。
High-Temperature Alloys
High-Temperature alloys are special classes of alloys which are designed for applications where elevated temperature mechanical strength and high temperature corrosion resistance are required. High-Temperature alloys usually contain nickel, chromium, manganese, silicon, cobalt, and molybdenum as their principal elements. Different additional elements are blended with these elements to produce high temperature alloys with increased corrosion resistance.
Some of the common elements used to make alloys include aluminum, iron, titanium, niobium and other rare earth elements. These elements are blended together in different proportions to give the desired properties and applications. There are numerous high-temperature alloys that provide a range of options to choose from according to their specific needs. For example, there are alloys that are used in aerospace applications that require high strength and oxidation resistance. On the other hand, alloys used in chemical processing and petrochemical applications may require increased corrosion resistance.
The selection of a high-temperature alloy depends on the intended application and environment, such as temperature, pressure, and chemicals that it will come in contact with. Different alloys provide different benefits, and selecting the correct alloy that best suits the application can be challenging. One of the most important considerations is temperature: temperatures above 600°C will generally require a high-temperature alloy, as most alloys cannot maintain their mechanical strength at such a high temperature.
High-temperature alloys can be divided into two major categories: nickel-base alloys and iron-base alloys. Nickel-base alloys usually contain more than 50 percent nickel and are further divided into categories of nickel-chromium, nickel-cobalt, and nickel-iron. Nickel-chromium alloys typically contain 15 to 34 percent chromium to provide oxidation and corrosion resistance. Nickel-cobalt alloys are known to have very good strength and oxidation resistance and are used in applications that require high thermal shock resistance. Nickel-iron alloys typically have a higher melting temperature range and provide increased strength and toughness while still providing oxidation resistance.
Iron-base alloys are specifically designed to provide higher strength and creep resistance. These alloys also have relatively good corrosion resistance properties and make up a large portion of high-temperature alloys because of their lower cost. As with the nickel-base alloys, iron-base alloys can be further categorized into a few categories, such as ferritic, martensitic, austenitic, and precipitation hardening.
The selection of a high-temperature alloy depends heavily upon the intended application and environment. It is important to select the alloy that best suits the application and to determine the most suitable level of alloying elements. With the right alloy selected, it will allow for an optimal performance regarding mechanical strength and the oxidation, corrosion, and creep resistance desired. High-temperature alloys are an important class of materials used in many industries and selecting the correct one for your application will ensure the best possible results.
