Many people are surprised to learn that not all types of steel are magnetic. In fact, some steels do not stick to magnets at all. This property is particularly valuable in industries such as marine engineering, food processing, medical equipment, and electronics, where magnetic interference or contamination must be avoided.
So, what kind of steel does not stick to a magnet? The answer lies in its internal structure and chemical composition. In this article, we’ll explain why certain steels are nonmagnetic, which grades are best, and how to select the right material for your application. As a trusted stainless steel supplier, SAKYSTEEL offers a complete range of nonmagnetic stainless steels designed to deliver performance, reliability, and corrosion resistance worldwide.
To understand which steel does not stick to a magnet, we first need to understand why most steels are magnetic.
Steel is primarily made of iron, which is naturally magnetic because of its body-centered cubic (BCC) crystal structure that allows magnetic domains to align easily.
However, when nickel or other alloying elements are added, the crystal structure changes to a face-centered cubic (FCC) form, which does not allow magnetic alignment. This is the structure found in austenitic stainless steels, which are the primary nonmagnetic types of steel.
There are three main categories of stainless steels based on their crystal structure and magnetic behavior:
Austenitic Stainless Steels (Nonmagnetic):
Have an FCC structure and high nickel content, making them nonmagnetic even at low temperatures.
Ferritic Stainless Steels (Magnetic):
Have a BCC structure and contain chromium but little or no nickel, making them strongly magnetic.
Martensitic Stainless Steels (Magnetic):
Contain high carbon and chromium, are heat-treatable, and exhibit strong magnetic properties.
Therefore, austenitic stainless steels are the steels that do not stick to a magnet in their annealed condition.
The most common stainless steel in the world, 304 contains approximately 18% chromium and 8% nickel.
Its structure is fully austenitic and therefore nonmagnetic. However, after cold working or welding, it may develop a slight magnetic response due to partial transformation into martensite.
Applications: Kitchen equipment, tanks, pipes, and architectural structures.
Known as the “marine grade,” 316 stainless steel contains 16–18% chromium, 10–14% nickel, and 2–3% molybdenum. The molybdenum addition enhances corrosion resistance, especially against chlorides and saltwater. It remains nonmagnetic even after forming or machining, making it ideal for environments where magnetic interference must be avoided.
Applications: Marine hardware, chemical processing equipment, and medical tools.
This heat-resistant stainless steel, containing 25% chromium and 20% nickel, offers both high-temperature strength and nonmagnetic characteristics.
Applications: Furnaces, burners, and heat exchangers.
Stabilized with titanium, 321 stainless steel maintains its nonmagnetic structure even after welding, making it a great choice for aerospace and high-temperature chemical applications.
Applications: Exhaust manifolds, jet engine components, and chemical plants.
A premium super-austenitic stainless steel with very high nickel (24–26%) and molybdenum (4–5%) content, plus small additions of copper for improved acid resistance.
It is completely nonmagnetic, even after extensive forming or welding operations.
Applications: Offshore platforms, pharmaceutical equipment, chemical reactors, and luxury products.
Austenitic stainless steels are stabilized by nickel, which modifies the iron structure from BCC (magnetic) to FCC (nonmagnetic).
The FCC structure does not allow the alignment of magnetic domains, which prevents the steel from sticking to magnets.
Additionally, elements like nitrogen and manganese can further stabilize this nonmagnetic structure. That’s why grades such as 316 and 904L, which have higher nickel and molybdenum content, remain completely nonmagnetic even after heavy fabrication.
Nonmagnetic steels are critical for MRI scanners, surgical instruments, and hospital furniture, where even a small amount of magnetism can cause interference or safety hazards.
In seawater or brine environments, nonmagnetic grades like 316 and 904L provide excellent resistance to corrosion and avoid magnetically attracting debris or rust particles.
Nonmagnetic stainless steel ensures hygiene, corrosion resistance, and prevents metal contamination from magnetic fields during production.
Nonmagnetic properties prevent signal distortion, ensuring accuracy in navigation systems, sensors, and precision instruments.
In chemical reactors and pipelines where corrosion resistance and purity are essential, nonmagnetic stainless steels perform reliably under harsh conditions.
A simple magnet test can reveal the difference:
No attraction: Fully nonmagnetic (austenitic).
Slight attraction: Partial transformation due to cold work or welding.
Strong attraction: Magnetic (ferritic or martensitic).
For industrial verification, magnetic permeability can be measured using advanced equipment to confirm if the material meets specifications for nonmagnetic performance.
| Property | Nonmagnetic Steel (Austenitic) | Magnetic Steel (Ferritic/Martensitic) |
|---|---|---|
| Crystal Structure | Face-Centered Cubic (FCC) | Body-Centered Cubic (BCC) |
| Magnetic Behavior | Nonmagnetic | Strongly Magnetic |
| Nickel Content | High (8–25%) | Low or None |
| Corrosion Resistance | Excellent | Moderate to Good |
| Workability | Excellent | Limited |
| Common Grades | 304, 316, 321, 310, 904L | 409, 410, 430 |
This comparison clearly shows that steels that do not stick to magnets are those with high nickel content and an austenitic structure.
While several austenitic grades are nonmagnetic, 316L and 904L are widely regarded as the best options for critical applications.
Low carbon version of 316, offering improved weldability.
Excellent corrosion resistance in seawater and chemical environments.
Nonmagnetic even after forming and welding.
Ideal for: Marine, chemical, and medical industries.
Super austenitic grade with extremely high nickel and molybdenum content.
Maintains nonmagnetic properties even under heavy stress or cold work.
Superior resistance to acids, chlorides, and high temperatures.
Ideal for: Offshore platforms, pharmaceutical plants, and luxury industries.
To ensure the steel does not become magnetic:
Avoid excessive cold working (bending, rolling).
Use low-heat input during welding to reduce ferrite formation.
Choose high-nickel grades like 904L when strict nonmagnetism is required.
Anneal after fabrication to restore the austenitic structure.
Proper handling and processing are key to preserving the nonmagnetic nature of stainless steels.
SAKYSTEEL is a leading manufacturer and exporter of stainless steels for demanding applications requiring nonmagnetic properties.
With years of metallurgical expertise, advanced production facilities, and global supply capability, SAKYSTEEL ensures every batch meets international quality standards.
Our Advantages:
Wide range of nonmagnetic grades: 304, 316L, 321, 310, 904L.
Full compliance with ASTM, ASME, EN, and ISO standards.
Certificates available: EN 10204 3.1 / 3.2.
Professional technical support for alloy selection and fabrication.
Global logistics network ensuring fast and reliable delivery.
From marine components to precision instruments, SAKYSTEEL provides tailored stainless steel solutions that perform under the toughest conditions.
Not all steels are magnetic — only those with an austenitic crystal structure are truly nonmagnetic. Grades like 304, 316L, and 904L stand out for their superior corrosion resistance and complete nonmagnetic behavior. Among these, 316L is ideal for marine and industrial applications, while 904L offers the highest level of performance in aggressive chemical and offshore environments.
If your project demands a steel that does not stick to a magnet, choose austenitic stainless steels from SAKYSTEEL — engineered for precision, durability, and reliability in every environment.