Requirements for stainless steel material

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Requirements for stainless steel: Both 321 and 304 belong to the 300 series of stainless steels, and they differ little in terms of corrosion resistance. However, in high-temperature industrial applications ranging from 500 to 600 degrees, material 321 is mostly used. Moreover, a heat-resistant steel specifically developed abroad exists, called 321H. Its carbon content is slightly higher than that of 321 material, and is similar to that of 1Cr18Ni9Ti in China. Adding an appropriate amount of Ti to stainless steel is intended to improve its resistance to intergranular corrosion. This is because in the early stages of stainless steel production, due to limited smelting technology, it was not possible to reduce the carbon content in the steel; therefore, other elements had to be added to achieve this goal. With technological advancements, low-carbon and ultra-low-carbon stainless steel grades can now be produced; as a result, 304 material is widely used. It is at this point that the heat resistance characteristics of 321, 321H, or 1Cr18Ni9Ti become apparent. 321 should be 0Cr18Ni10Ti; 321 is 304 with Ti added to improve resistance to intergranular corrosion. 304 is a general-purpose stainless steel that is widely used in manufacturing equipment and components that require good overall properties (corrosion resistance and formability). 301 stainless steel exhibits significant work hardening upon deformation, and is used in various applications that require high strength. 302 stainless steel is essentially a variant of 304 stainless steel with a higher carbon content; cold rolling can be used to impart greater strength to it. 302B is a stainless steel with a high silicon content, and it possesses excellent resistance to high-temperature oxidation. 303 and 303Se are free-cutting stainless steels containing sulfur and selenium respectively, used in applications where free-cutting properties and high surface finish are primarily required. 303Se stainless steel is also used to manufacture components that require hot heading, as it exhibits good hot workability under such conditions. 304L is a variant of 304 stainless steel with a lower carbon content, used in applications that require welding. The lower carbon content minimizes the precipitation of carbides in the heat-affected zone near the weld, and the precipitation of carbides can cause intergranular corrosion (weld erosion) in stainless steel under certain conditions. 304N is a nitrogen-containing stainless steel; nitrogen is added to enhance the strength of the steel. Stainless steels 305 and 384 contain higher levels of nickel, have a low rate of work hardening, and are suitable for various applications that require good cold formability. 308 stainless steel is used to make welding electrodes. Stainless steels 309, 310, 314, and 330 have relatively high nickel and chromium contents, which is intended to enhance the steel’s oxidation resistance and creep strength at high temperatures. 30S5 and 310S are variants of 309 and 310 stainless steels; the only difference is that they have a lower carbon content, which serves to minimize the formation of carbides in the area near the weld. Stainless steel 330 possesses particularly high resistance to carburization and thermal shock. Stainless steels 316 and 317 contain aluminum, which gives them significantly better resistance to pitting corrosion in marine and chemical industry environments compared to stainless steel 304. Among them, type 316 stainless steel has variants including low-carbon stainless steel 316L, high-strength nitrogen-containing stainless steel 316N, and free-cutting stainless steel 316F with a higher sulfur content. 321, 347, and 348 are stainless steels based on titanium, niobium plus tantalum, and niobium-stabilized respectively, and are suitable as welded components for use at high temperatures. 348 is a stainless steel suitable for the nuclear power industry, with certain restrictions on the combined content of tantalum and tungsten. There are a wide variety of stainless steels, each with distinct properties. Based on their microstructure, they can be classified into austenitic stainless steels, austenitic-ferritic stainless steels, ferritic stainless steels, martensitic stainless steels, and precipitation-hardening stainless steels, among others. Chromium is the most essential element that gives stainless steel its corrosion resistance; the chromium content is generally above 13%, with some grades having as much as 30%. Nickel is also a major alloying element in stainless steel, with concentrations that can reach around 20%. Nickel helps to achieve a single austenitic structure in stainless steel, thereby improving its corrosion resistance and toughness. In addition, some stainless steels also contain other elements such as molybdenum, vanadium, copper, manganese, and nitrogen. Stainless steel is mainly used to manufacture chemical equipment, medical devices, food industry equipment, and other components that require corrosion resistance. Stainless steel is not completely rust-proof; it just rusts more slowly. Acid-resistant steel, too, cannot resist the corrosion of all acids, but it exhibits greater resistance to corrosion in certain acids. For example, chromium stainless steel can resist corrosion by highly oxidizing acids, but it is not resistant to non-oxidizing acids; for instance, in hot hydrochloric acid, it corrodes even more slowly than ordinary carbon steel. Therefore, it should be selected appropriately based on the usage requirements. Using stainless steel is not the only way to address corrosion. (Austenitic stainless steels) mainly include: 321, (1Cr18Ni9Ti), also known as 18-8; 304, (0Cr18Ni9); 304L, (00Cr19Ni10); 306, (0Cr17Ni12Mo2); 316L, (00Cr17Ni14Mo2); and Mo2Ti. The main differences are as follows: 321 contains titanium, 316 contains molybdenum, 304 contains neither titanium nor molybdenum, while Mo2Ti contains both molybdenum and titanium. 316L has the best properties, followed by 321/304. Stainless steels 316 and 317 (the properties of 317 stainless steel are listed later) are types of stainless steels that contain molybdenum. The molybdenum content in 317 stainless steel is slightly higher than that in 316 stainless steel. Thanks to the molybdenum present in it, this grade of steel exhibits superior performance compared to 310 and 304 stainless steels. Under high-temperature conditions, when the concentration of sulfuric acid is below 15% or above 85%, 316 stainless steel has a wide range of applications. 316 stainless steel also has good resistance to chloride corrosion, which is why it is commonly used in marine environments. The maximum carbon content of 316L stainless steel is 0.03; it can be used in applications where annealing is not possible after welding and where maximum corrosion resistance is required ； Its corrosion resistance is superior to that of 304 stainless steel, offering excellent corrosion resistance during the pulp and paper production process. Moreover, 316 stainless steel is also resistant to corrosion by marine and aggressive industrial atmospheres. Heat resistance: 316 stainless steel exhibits good oxidation resistance when used intermittently at temperatures below 1600 degrees, as well as when used continuously at temperatures below 1700 degrees. Within the range of 800–1575 degrees, it is not advisable to expose 316 stainless steel to such conditions continuously; however, when used continuously outside this temperature range, 316 stainless steel exhibits good heat resistance. 316L stainless steel has better resistance to carbide precipitation than 316 stainless steel, and can be used within the aforementioned temperature range. Heat treatment involves annealing at temperatures between 1850 and 2050 degrees, followed by rapid annealing and then quick cooling. 316 stainless steel cannot be hardened by heat treatment. 316 stainless steel has good weldability. All standard welding methods can be used for welding. During welding, stainless steel filler rods or electrodes such as 316Cb, 316L, or 309Cb can be used depending on the application. To achieve the best corrosion resistance, the welded joint of 316 stainless steel requires post-weld annealing. If 316L stainless steel is used, no post-weld annealing is required. When operating in humid atmospheric and seawater environments, titanium alloys exhibit significantly better corrosion resistance than stainless steel; they are particularly resistant to pitting corrosion, acid corrosion, and stress corrosion. They also show excellent corrosion resistance to alkalis, chlorides, organic chlorine compounds, nitric acid, sulfuric acid, and other substances. ... LCB low-temperature carbon steel – this material is primarily used in environments with temperatures ranging from -45°C to 345°C, for applications involving air, hydrocarbons, non-corrosive liquids and gases, as well as saturated steam and superheated steam. Standard numbers for cast steel: ASTM A352 gr.LCB (American standard), DIN 17 245-1.1138 (German standard), AFNOR FB-M (French standard), BS 1504-161 (British standard), JIS SCPL 1 (Japanese standard). Common trade names: GS-CK24. CF8 and CF8M are stainless steel casting materials specified in ASTM A351; LCB is a carbon steel casting material specified in ASTM A352