Stainless steel AISI 904L

Stainless Steel AISI 904L – The Material for Stainless Steel Containers in Extremely Corrosive Environments

Stainless steel 1.4539, also known as AISI 904L, is a highly alloyed austenitic stainless steel alloy, particularly valued for its exceptional resistance to corrosive media and extreme environmental conditions. With its high nickel content and the addition of molybdenum and copper, AISI 904L  offers outstanding resistance to acids, chlorides, and many other aggressive substances. These properties make the material a preferred choice for the manufacture of stainless steel tanks and components in the chemical, pharmaceutical, and petrochemical industries.

This article will provide you with more information about the outstanding properties of stainless steel AISI 904 L , its advantages compared to other stainless steel alloys, and why this material is particularly suited for stainless steel tanks in corrosive environments.

What is Stainless Steel AISI 904L ? 

Stainless steel 1.4539 (AISI 904L) is a highly alloyed stainless steel alloy specifically developed for processing in particularly aggressive environments. The material consists primarily of nickel (24–26 %), chromium (19–23 %), molybdenum (4–5 %), and copper (1–2 %), which gives it exceptional corrosion resistance. Additionally, the material has a low carbon content (max. 0.02 %), which helps prevent carbide formation and increases resistance to intergranular corrosion.

The alloy is particularly known for its excellent resistance to sulfuric acid and other aggressive acids, as well as its resistance to chlorides and marine environments. Stainless steel 1.4539 is therefore ideal for manufacturing tanks, reactors, heat exchangers, and other components that come into contact with highly corrosive chemicals.

Key Features of Stainless Steel AISI 904L:

• Excellent Corrosion Resistance: The alloy provides excellent resistance to many aggressive chemicals, including sulfuric acid, hydrochloric acid, phosphoric acid, and chlorides.
• High-Temperature Resistance: Stainless steel 1.4539 remains stable at higher temperatures and resistant to oxidation and corrosion.
• Excellent Weldability: Due to its low carbon content, stainless steel 1.4539 welds exceptionally well without the risk of intergranular corrosion at the welds.
• High Strength: Stainless steel 1.4539 offers high mechanical strength and toughness, even at low temperatures and extreme environmental conditions.
• Hygienic Properties: The material has a smooth, pore-free surface that facilitates easy cleaning – a particularly important feature in the food and pharmaceutical industries.

Buying Used Equipment & Reactors in AISI 904L:

At Behälter KG, you can benefit from a range of in-stock used process equipment, tanks, and reactors made of 1.4539. A used 1.4539 process tank or storage tank is immediately available and significantly cheaper than a new purchase. This greatly reduces investment risk without compromising the quality of the material. Additionally, by purchasing a used AISI 904L  agitator or tank, you contribute to the circular economy, as no new resources are required for production in the spirit of sustainability.

The majority of our AISI 904L equipment comes from global pharmaceutical companies, where these items were sometimes purchased by us in used or unused condition. For almost all AISI 904L equipment, we provide extensive technical documentation and information about the precise last use, enabling you to quickly assess suitability for new projects. All in-stock containers and tanks can be viewed at our central warehouse in Bremen at any time.

Differences to Other Stainless Steel Alloys

Compared to other stainless steel alloys like 1.4401 (AISI 316) or 1.4571 (AISI 316Ti), stainless steel 1.4539 offers significantly higher resistance to aggressive chemicals and acids. While 1.4401 and 1.4571 are primarily used in less aggressive environments, stainless steel AISI 904L is ideal for use in highly corrosive environments, such as those in the chemical industry or the oil and gas industry, due to its high nickel and molybdenum content.

Another difference from 1.4401 and 1.4571 is the higher resistance of stainless steel 1.4539 to chloride-containing media, which makes it especially suitable for applications in marine environments or wastewater treatment.

Key Properties of Stainless Steel AISI 904L 

Stainless steel AISI 904L offers numerous outstanding properties that make it ideal for particularly demanding applications. The key features include:

1. Corrosion Resistance

The exceptional corrosion resistance of stainless steel AISI 904L is one of its most outstanding features. The material is particularly resistant to many aggressive media, including:

• Sulfuric and Other Acids: 1.4539 offers excellent resistance to highly corrosive acids such as sulfuric acid, phosphoric acid, and hydrochloric acid.
• Chlorides: Due to its high molybdenum content, stainless steel 1.4539 shows particularly high resistance to chloride-containing solutions and seawater, making it ideal for the marine sector and the chemical industry.
• Corrosion at High Temperatures: The material remains stable at temperatures up to 400°C and is resistant to oxidation and corrosion.

2. Weldability and Processing

Another outstanding feature of stainless steel AISI 904L is its excellent weldability. The low carbon content prevents carbide formation, minimizing the risk of intergranular corrosion at the welds. This makes stainless steel 1.4539 ideal for applications requiring welding, such as the construction of stainless steel tanks and pipelines.

3. High-Temperature Resistance

Another highlight of stainless steel 1.4539 is its stability at high temperatures. Even with continuous operation in hot environments, the material retains its mechanical properties and corrosion resistance, making it a preferred choice for applications in the chemical industry and in the processing of aggressive chemicals.

4. High Mechanical Strength

AISI 904L offers excellent mechanical strength and toughness, making the material particularly suitable for mechanical applications. The strength remains stable even at low temperatures, making AISI 904L suitable for use in extremely cold environments.

5. Hygienic Properties

Stainless steel 1.4539 features a smooth, pore-free surface, which is highly important for the food, pharmaceutical, and medical industries. Easy cleaning and disinfection of the surfaces are crucial for meeting the highest hygiene standards.

Applications of Stainless Steel AISI 904L 

Due to its excellent corrosion resistance and mechanical properties, stainless steel AISI 904L  is used in a variety of applications, particularly in industries dealing with aggressive chemicals and extreme environments. The main application areas include:

1. Chemical Industry

Stainless steel AISI 904L is particularly resistant to aggressive acids, especially sulfuric and phosphoric acids, and is therefore frequently used in the chemical industry for the manufacture of reactors, storage tanks, and pipelines. Its resistance to chlorides also makes it a preferred choice for wastewater treatment and chemical production.

2. Petrochemical Industry

In the petrochemical industry, stainless steel 1.4539 is used in applications where contact with highly corrosive media occurs, such as in refinery technology, oil and gas processing, and the storage and transport of chemical substances.

3. Pharmaceutical Industry

Due to its high hygiene standards and corrosion resistance, stainless steelAISI 904L is used in the pharmaceutical industry for the manufacture of equipment and tanks that come into contact with sensitive and corrosive substances.

4. Food Industry

In the food industry, stainless steel AISI 904L is used for the manufacture of containers and pipelines that come into contact with aggressive cleaning agents or salt-containing solutions. The material meets the high requirements for hygiene and corrosion resistance.