Introduction to S32615 Acid-Resistant High-Silicon Stainless Steel

S32615 (also known as F63) is a high-performance austenitic stainless steel. Its excellent corrosion resistance, high-temperature resistance, and superior mechanical properties make it a core material in chemical, petroleum, and marine engineering fields. It is an ideal choice for manufacturing chemical containers, reactors, pipelines, and other equipment.

 

S32615 belongs to the high-silicon austenitic stainless steel category. By optimizing the ratio of elements such as chromium, nickel, molybdenum, and copper, it achieves a balance of performance in strong acid, high chloride ion, and high-temperature environments. Its austenitic crystal structure endows the material with non-magnetic characteristics, while also possessing high toughness and fatigue resistance, making it suitable for complex working conditions requiring long-term service.

 

US Designation and Standards: In US standards, its UNS designation is S32615, and its ASTM designation is F63. The relevant standard is ASTM A182/A182M-2018, "Forged or rolled alloy steel and stainless steel flanges, forged pipe fittings, valves and components for high-temperature applications." Additionally, standards such as ASTM A240/A240M, "Chromium and chromium-nickel stainless steel plates, sheets and strips for pressure vessels and general purposes," also provide some specifications.

 

Chinese grades and standards: Currently, China does not have completely corresponding standard grades. However, general standards for duplex stainless steel can be referenced, such as GB/T 3280-2015 "Cold-rolled stainless steel plates and strips" and GB/T 4237-2015 "Hot-rolled stainless steel plates and strips." In actual production and applications, performance and quality can be controlled according to these standards.

EU Grade and Standard: In EU standards, the corresponding grade is 1.4501, and the relevant standard is EN 10088-2 "Stainless Steel - Part 2: Technical conditions for delivery of general purpose flooring, sheet and strip," which specifies its chemical composition, mechanical properties, and other requirements.

 

 

1. S32615 Chemical Composition:

High Silicon (4.8–6.0%): Significantly improves resistance to corrosion from concentrated sulfuric acid and nitric acid, especially in chemical equipment.

Chromium (16.5–19.5%) and Molybdenum (0.3–1.5%): Synergistically form a dense passivation film, resisting chloride ion pitting and crevice corrosion, suitable for seawater environments.

Nickel (19–22%): Stabilizes the austenitic phase, enhancing low-temperature toughness and high-temperature strength.

Copper (1.5–2.5%): Improves corrosion resistance in acidic media, especially in sulfur-containing petroleum environments.

Low Carbon (≤0.07%): Reduces the risk of intergranular corrosion and ensures welding safety.

 

2. Mechanical Properties

Tensile Strength: 620–830 MPa; Yield Strength: ≥205 MPa;

Elongation: ≥40%; Hardness: HB ≤187;

High Temperature Performance: Maintains high strength and toughness at 1000℃, with excellent creep resistance, suitable for high-temperature equipment such as boilers and heat exchangers.

 

3. Welding Performance:

Applicable Processes: TIG, MIG, and other gas-shielded welding;

Pretreatment: Preheat to 150–200℃; Post-heat treatment: Aging at 750–800℃ to reduce the risk of intergranular corrosion in the weld zone.

 

4. Heat Treatment Process:

The heat treatment process has a significant impact on the properties of S32615. Solution treatment is the most commonly used heat treatment method, usually carried out between 1050 and 1150 degrees Celsius, followed by rapid cooling to retain the austenitic structure. This treatment eliminates work-hardening effects, restoring the material's corrosion resistance and ductility.

 

5. Scope of Application

Strong Acid Resistance: Exhibits excellent resistance to concentrated sulfuric acid (≥90%), nitric acid, and mixed acids; suitable for chemical reactors, storage tanks, seamless pipes, plates, and forgings.

 

With the development of industrial technology, the requirements for material performance are constantly increasing, and high-performance stainless steels like S32615 have broad application prospects. Through continuous process optimization and the application of new technologies, its performance can be further improved. In practical engineering applications, correct material selection, reasonable design, and standardized construction and installation are crucial to ensuring the long-term stable operation of equipment.