Stainless Steel 317/317H

Products Description

Alloy 317L (UNS S31703) is a molybdenum-bearing austenitic stainless steel that exhibits significantly improved resistance to chemical attack compared to conventional chromium-nickel austenitic stainless steels like Alloy 304.In addition to its superior corrosion resistance, Alloy 317L offers higher creep, stress-to-rupture, and tensile strength at elevated temperatures when compared to conventional stainless steels. This makes it suitable for applications that require high strength and resistance to deformation under high-temperature conditions.The "L" in Alloy 317L signifies its low carbon content, which provides resistance to sensitization during welding and other thermal processes. Sensitization refers to the formation of chromium carbides at grain boundaries, which can result in intergranular corrosion and reduced corrosion resistance. The low carbon content of Alloy 317L helps prevent sensitization, making it suitable for welding and other thermal operations without the risk of intergranular corrosion.

General Properties

Alloy 317L (UNS S31703) is a low-carbon corrosion-resistant austenitic stainless steel that contains chromium, nickel, and molybdenum. The high levels of these alloying elements provide superior chloride pitting and general corrosion resistance compared to conventional grades such as 304/304L and 316/316L.Alloy 317L exhibits improved resistance relative to 316L in strongly corrosive environments containing sulfurous media, chlorides, and other halides.The low carbon content of Alloy 317L allows it to be welded without the risk of intergranular corrosion caused by chromium carbide precipitation. This makes it suitable for use in the as-welded condition. Additionally, the alloy can be dual certified as Alloy 317 (UNS S31700) by the addition of nitrogen as a strengthening agent.In the annealed condition, Alloy 317L is non-magnetic. It cannot be hardened by heat treatment, but it can undergo hardening through cold working. The alloy is easily weldable and can be processed using standard shop fabrication practices.Alloy 317L is a versatile material that offers excellent corrosion resistance in a variety of corrosive environments, particularly those containing chlorides and other halides. Its low carbon content and added nitrogen provide additional benefits in terms of weldability and resistance to intergranular corrosion.When selecting Alloy 317L, it's important to consider the specific application and environment to ensure optimal performance and corrosion resistance.

Corrosion Resistance

Alloy 317L, with its higher molybdenum content, offers superior general and localized corrosion resistance compared to 304/304L and 316/316L stainless steels in most media. Environments that are non-corrosive to 304/304L stainless steel will typically not corrode Alloy 317L. However, one exception to this is strongly oxidizing acids like nitric acid, where alloys containing molybdenum do not perform as well.Alloy 317L exhibits excellent corrosion resistance to a wide range of chemicals. It resists attack in sulfuric acid, acidic chlorine, and phosphoric acid. This makes it suitable for handling hot organic and fatty acids commonly found in food and pharmaceutical processing applications.The corrosion resistance of Alloy 317 and 317L is generally the same in any given environment. The only exception is when the alloy is exposed to temperatures within the range of chromium carbide precipitation (800 – 1500°F or 427 – 816°C). Due to its low carbon content, 317L is preferred in such applications to guard against intergranular corrosion.While austenitic stainless steels are susceptible to chloride stress corrosion cracking in halide service, Alloy 317L shows somewhat better resistance compared to 304/304L stainless steels due to its higher molybdenum content. However, it is still susceptible to this type of corrosion. The higher chromium, molybdenum, and nitrogen content of Alloy 317L enhance its ability to resist pitting and crevice corrosion in the presence of chlorides and other halides. The Pitting Resistance Equivalent including Nitrogen (PREN) number is a relative measure of pitting resistance. A comparison chart can provide insights into the relative performance of Alloy 317L and other austenitic stainless steels in terms of PREN.

Chemical Analysis

Weight % (all values are maximum unless a range is otherwise indicated)

Mechanical Properties

Values at 68°F (20°C) (minimum values, unless specified)