SS 317L

SS 317L

SS 317L is a high-alloy austenitic stainless steel that is designed to provide improved resistance to corrosion in harsh environments compared to regular stainless steels. The addition of molybdenum (Mo) enhances its resistance to pitting, crevice corrosion, and stress corrosion cracking, especially in environments containing chlorides. This makes it ideal for applications where exposure to aggressive chemicals and high temperatures is a concern.

Chemical Composition of SS 317L

The chemical composition of SS 317L is as follows:

        Chromium (Cr)       18.0–20.0%
        Nickel (Ni)         11.0–14.0%
        Molybdenum (Mo)     3.0–4.0%
        Manganese (Mn)      2.0% max
        Silicon (Si)        1.0% max
        Carbon (C)          0.03% max
        Phosphorus (P)      0.045% max
        Sulfur (S)          0.03% max
        Iron (Fe)           Balance
    

The higher levels of chromium, nickel, and molybdenum in SS 317L give it excellent corrosion resistance, particularly in chloride-containing environments and high-temperature conditions.

Mechanical Properties of SS 317L

SS 317L provides excellent mechanical properties such as high strength, toughness, and formability. Below are the key mechanical properties:

• Tensile Strength: 70,000–85,000 psi (485–585 MPa)
• Yield Strength: 25,000–35,000 psi (170–240 MPa)
• Elongation: 35% in 8 inches (200 mm)
• Hardness: 130–170 Brinell
• Modulus of Elasticity: 28,000 ksi (193 GPa)

Key Properties of SS 317L

• Corrosion Resistance: SS 317L is highly resistant to **pitting**, **crevice corrosion**, and **stress corrosion cracking**. It performs excellently in chloride environments, such as in marine applications and chemical processing.
• Heat Resistance: SS 317L maintains its corrosion resistance and strength at elevated temperatures, up to around 870°C (1600°F). It is ideal for **high-temperature** applications, including heat exchangers, furnace parts, and industrial reactors.
• Weldability: SS 317L exhibits good weldability, and it can be welded using various methods such as TIG, MIG, and SMAW. It is also resistant to **sensitization** during welding, making it suitable for highly corrosive environments.
• Formability: The material is easy to form and shape, which allows it to be used in various industries for the manufacture of components such as pipes, tanks, and pressure vessels.

Applications of SS 317L

SS 317L is widely used in applications where both **corrosion resistance** and **strength** are essential. Some of the key industries and applications include:

• Chemical Processing: Used in environments where exposure to **chlorides**, **sulfuric acid**, **phosphoric acid**, and other corrosive chemicals is common.
• Marine Industry: Marine and offshore applications, particularly in the **construction of vessels**, **piping systems**, and **heat exchangers** exposed to seawater.
• Food and Pharmaceutical Industries: **Sterilizers**, **heat exchangers**, and **reactors** used in food and pharmaceutical manufacturing, where corrosion resistance is critical for maintaining hygiene and process integrity.
• Pulp and Paper Industry: Equipment exposed to bleaching agents, which can be corrosive, benefits from SS 317L's enhanced resistance to such chemicals.
• Power Generation: Boiler tubing, reactor parts, and other components that are exposed to high temperatures and aggressive fluids.
• Aerospace and Automotive: Exhaust systems, turbine parts, and other high-temperature applications in aerospace and automotive industries.

SS 317L vs SS 304L and SS 316L Comparison

SS 317L offers superior corrosion resistance compared to both SS 304L and SS 316L, especially in chloride environments. Below is a comparison of key properties:

Property	SS 317L	SS 304L	SS 316L
Chromium Content	18.0–20.0%	18.0–20.0%	16.0–18.0%
Nickel Content	11.0–14.0%	8.0–10.5%	10.0–14.0%
Molybdenum Content	3.0–4.0%	0%	2.0–3.0%
Tensile Strength	70,000–85,000 psi (485–585 MPa)	70,000 psi (485 MPa)	70,000–100,000 psi (485–690 MPa)
Corrosion Resistance	Excellent, superior in chloride environments	Good, susceptible to pitting in chlorides	Excellent, but less resistant than 317L

Standard Specifications for SS 317L

SS 317L conforms to the following recognized international standards:

• ASTM A240 - Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications.
• ASTM A312 - Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes.
• EN 10088-2 - Stainless Steels – Part 2: Technical Delivery Conditions for Sheet/Plate and Strip of Corrosion-Resistant Steels for General Purposes.
• DIN 1.4438 - German standard for SS 317L, commonly used in corrosive environments.
• JIS G4305 - Japanese standard for cold-rolled stainless steel plate, sheet, and strip.