is 30mT, the casting temperature is 1450-1470℃, use a mold preheated to 650-750℃, and obtain a billet; (3) High-temperature atmosphere heat treatment: place the billet into an atmosphere sintering furnace and perform the following steps in sequence; First section: under the protection of inert gas, heat from room temperature to 1150-1250℃ at a rate of 5-10℃ / min, and keep for 2-4h; Second section: perform carburizing treatment in carbon-silane coupled atmosphere at 1280-1320℃ for 3-5h, control the carbon potential to be 0.95-1.05%; Third section: switch to reducing atmosphere, keep for 1-2h at 1150-1250℃, then control cooling to below 800℃, and then cool to room temperature in the furnace to obtain a billet; (4) Magnetic field-ladder temperature treatment: place the billet after step (3) vertically along its main axis in a magnetic field heat treatment device, heat from 800℃ to 930-970℃ at a rate of 5-10℃ / min and keep for 1-2h in a longitudinal steady magnetic field environment of 0.8-1.2T, then cool to 630-670℃ at a rate of 2-5℃ / min and keep for 1.5-2.5h, and finally cool to room temperature in the furnace.

2. The method of claim 1, wherein the corrosion-resistant nickel-based alloy has high toughness. In step (1), the rhenium, ruthenium, germanium and hafnium are added in the form of nickel-20wt% rhenium, nickel-10wt% ruthenium, nickel-5wt% germanium and nickel-5wt% hafnium intermediate alloy respectively.

3. The method of claim 1, wherein the corrosion-resistant nickel-based alloy has high toughness. In step (2), the sequence is: first add nickel, chromium and molybdenum, heat to 1470-1490℃ to melt, then add nickel-rhenium and nickel-ruthenium intermediate alloy, keep for 5-10 minutes, then cool to 1450-1460℃, add iron, manganese, nickel-germanium and nickel-hafnium intermediate alloy, and finally add aluminum, titanium, silicon and carbon, electromagnetic stirring for 12 minutes, and reverse the magnetic field direction every 2 minutes during the stirring process.

4. The method of claim 1, wherein the corrosion-resistant nickel-based alloy has high toughness. In the first section of step (3), the inert gas is argon.

5. The method of claim 1, wherein the corrosion resistant nickel-based alloy has high toughness. In the second section of step (3), the carbon-silane coupled atmosphere is a mixture of methane, argon and silane, wherein the volume fraction of methane is 1.0-2.0%, the volume fraction of silane is 0.03-0.1%, and the balance is argon, and the total gas flow is 2L / min.

6. The method of claim 1, wherein the corrosion resistant nickel-based alloy has high toughness. In the third paragraph of step (3), the reducing atmosphere is a mixture of argon and hydrogen with a volume ratio of 90:10, and the gas flow rate is 1.5 L / min, followed by cooling at a rate of 5℃ / min to 800℃.

7. The method of claim 1, wherein the corrosion resistant nickel-based alloy has a high toughness. In step (4), the magnetic field heat treatment device is a magnetic field heat treatment furnace, the magnetic field source is a water-cooled copper coil electromagnet or a low-temperature superconducting magnet, the working temperature is room temperature-1200℃, the temperature can be programmed to rise and fall, the magnetic field is 0-1.2T continuously adjustable, and it is protected by an inert atmosphere.

8. A high-toughness, corrosion-resistant nickel-base alloy, characterized by: The high-toughness corrosion-resistant nickel-based alloy is prepared by the method of any one of claims 1-7.

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