Nickel-based alloy refers to a type of alloy that has comprehensive properties such as high strength and certain resistance to oxidation and corrosion at high temperatures of 650 to 1000°C. According to the main properties, they are further 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. High-temperature alloys are divided into iron-based high-temperature alloys, nickel-based high-temperature alloys and cobalt-based high-temperature alloys according to different substrates. Among them, nickel-based high-temperature alloys are referred to as nickel-based alloys.

Origin and development 

Nickel-based alloys were developed in the late 1930s. The United Kingdom first produced the nickel-based alloy Nimonic 75 (Ni-20Cr-0.4Ti) in 1941; in order to improve the creep strength, Al was added to develop Nimonic 80 (Ni-20Cr- 2.5Ti-1.3Al); the United States in the mid-1940s, Russia in the late 1940s, and China in the mid-1950s also developed nickel-based alloys. The development of nickel-based alloys includes two aspects, namely the improvement of alloy composition and the innovation of production technology. For example, in the early 1950s, the development of vacuum smelting technology created conditions for refining nickel-based alloys containing high Al and Ti, which led to a substantial increase in alloy strength and service temperature. In the late 1950s, due to the increase in the operating temperature of turbine blades, alloys were required to have higher high-temperature strength. However, if the strength of the alloy was high, it would be difficult or even impossible to deform. Therefore, precision casting technology was used to develop a series of alloys with good high-temperature strength. of casting alloys. In the mid-1960s, directional crystallization and single crystal superalloys with better performance were developed, as well as powder metallurgy superalloys. In order to meet the needs of ships and industrial gas turbines, a number of high-Cr nickel-based alloys with good hot corrosion resistance and stable structure have been developed since the 1960s. In about 40 years from the early 1940s to the late 1970s, the operating temperature of nickel-based alloys increased from 700 to 1,100°C, an average increase of about 10°C per year. Today, the service temperature of nickel-based alloys can exceed 1,100°C. From the aforementioned Nimonic75 alloy with a simple composition, to the recently developed MA6000 alloy, the tensile strength can reach 2,220MPa and the yield strength is 192MPa at 1,100°C; Its lasting strength reaches about 1,000 hours under the condition of 1,100℃/137MPa, and it can be used in aircraft engine blades.

The effect of various metals on nickel-based alloys

For a specific nickel-based alloy, there are many variables in a specific environment, including: concentration, temperature, ventilation, liquid (gas) flow rate, impurities, abrasion, cycle process conditions, etc. These variables can create a variety of corrosion problems. The answers to these questions can be found in nickel and other alloying elements. Metallic nickel maintains an austenite, face-centered cubic structure until it reaches its melting point. This provides a degree of freedom for the ductile-brittle transition and also greatly reduces manufacturing problems that arise when other metals coexist. In the electrochemical sequence, nickel is more inert than iron and more active than copper. Therefore, in reducing environments, nickel is more resistant to corrosion than iron, but not as resistant as copper. On the basis of nickel, after adding chromium, the alloy has anti-oxidation properties, which can produce many kinds of alloys with a wide range of applications, so that they can have the best resistance to reducing environments and oxidizing environments. . Compared with stainless steel and other iron-based alloys, nickel-based alloys can accommodate more alloying elements in solid solution and maintain good metallurgical stability. These factors allow the addition of a variety of alloying elements, making nickel-based alloys widely used in widely varying corrosive environments.  

Common elements in nickel-based alloys mainly include

Nickel Ni provides metallurgical stability, improved thermal stability and weldability, improved corrosion resistance to reducing acids and caustic soda, and improved resistance to stress corrosion cracking especially in chloride and caustic soda environments.

Chromium Cr improves oxidation resistance, high-temperature oxidation resistance, and sulfur resistance, and improves pitting corrosion and crevice corrosion resistance.

Molybdenum Mo improves the corrosion resistance to reducing acids, improves the resistance to pitting corrosion and crevice corrosion in chloride-containing aqueous solution environments, and improves high-temperature strength.

Iron Fe improves resistance to high-temperature carburizing environments, reduces alloy costs, and controls thermal expansion. Copper Cu improves the corrosion resistance to reducing acids (especially sulfuric acid and hydrofluoric acid used in air-restricted situations) and salts. The addition of copper to nickel-chromium-molybdenum-iron alloy helps to improve the corrosion resistance to hydrogen fluoride. Resistance to acids, phosphoric acids and sulfuric acid.

Aluminum Al improves high temperature oxidation resistance and age hardening.

Titanium Ti is combined with carbon to reduce intergranular corrosion caused by chromium carbide precipitation during heat treatment and improve aging strengthening.

Niobium Nb is combined with carbon to reduce intergranular corrosion caused by chromium carbide precipitation during heat treatment, improve resistance to pitting corrosion and crevice corrosion, and improve high-temperature strength.

Tungsten W improves resistance to reducing acids and local corrosion, improves strength and weldability.

Nitrogen N improves metallurgical stability, resistance to pitting and crevice corrosion, and strength.

Cobalt Co provides enhanced high-temperature strength and improved resistance to carbonization and vulcanization. Many of these alloying elements can be combined with nickel in a wide composition range to form single-phase solid solutions, ensuring that the alloy has good corrosion resistance under many corrosion conditions. The alloy also has good mechanical properties in a fully annealed state without worrying about harmful metallurgical changes caused by manufacturing or thermal processing. The strength of many high-nickel alloys can be improved through solid solution hardening, carbide precipitation, precipitation (age) hardening, and dispersion strengthening.

Application areas

Nickel-based alloys are used in many fields, such as: petrochemical industry, marine ships, housing construction, aerospace, machinery manufacturing, rail transportation, military industry, power energy, telecommunications, automotive field, medical field, etc.

Market trend

1. Product structure

With the good operation of my country's macroeconomic environment and industrial development situation, various industries have received more or less corresponding impacts, and the nickel-based alloy industry is no exception. In addition, companies in the industry have continuously introduced advanced foreign production in recent years. Equipment and supporting technologies have driven the prosperity and development of the nickel-based alloy industry market. At present, there are several basic products such as alloy nickel powder, nickel alloy profiles, nickel alloy wire and nickel alloy tube.

2. Price

Price is the main consideration for nickel-based alloy companies when making strategies. Because the current nickel-based alloy industry is highly concentrated, competition is fierce. However, in the future, with the good development of my country's economic operation situation, my country's labor costs will also increase. It is rising year by year. In addition, the nickel-based alloy industry has gradually begun to develop in clusters, and has concentrated on forming upstream, mid-stream and downstream structural integrity in certain areas with well-known domestic institutions. The peripherals have increased support for the industrial system, which will eventually lead to the nickel industry. Base alloy product prices show an upward trend.

3. Channels

In the future, the marketing channels of my country's nickel-based alloy industry products are likely to expand to wide channels and long channels, strengthen close supply with upstream and downstream enterprises, and close cooperation with scientific research circles, academic institutions, etc., so as to extend the industrial chain of their own enterprises. , moving towards an integrated full industry chain model, gaining more market share for its own enterprises, and at the same time promoting the overall development of the nickel-based alloy industry.

4. Service

With the advancement of science and technology, product technology is becoming more and more complex, and consumers are becoming more and more dependent on enterprises. When they buy a product, they not only buy the product itself, but also hope to receive reliable and thoughtful service after purchasing the product. An enterprise's quality assurance, service commitment, service attitude and service efficiency have become an important condition for consumers to judge product quality and decide whether to purchase.