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Views: 12 Author: Wang Publish Time: 2024-07-17 Origin: Site
Stainless steel 317L is a molybdenum bearing, low carbon content “L” grade austenitic stainless steel that provides improved corrosion resistance over 304L and 316L stainless steels. The low carbon provides resistance to sensitization during welding and other thermal processes. Stainless steel grade 317L is a low carbon version of grade 317 stainless steel. It has the same high strength and corrosion resistance as 317 steel but can produce stronger welds due to the low carbon content. The alloy provides improved resistance relative to 316L in strongly corrosive environments containing sulfurous media, chlorides, and other halides.
The low carbon content of Alloy 317L enables it to be welded without intergranular corrosion resulting from chromium carbide precipitation enabling it to be used in the as-welded condition. With the addition of nitrogen as a strengthening agent, the alloy can be dual certified as Alloy 317 (UNS S31700). Due to its low carbon content, 317L also provides resistance to sensitization when welded and higher creep, stress to rupture, and tensile strength at elevated temperatures. It is non-magnetic in the annealed condition but may become slightly magnetic after welding. It cannot be hardened by heat treatment, however the material will harden due to cold working. Alloy 317L can be easily welded and processed by standard shop fabrication practices.
Alloy 317L is a molybdenum containing, low carbon austenitic stainless steel with increased additions of chromium, nickel, and molybdenum for better corrosion resistance and incrased resistance to chemical attack for sulfurous, acetic, formic, citric, and tartaric acids. Stainless steel 317L pipes manufactured by JN Alloy factory:
The composition of 317L stainless steel gives it unique properties and characteristics. This type of stainless steel is made up of a combination of elements such as chromium, nickel, molybdenum, and carbon. Chromium is the main component of 317L stainless steel, which has excellent corrosion resistance. It forms a protective layer on the surface of the metal to prevent rusting and staining. Nickel also plays an important role in providing corrosion resistance and improving high-temperature strength.
Molybdenum improves the resistance to pitting corrosion of chloride solutions commonly found in harsh environments such as seawater or chemical processing plants. Carbon content helps to increase hardness, but if not controlled properly, it can reduce weldability. In addition, there are also trace amounts of other elements such as silicon, sulfur, phosphorus, and nitrogen, which can affect specific properties such as machinability or toughness. The precise balance between these elements ensures that 317L stainless steel has superior performance to traditional austenitic grades when used in high-temperature corrosive environments. The chemical composition of grade 317L stainless steel is outlined in the following table.
Element | Content (%) |
Iron, Fe | Balance |
Chromium, Cr | 18-20 |
Nickel, Ni | 11-15 |
Molybdenum, Mo | 3-4 |
Manganese, Mn | 2 |
Silicon, Si | 1 |
Phosphorous, P | 0.045 |
Carbon, C | 0.03 |
Sulfur, S | 0.03 |
The higher molybdenum content of Alloy 317L ensures excellent overall and localized corrosion resistance in most media compared to 304/304L and 316/316L stainless steels. Environments that are not corrosive to 304/304L stainless steel will not generally corrode 317L. However, one exception is strongly oxidizing acids such as nitric acid. Alloys containing molybdenum generally do not perform well in these environments.
Alloy 317L has excellent corrosion resistance to a wide range of chemicals. It resists attack by sulfuric acid, acid chlorine and phosphoric acid. It is used to handle hot organic acids and fatty acids frequently found in food and pharmaceutical processing applications.
The corrosion resistance of 317 and 317L should be the same in any given environment. An exception is where the alloy will be exposed to chromium carbide precipitation temperatures in the range of 800 – 1500°F (427 – 816°C). Due to its low carbon content, 317L is the material of choice for preventing intergranular corrosion in this service. Generally speaking, austenitic stainless steels are prone to chloride stress corrosion cracking in halide service. Although 317L is more resistant to stress corrosion cracking than 304/304L stainless steel, it is still susceptible due to its higher molybdenum content.
The higher chromium, molybdenum and nitrogen content of 317L enhances its ability to resist pitting and crevice corrosion in the presence of chlorides and other halides. The Pitting Resistance Equivalency (PREN), which includes the Nitrogen Number (PREN), is a relative measure of pitting resistance. The chart below provides a comparison of Alloy 317L and other austenitic stainless steels.
Welding 317L stainless steel is an important consideration when using this material. One of the challenges of welding 317L is its high carbon content, which can lead to sensitization and corrosion issues if not managed properly.
To mitigate these risks, it is important to use appropriate welding techniques, such as low heat input and slow cooling rates. This will help prevent the formation of carbides, which can cause sensitization and damage the corrosion resistance of the material.
Another important consideration is the choice of filler metal. It is recommended to use low-carbon austenitic filler metals such as AWS E316L or E317L for optimal results. This will help ensure good weldability while maintaining excellent mechanical properties and corrosion resistance.
It is also worth noting that in some cases, post-weld heat treatment may be necessary to fully restore the properties of the material after welding. This may involve annealing at a temperature between 1850–2050°F followed by rapid quenching.
When using 317L stainless steel, proper welding techniques and careful selection of filler metals are critical to maintaining its unique combination of strength, toughness, and corrosion resistance.
317L stainless steel is known for its excellent corrosion resistance, making it an ideal material choice for a wide range of applications. This type of stainless steel is used in various industries, including chemical processing, oil and gas, food production, pharmaceuticals, and pulp and paper.
One of the main reasons why 317L stainless steel is favored in these industries is its high resistance to acids such as sulfuric acid. It also has excellent resistance to other irritating chemicals such as chlorides and phosphates.
In the chemical processing industry, 317L is often used in distillation columns that can withstand high temperatures and corrosive environments. Additionally, this stainless steel is used in tanks and storage containers for storing acidic liquids.
The oil and gas industry also uses 317L stainless steel because of its excellent strength at high temperatures. It is commonly used in pipelines that transport natural gas or crude oil over long distances.
Food production facilities use 317L for blenders, mixers, or storage tanks, as they require frequent cleaning with harsh detergents. The same reasoning applies to pharmaceutical plants or laboratories: they require materials that are not easily corrosive but still sufficiently hygienic, without contaminating the products being produced.
Due to the excellent combination of durability under extreme conditions and chemical stability over time, 317L stainless steel can be used in many applications, making it an important component in many different industrial processes today.
In short, 317L stainless steel is a highly corrosion-resistant material with many beneficial properties, such as high creep resistance and excellent strength even at high temperatures. Its versatility makes it popular in various industries such as chemical processing, pharmaceutical, and food processing equipment. With proper welding techniques and careful heat treatment procedures when necessary, this alloy can provide excellent performance over a long period of time without experiencing serious wear or failure issues.
If you want to find more information about stainless steel, we’d advise you to visit JN Alloy. As a leading supplier of stainless steel products across the world, JN Alloy provides customers with high-quality stainless steel products like stainless steel sheets, stainless steel bars, stainless steel pipes, stainless steel fittings, carbon steel products, and JN Alloy supports customized drawings and makes the products you need at a very competitive price!
