Stainless steel AISI 316 / 316 L

Stainless Steel 1.4401 / 1.4404 – The Material for High-Quality Stainless Steel tanks and Demanding Applications

Stainless steel 1.4401 and 1.4404 are among the most widely used austenitic stainless steel alloys and are indispensable in a wide range of industrial applications due to their excellent properties. They are colloquially referred to as V4A stainless steel. Both materials are known for their outstanding corrosion resistance, high strength, toughness, and excellent weldability. Especially in the production of stainless steel tanks used in demanding industries such as the food industry, chemical industry, and medical technology, these materials find broad application.

In this comprehensive article, we would like to delve into the properties, advantages, and versatile applications of stainless steel 1.4401 and 1.4404, and explain why these materials are the ideal choice for stainless steel tanks. Also, take a look at our article on Corrosion Resistance of Stainless Steel and our Overview of Common Materials for Stainless Steel Containers.

What is Stainless Steel 316 / 316L?

Stainless Steel 1.4401 / 1.4404 also known as AISI 316 / AISI 316L are highly alloyed, austenitic stainless steels. Both materials belong to the group of non-corrosive steels and are known for their excellent corrosion resistance and high mechanical strength. They mainly consist of iron, chromium (16-18%), nickel (10-14%), and a special addition of molybdenum (2-3%). Molybdenum is a key factor for the exceptional corrosion resistance of these alloys, as it supports the formation of a stable passive oxide film on the surface, protecting the stainless steel from aggressive chemical influences.

Key Features:

• High Corrosion Resistance: The molybdenum content effectively protects against attacks by chlorides, salts, and aggressive chemicals. This makes stainless steel 1.4401 and 1.4404 particularly suitable for container construction in the maritime industry, as well as in the chemical and pharmaceutical industries.
• Austenitic Structure: These alloys possess high toughness and do not become brittle at low temperatures. They are also non-magnetic.
• Weldability: Both materials are easily weldable and can be integrated into complex structures without difficulty, making them ideal for a wide range of industrial applications.
• Hygienic Properties: The smooth surface of stainless steel allows for easy cleaning and prevents the accumulation of bacteria and other microorganisms. This feature is particularly important in areas such as food processing and medical technology.

Depiction of a brand-new process vessel made from material 1.4404

Differences Between 1.4401 and 1.4404

Although stainless steel 1.4401 and 1.4404 essentially have the same chemical properties, there are some differences to consider when choosing the right material for specific applications:

1. Carbon Content: The carbon content of 1.4404 is lower compared to 1.4401, which improves weldability and reduces the risk of cracks at the weld seams. For heavily loaded applications or requirements for particularly good weld seam quality, 1.4404 is often the preferred choice.
2. Corrosion Resistance: Both materials offer excellent corrosion resistance, but 1.4404 offers even better resistance to intergranular corrosion, especially after welding, due to its lower carbon content and refined microstructure.
3. Mechanical Properties: Due to the lower carbon content and better weldability, 1.4404 often exhibits higher strength and toughness while offering better formability. These properties make it the preferred choice in medical technology and for critical applications where high mechanical loads may occur.

Buying Used Containers & Reactors in 1.4401 / 1.4404

At Behälter KG, you can benefit from over 300 used process kettles, tanks, vessels, and agitators made of 1.4401 / 1.4404 (V4A) that are available from stock. A used 1.4401/4 process tanks or storage tank is immediately available and significantly cheaper than a new purchase. This significantly reduces investment risk without compromising on material quality. Additionally, by purchasing a used 1.4404 agitator or tank, you contribute to the circular economy, as no new resources are needed for production.

We offer extensive technical documentation and information about the exact previous use of almost all devices made from 1.4404 or 1.4401 to quickly assess suitability for new projects. All containers and tanks in stock can be viewed at our central warehouse in Bremen at any time.

Key Properties of Stainless Steel 1.4401 / 1.4404

Stainless steel 1.4401 and 1.4404 offer a wide range of excellent mechanical and chemical properties that make them an ideal choice for many industrial applications:

1. Corrosion Resistance

One of the most important features of stainless steel 1.4401 and 1.4404 is their outstanding corrosion resistance. Thanks to the molybdenum content, these stainless steels provide excellent protection against:

• Chlorides (salts), which are particularly present in maritime environments or in the food industry
• Acids, including many organic and inorganic acids
• Alkalis and other chemically aggressive substances
• High-Temperature Corrosion, especially in environments with fluctuating temperature stress

This exceptional corrosion resistance is a key reason why stainless steel containers made of 1.4401 and 1.4404 are used in numerous demanding applications.

2. Strength and Toughness

Stainless steel 1.4401 and 1.4404 are known for their high strength and toughness. They maintain their structural integrity even at low temperatures and are highly resistant to mechanical stress. This makes them ideal for applications where both mechanical and thermal loads may occur.

3. Heat Resistance

Although stainless steel 1.4401 and 1.4404 are not suitable for continuous use at extreme temperatures (above 400°C), they offer very good resistance to short-term overheating and temperature fluctuations. This makes them an excellent choice for applications in hot environments such as food processing or chemical plants.

4. Weldability and Formability

Both materials are highly weldable, even in thin wall thicknesses. The weldability of 1.4404 is even better due to the lower carbon content. Stainless steel 1.4401 and 1.4404 can be easily integrated into complex structures and container designs without the risk of cracks or corrosion at the weld seams.

5. Hygiene and Cleanliness

Another outstanding feature of stainless steel 1.4401 and 1.4404 is their high hygiene level and easy cleanability. This is especially important in the food industry, medical technology, and pharmaceuticals. The smooth and pore-free surface prevents the accumulation of bacteria and other microorganisms, which is critical for food safety and compliance with hygiene regulations.

Applications of Stainless Steel 1.4401 / 1.4404

Stainless steel 1.4401 and 1.4404 are used in a variety of industries. Noteworthy applications include:

1. Food Industry

In the food industry, stainless steel containers made from 1.4401 and 1.4404 are crucial. They are used in a variety of applications such as storage, transportation, and processing of food. The corrosion resistance to salts, acids, and alkalis, along with hygienic properties, makes these materials ideal for producing storage tanks, kettles, silos, agitators, and other containers.

2. Chemical Industry

The chemical industry requires materials that can withstand the attacks of aggressive chemicals. Stainless steel 1.4401 and 1.4404 are the preferred choice for manufacturing pipes, reactors, storage tanks, and pressure vessels that come into contact with acids, alkalis, and other aggressive substances.

3. Medical Technology and Pharmaceuticals

Stainless steel containers made of 1.4401 and 1.4404 are indispensable in medical technology due to their excellent hygienic properties and corrosion resistance. They are used to manufacture medical devices, instruments, and for storing pharmaceutical substances and chemicals. The excellent cleanability and ability to maintain sterilization are essential in this field.

4. Water and Wastewater Treatment

Water treatment and wastewater treatment place special demands on material durability. Stainless steel 1.4401 and 1.4404 are resistant to corrosion caused by aggressive substances found in wastewater. Stainless steel containers made from these alloys are therefore often used for storing and transporting water, chemicals, and other liquids in water and wastewater treatment.