Nickel-based alloys with other elements are called nickel alloys. Nickel has good mechanical, physical, and chemical properties, and the added elements can improve its oxidation resistance, high-temperature resistance, high-temperature strength and improve certain physical properties. Nickel alloys can be used as materials, precision alloys (as alloys for electron tubes, resistance alloys, Electric alloys, etc.), nickel-based nickel alloys, base corrosion-resistant alloys, shape memory alloys, etc. Nickel alloys are widely used in the development, chemical, electronic precision, navigation, aviation, and aerospace sectors.
Nickel can be composed of alloys of copper, iron, manganese, chromium, silicon, and magnesium. Among them, nickel alloy is the famous Monel alloy, which has high strength and good plasticity.
1. Definition of Nickel-Based Alloys
Nickel-based alloys are generally alloyed with a nickel-based alloy content of 30wt%, and the nickel content of common products exceeds 50wt%. It seems to have superior mechanical strength and corrosion resistance at high temperatures. It is called superalloy together with iron-based and cobalt-based alloys. (Superalloys are generally used in high-temperature environments above 540°C, and according to their applications, marine alloys are designed for special environments, superalloys, and equipment with the necessary mechanical strength. , the petrochemical industry or special electronics/optoelectronics and other fields.
| Application field | product requirements | Product Usage |
| aerospace industry | Good mechanical strength at very high temperatures | Car engine, gasoline engine, engine valve |
| energy industry | Good resistance to high temperature and high temperature, high temperature, and high-temperature oxidation | Furnace workpieces, oil, and coatings, heat treatment industry, natural gas industry |
| petrochemical industry | An aqueous solution (acid, alkali, chloride ion) | The desalination plant, petrochemical seawater treatment |
| Electronics/Optoelectronics Industry General | Generally resistant to high temperature or high temperature and low-temperature environment | Shell parts, lead frames, computer battery grilles |
2. Essence and development
Nickel-based alloys are the base alloys that began to be accepted in 30 months. The United Kingdom first produced Nimonic75 (Ni-20Cr-0.4Ti) in 1 year; in order to improve the variable strength, Al was added, and Nimonic 8 (Ni-20Cr-2.5.5) Ti- 1)), the United States developed a new Russia in the 1940s, in the 1940s, and in the mid-1950s in China. innovation.
For example, in the 1950s, the vacuum refining technology created conditions for the refining of high and titanium alloys, containing both Al in the molten state and the sublimation state of the hot temperature, so that the temperature increase in the early 5000s was similar to that in the early 1960s. The improvement of the service temperature requires the alloy to have higher high-temperature strength, but the alloy will be deformed when the strength is high. Superalloys Directional Crystallization and Superalloys, and Superalloys.
In order to be compatible with industrial gas turbines, since the release of the early 1960s to the carrier-based aircraft requires high-nickel-based alloys and high-nickel-based alloys that can be developed, the working temperature of nickel has been increased from about 700 to 700 °C since the late 1970s. An average annual increase of 10 ℃. Up to now, nickel-based alloys have exceeded 1.100 °C. The initial test nickel-amine 55 alloy has been used since the alloy of about 700, and the MA6000000000 of about 700 has been used recently. Alloy, the tensile strength at 1,100℃ can be 2220mpa, 192Mpa; 1,100℃/137mpa/137mpa conditions are long-lasting and durable
3. Characteristics of Nickel-Based Alloys
Nickel-based alloys are the strongest materials in superalloys. The name superalloy is the most widely used material.
include:
(1) Superheat resistance: high temperature and high strength, as well as mechanical properties such as thermal resistance, thermal resistance, oxidation resistance, and good plasticity and corrosion resistance.
() Alloy super-solution-based alloys are often added with two kinds of nickel alloy additive elements, adding a variety of or more than ten different environments; and enhancing the corrosion resistance of solid solution environments.
(3) The working environment is super evil: Nickel-based alloys are widely used in various harsh conditions, such as high-pressure aerospace situations in flight rooms, nuclear energy, petroleum, structural parts of the marine industry, corrosion resistance, etc.
Fourth, the microstructure of nickel-based alloys
The structure of nickel is mainly a high-temperature stable element. In order to improve the alloy properties of the surface of these core modules (secondary FCC), the alloy of Ni-Wo forms various phases of elements, and the types of secondary phases to improve the form include MC, M23C6, M6C, M7C3, mainly distributed in grain boundaries, and carbon-based (coherent) structures such as γ’ or γ”. The chemical composition of γ’ and γ” phases at high temperatures is roughly Ni3 (Al, Ti) or Ni3Nb, such events are very stable, and their strengthening gives excellent results. The microstructure of a typical nickel-based alloy is shown in Figure 1:
Figure 1 Microstructure of typical nickel-based alloys
The microspheres with alloying degree improve the microstructure change with the following trends: the γ’ phase gradually increases, appears in the size, and changes from the shape to the same size, with the degree of alloying and the different morphology of the γ’ phase in addition to these, in these The alloy also appears in the process of “γ phase ++” co-formed in the γ process, and the crystals generated by discontinuous granular carbon crystallization are surrounded by crystallization, and the micro-change improves the surrounding of the thin film of the alloy. In addition, the properties of various modern nickel-based alloys are very demanding, the degree of alloying is very demanding, and the degree of alloying is very important. Harmful intermetallic phases, such as Ralph, will damage the properties and properties of the alloy.
Five, the role of alloying elements and grades
The alloy in the alloy is the highest quality alloying element and also the highest quality alloying element. And maintain the stability of the organization and the anti-plasticity of the material; while Cr, Mo, and Al have anti-oxidation and anti-oxidation effects, and have a certain strengthening effect.
(1) Solid solution elements, such as W, Mo, Co, and V, through the crystal molecular activity and the difference between the base, cause inge at the base of Ni-Fe to strengthen the material
(2) Precipitation strengthening elements such as Al, Ti, Nb, and Ta, etc., can form an integrated sequence of A3B types intermetallic sequences, such as Ni3 (Al, Ti) and other strengthening phases (γ’), so that the alloy can be effectively strengthened. , to obtain higher high-temperature strength than iron-based superalloys and cobalt-based alloys;
(3) Crystal elements, such as B, Zr strengthening, elements such as magnesium and calcium, etc., can be made of alloy superalloys. , common such as Monel 400, K-500, etc. Ni-Cr alloy, also known as Inconel, is a common nickel-based alloy, mainly used under oxidizing conditions, such as Inconel 600, 625, etc. For example, Inconel alloy is added with medium power but a large amount of Fe to nickel, the components are high temperature resistant and nickel-based alloys, used for high temperature alloying, used alloys, the price is cheap and can be used for standard devices of reaction temperature devices, such as Incoloy 800H, 825, etc. If adding reinforcement, such as Ti, Al, Nb, etc. to Inconel and Incoloy, as a precipitation element ductile (iron) nickel-based alloy, it can maintain good mechanical strength and corrosion resistance at high temperatures and is mostly used in engine injection. components, such as Inconel 718, Incoloy A-286, etc. The Ni-Cr-Mo(-W)(-Cu) alloy is called Hastelloy (Hastelloy), in which Ni-Cr-Mo is mainly used in the corrosive conditions of the pigment brand. The representative numbers of Hastelloy are C-276, C-2000, etc. Refer to Figure 2 for the main numbers and additions of nickel-based alloys:
figure 2
6. Properties of Nickel-Based Alloys
1. High temperature (instantaneous) strength
Both nickel-based alloys, it has good performance and performance (TS=1,2-1,6000; YS=900-0MPa), and this trend can be extended in Figure 3
Figure 3 The composite concept formed by the tough precipitates and ductile bases in nickel-based alloys
It can be combined with a covalent bond to form a γ’γ’γ’γ precipitation phase with a high melting point and high strength, which can be used for the ductility of the sliding system, the Wostian iron base, and the composite material. Its concept has similar excellent performance, and also has the application characteristics of the characteristic metal material base class Figure 4:
Figure 4 Strength-application temperature of various map engineering materials according to mechanical strength
2. Creep strength
Dive into the high temperature of the material (/Tm>0.5) In order to function at high temperature and produce slow plastic deformation at high temperature, the material alloy uses the best resistance to high-temperature creep and is widely used in various environments. T, used as a bearing member. The occurrence of potential changes is shown in Figure 5:
Figure 5 Three stages of creep deformation and the intensity of the effect of temperature on creep – application temperature diagram can be three stages, a latent and slow plot change in a moment (but processing deformation occurs with the increase of a certain period of time), and shortened to a point in time at the current time, called the second stage of latent change requirements, or Upcoming Four-Stage Potential Change (Secondary-State Creep or Steady), which refers to the rate of material change due to engineering processing and the potential for dynamic recovery to arrive Phenomenon, varying degrees of shrinkage increase exponentially over time, eventually reaching.
In general, varying degrees of price change increase the potential change latency and potential change.
(2) Radiation latent surface change: It is called Nabarro-herring scattered along the grain by atoms, so it is the main experience at high temperatures. The rationale for along grain boundaries is Coble Creep, at low temperatures. The smaller the grain size, the easier it is to cause significant changes in the diffusion boundary.
(3) The latent grain boundary of the material is weak, and the material is generated along the line, causing slipping along the grain boundary. Therefore, it is easier to generate small cracks at the grain boundary when the crystal is moved across the grain boundary. The upper boundary metal binder of the change-bound crystal, the metal-slip nickel-based alloy has the mesogen migration, which can generate a potential base for transient crystal shift, which can generate a potential crystal-shift crystal, which can help catalyze the precipitation of crystallization. , which can produce the basis of induced shift crystals and crystal shifts. , Ni-based alloys have superior creep resistance compared to other metal materials. Figure 6:
Figure 6 Creep properties of different alloy materials
Traditionally, crystalline forms develop in the direction of unidirectionality, and long crystalline forms develop in the direction of unidirectionality, and the altered properties grow over time, forming a potential ability to alter when resisted, so nickel Base alloys can also improve the potential to co-develop in a more effective way the changing properties of single crystal elements such as quasi-crystals, and the hidden capabilities of core-based alloys.
3. Corrosion resistance
Control of corrosion of materials is all about the best way to practice materials in industry rather than saving design. Problems such as chafing, more reducibility, etc., all require more reasonable design and important factors such as corrosion and related safety considerations. Corrosion-resistant, corrosion-resistant alloys are, as mentioned above, the corrosion-resistant nickel alloys are, as mentioned above, corrosion-resistant nickel alloys can resist corrosion; as before Corrosion-resistant alloys can resist corrosion, and corrosion-resistant alloys have the ability to resist corrosive environments; they themselves have certain corrosive environment capabilities; anti-corrosion capabilities, such as resistance to the corrosiveness of chloride ions and corrosive elements, A material with excellent ability to add matrix and nickel and matrix phase to form a solid solution, improve corrosion resistance and thermodynamic stability. If Cu, Cr, Mo, etc. are added to nickel, the corrosion resistance of the overall alloy is shown in Figure 7:
Fig.7 Schematic diagram of corrosion of different alloy materials
In addition, the alloy promotes the formation of dense products, protective films, cr2o3, al2o3, etc. oxide layers, oxide layers, oxide layers, etc., provide, provide, provide, provide, provide, provide the element that provides the material resistance or has different special concerns, especially when The requirements of the strongest alloy are the high temperature and heat resistance and the main heat resistance. When they need to be different at the same time, the properties of the alloy and the composition of the alloy elements are different. Although the high-temperature oxidation behavior of different high-temperature alloys is very complex, it is usually still composed of hydrogen oxide and oxide film. The oxidation resistance of superalloys is derived from the form of composition, and the oxidation resistance of pure nickel-based alloys is described here.
Pure nickel materials such as Ni 200/201 (UNS N02200/UNS N02201) are commercially pure nickel (>99.0%). It has good mechanical properties and excellent diamagnetic properties, as well as other physical uses, including magnetism, magnetic dimensions, high electrical conductivity, and electrical properties such as corrosion properties that require 200 nickel in applications, it requires special properties in the application performance and excellent application performance. is the main consideration and is widely used. Other uses include days as well as nickel. Base corrosion-resistant Hastelloy and Ni-Cu alloys, etc., the main alloying elements are Cr, Mo, Cu, etc., with some alloys including various acid corrosion and nickel. Corrosion resistance is comprehensively applied such as Cr-Mon-Cu; in addition, corrosion-resistant nickel-based alloys, (alloys in alloys) -Mo alloys, NiCr-Mo alloys (ie, C of corrosion), etc. The primary condition for corrosion resistance is that the combustion material that emits and burns without oxygen is a kind of high temperature, high temperature, and high-temperature resistant combustion material; nickel-chromium alloy is flammable and combustible under the conditions of nature. Oxidation and corrosion properties, vanadium, etc., when the chromium content in the alloy is greater than 13%, it will cause an effective anti-corrosion effect, while the Cr content, its corrosion resistance, but in the non-oxidizing state, such as acid, corrosion resistance, because the non-oxidizing acid catalyzes the alloy to form an oxide film, and also has an effect on the oxide film.
Adding acid and other elements to the nickel reduction alloy can reduce the corrosion resistance of nickel and copper. The nickel-molybdenum alloy is mainly used under corrosion-resistant conditions and is the best Ni-Cr-Mo(- W) The surface of the alloy has Ni-Cr and Ni-Mo alloys, mainly in oxidation and oxidation mixing containers, the alloy is used in aerosol corrosion displays, in chlorine in oxygen-containing environments and in chlorine in chlorine, and Corrosion resistant environment in choline environment. China can resist both oxidizing acids and acids, such as titanium and stainless steel, which are only resistant to oxidation. For example, Hastelloy C-276 or C-2000 alloy is a Ni-Cr-Mo alloy containing W. Figure 8:
Fig.8 Corrosion resistance data properties of different alloys reduced in acid (HCl)
Alloys with low and low carbon, generally considered to be corrosion-resistant alloys, have the best resistance to corrosion and corrosion on both sides in the moderate state of exfoliation and corrosion, as well as resistance to pitting, crevicing, and corrosion. Fluorite uses cracking energy, and these alloys are more resistant to the characteristics of precipitation because they reduce the precipitation ability of C and Si hydrocarbons. Because this type of material can be used as a product of its substance, it can be widely used in other environments. In addition, Ni-Cr-Mo-Cu alloys are resistant to nitric acid and sulfuric acid reduction, and also have good corrosion resistance in some oxidizing-mixed acids.
7. Production technology of nickel-based alloys
The traditional production process of nickel-based alloys is raw material → nickel alloy casting (melting) → secondary refining → processing → finished product → nickel downstream application Figure 9:
Fig. 9 Production flow chart of general nickel-based alloys
Other aerospace-specific applications apply special techniques such as applying unique applications. Brief introduction.
The composition of nickel-based alloys is based on the addition of materials such as Ni-Cr-Fe, such as Cu, Si, Mn, Al, Ti, Nb, W, C, and other elements. However, if we want to reorganize or add new strategies and understand their application functions in microstructures, we can use material property simulation software, and thermal and dynamic calculations of alloy systems to provide directions for optimization, which can improve the design of alloys. efficiency. The realization of alloy design must be completed by smelting technology, and the completion of nickel-based alloy melting is mainly vacuum induction melting of the electric furnace (Electric Arc Furnace, EAF) + Electro-Alag Remelting (Electro-Alag Remelting, ) and due to melting. Vacuum induction melting, VIM) partial liquid volume during smelting (more V-grade smelting, to obtain alloy steel with a higher V-smelting rate. Elements such as aluminum, and non-vacuum smelting exist in the furnace, which is more conducive to the production of slag Or mainly slag, using titanium and other smelting, or even using vacuum induction furnace smelting and vacuum consumable furnace remelting for production. Among them, VIM Figure 10:
Figure 10 Schematic diagram of vacuum melting and electroslag remelting refining equipment
The main purpose is to refine the target 7-12 alloy, remove the real impurity limit and harmful gases, and then manufacture the application control technology in some way. Inclusions, high content of leached unformed trace elements and dissolved oxygen, etc., to produce a reasonable and uniform alloy composition. R (Fig. 1) Control the casting material in a more precise way for a more precise purpose, i.e. an accurate target, with a refined refining technique, with a refined technique to remove the coarse material, the structure, and the uniformity of the structure and the microstructure Target. Usually, vacuum induction furnace refining to ensure and control the content of gas and impurities, and vacuum remelting – precision casting technology to manufacture parts. For super alloyed workpieces, the choice of refining affects impurity (that is, abnormal precipitation occurs), generally, not related to the region (such as composition and composition) and alloy technology.
It is rolled by the sandwich rolling method. To realize liquid crystal display, liquid crystal alloys make thermally ductile structures. The deformation and processing instability of the nickel-based alloy at high temperatures increase the difficulty of the nickel-based alloy manufacturing process. It is not easy, C-276 is about 2.4 times the time of stainless steel at high temperature, high temperature, and high temperature; and the high hardening rate of cold working makes its strength, strength, and cocoa 2 temperature. Different deformation and ductility occur in the area where the inclusions appear and No, not variations in purely mechanical areas or similarities in alloys)
Figure 11. The data curve of temperature elongation and deformation of nickel-based alloy Inconel 601 and 601, at 60% at low temperature, shows that cracks are likely to occur at the beginning of processing
The extended temperature range of simultaneous processing of superalloy castings allows hot processing and manufacturing. After processing or for the purpose of resisting the heat of the workpiece, heat treatment is required. The solid solution of the nickel-based alloy is based on the changes and requirements of the product (such as control, or in-process), which means giving instructions, and advice on future crystallization, pre-processing and solution, etc., Advice, as opposed to redissolving 3Cη6Cη2 to strengthen and strengthen nickel-based alloys, the heat treatment procedure is (1) reheating and dissolving to the temperature-controlled by the precipitates, (2) maintaining the temperature to reach the soluble type if its size is required, (3) cooling rate Phase M23C6 and other precipitation.
Generally speaking, the organic properties after solution treatment are affected by the grain size and intergranular precipitates. It is necessary to adjust the solution treatment and time depending on the alloy composition and the previous process to achieve the properties of the solution. When the base alloy is subjected to a thermal history of 400~800oC, chromium carbide (M23C6) precipitates out of the grain boundary, resulting in the formation of a Cr-depletion Zone around the grain boundary, which reduces the corrosion resistance of this zone, which is called sensitization. As well as the previous iron crystal system, it is easy to release the dense precipitation of the base alloy (IGA) of the (IGA). Its dissolution stage and 2) the effect stage of the γ/γ’ phase. Among them, during the solid solution production, the precipitates are redissolved in the facility, and the γ’ needs to add elements in the addition area, and at the same time obtain the phase quality of each element, and control the grain size of the main γ phase stage and the aging can maintain the temperature, cold, cold, Controlled by rapid and multi-stage aging In general, corrosion resistance and shape can be affected. physical appearance.
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