Nickel-based alloy

With the continuous advancement of technology, stainless steel is being used more and more widely. However, in some special and harsh environments (such as oceans, nuclear power, aviation, energy, petrochemicals, food, etc.), ordinary stainless steel is no longer competent. In these special fields, special stainless steel is indispensable and irreplaceable. In recent years, with the rapid development of the economy and the continuous improvement of the level of the industrial field, more and more projects need stainless steel with better performance, and nickel-based alloys are one of the representative steel types.

Nickel-based alloys are generally defined asNiMore than30%Alloys, common productsNiThe content is more than50%, due to its super high temperature mechanical strength and corrosion resistance, it is collectively called superalloy with iron-based and cobalt-based alloys.(Superalloy), suitable for540High temperature environments above ℃, special corrosion-resistant environments, equipment that require high temperature mechanical strength is often used in aerospace, energy, petrochemical industry or special electronics/Optoelectronics and other fields.

Nickel-based alloy is30It began to be developed in the late 2018, and was1941The first nickel-based alloy is produced in the yearNimonic75(Ni-20Cr-0.4Ti,UNS N06075); in order to increase the latent change intensity, addAl, developedNimonic 80(Ni-20Cr- 2.5Ti-1.3Al,UNS N07080); Subsequently, the United States, Russia and China also successively developed nickel-based alloys. The development of nickel-based alloys includes two aspects, namely, the improvement of alloy components and the innovation of production technology. like50In the early years, the development of vacuum smelting technology was to refine high contentAlandTiThe nickel-based alloy creates conditions, driving a significant increase in alloy strength and operating temperature.50In the late years, due to the increase in the working temperature of the turbine blades, the alloy was required to have higher high-temperature strength, but when the alloy has a high strength, it is difficult to deform, or even unable to deform. Therefore, a series of casting alloys with good high-temperature strength were developed using precision casting technology.60Directional crystalline and single crystal high-temperature alloys with better performance, as well as powder metallurgy high-temperature alloys, were developed in the mid-year period.

To meet the needs of ships and industrial gas turbines,60Since the age, a number of high-quality thermal corrosion resistance and stable tissue have been developed.CrNickel-based alloy. From40The early years have arrived70About the end of the year40During the period of year, the working temperature of the nickel-based alloy is from700℃ increased to1100℃, average annual increase10About ℃. To this day, the use temperature of nickel-based alloys can exceed1100℃.

Nickel-based alloys are the most widely used and most powerful materials among super alloys, with the following characteristics:①Excellent performance: high strength can be maintained at high temperatures, and has excellent mechanical properties such as latent deformation and fatigue resistance, as well as oxidation and corrosion resistance, and good plasticity and welding properties. ② Extremely complicated alloy addition: nickel-based alloys often add more than ten alloy elements to enhance corrosion resistance in different environments; as well as solid solution strengthening or precipitation strengthening and other effects. ③The working environment is extremely harsh: nickel-based alloys are widely used in various rigorous usage conditions, such as the high-temperature and high-pressure parts of the gas chamber of the aerospace flight engine, nuclear energy, petroleum, marine industry structural parts, corrosion-resistant pipelines, etc.

According to the main properties, nickel-based alloys are divided into: nickel-based heat-resistant alloys, nickel-based corrosion-resistant alloys, nickel-based wear-resistant alloys, nickel-based precision alloys, and nickel-based shape memory alloys;

1. Nickel-based corrosion-resistant alloy. Common high corrosion resistant alloys are:Hastelloy C-276,Monel 400 Alloy,Inconel 718,Inconel 725wait

Hastelloy C-276 AIloyforNi-Cr-MoAlloys have excellent corrosion resistance under oxidative and reducing environments, and this alloy reducesC,SiThe content controls the temperature of the heat-receiving part to suppress the precipitation of carbides in the heat-affected area, and improves corrosion resistance. Based on this characteristic, it is widely used in harsh environments such as chemical equipment, and is especially suitable for inorganic and organic acids with high temperatures and mixed with impurities.(Such as formic acid and acetic acid), use in seawater corrosion environments.

Monel 400 AlloyDepend onNiandCuThe alloy consists ofCuprecious metal properties andNiIt has good corrosion resistance, excellent corrosion resistance in hydrofluoric acid and fluorine gas media, excellent corrosion resistance to hot concentrated alkali liquid, and also resistance to corrosion of neutral solutions, seawater and organic compounds. And an important feature of this alloy is that it generally does not produce stress corrosion cracks and has good cutting performance. Therefore, it is widely used in seawater desalination devices, heat exchangers, marine structure surface materials, etc.

Common chemical compositions of nickel-based alloys

Chemical composition of common nickel-based alloys

2. Nickel-based heat-resistant alloy. Common high heat resistant alloys are:Incoloy 800 Alloy,Incoloy 600 Alloywait.

Incoloy 800 Alloy(UNS N08800) is a high nickel heat-resistant steel, with good strength, corrosion resistance and oxidation resistance under high temperature environments. The composition structure is close to that of austenitic stainless steel. Widely used in overlying electric heater outer sleeves, thermocouple protection tubes, heat treatment furnaces, and use in high temperature environments.

Inconel 600 AlloyYes include14~17%CrThe nickel-based alloy has excellent oxidation resistance at high temperatures and excellent corrosion resistance to various acid and alkali environments. It is a high-end heat-resistant alloy. Suitable for various high-temperature operating conditions, such as heat exchangers, nuclear reactors, catalytic regenerators in petrochemicals, etc.

3. Precision alloy.NAS 36(Invar 36,UNS K93600)yes36Ni-FeAlloy, in-250℃ and+200It has extremely low thermal expansion coefficient between ℃, good plasticity and toughness, and is widely used as a low expansion material. Especially suitable for high-precision and high-precision machines that need to avoid thinning of size and shape due to thermal expansion.

In recent years, the global nickel-based alloy production has continued to increase, especially the demand for nickel-based alloys used in petrochemicals, energy and aerospace fields has increased the most significantly, among which the Asian market has grown the fastest. With the rapid development of the economy, nickel alloys will maintain strong demand.