About Us
We are a global metalworking including metal finish and metal products. Not only do we offer materials, but we also provide overall services for projects, from design to engineering, fabrication, and installation.
Get a free quote
DISCOVER THE AESTHETIC OF METAL
Stainless steel is primarily composed of iron alloyed with chromium, which gives it its characteristic shine and protection against rusting. Its applications range from shipment and medical to construction and aerospace. Due to containing Iron, is stainless steel magnetic? In this article, Topson will explain the magnet of stainless steel in terms of physics.
Table of Contents
Before understanding why any stainless steel has magnetism and others without, we must delve into the principle that produces magnetism. Atoms are the building blocks of matter and consist of protons (positively charged), neutrons (neutral), and electrons (negatively charged). In non-magnetic materials like most stainless steel forms, electrons exist in pairs with opposite spins that cancel out any overall magnetic effect.
Is Stainless Steel Magnetic
Is stainless steel magnetic? Most people think stainless steel is magnetic because it contains iron elements. Well, it depends! It is wrong to blindly think that stainless steel with iron is magnetic. Some types of stainless steel are magnetic, and others aren’t. For stainless steel to be magnetic, whether or not it requires further processing, certain requirements must be met:
· The alloy must contain iron.
· The alloy must have a crystal structure that is either martensitic or ferritic.
Want to learn more about stainless steel types? Please browse our blog “Something About Stainless Steel You Must Know.”
Which Types of Stainless Steel Is Magnetic
Which types of stainless steel are magnetic? In most cases, stainless steel varieties with iron in their composition are magnetic. If the alloy has an austenitic crystal structure, it’s not magnetic. Stainless steel is usually divided into martensitic, ferritic, and austenitic varieties. Among them, ferritic and martensitic stainless steel are magnetic. Some of the typical magnetic stainless steels include:
· Grades 409, 430, and 439
· Grades 410, 420, and 440
Ferritic stainless steel
Ferritic stainless steel is mainly made of iron and other elements. Unlike austenitic stainless steel, ferritic stainless steel is characterized by its body-centered cubic (BCC) crystal structure, which gives it a magnet. Virtually, ferritic stainless steel appears in various industries as a multifunctional material.
The body-centered cubic crystal structure means an atom is at the center with 8 atoms surrounding it. It looks like a cube. Its packing efficiency is about 68%, meaning that atoms occupy 68% of the volume, and the remaining 32% is space.
(Right is the BCC crystal structure picture.)
Ferritic stainless steel is divided into five categories: Class 1 to Class 3 are standard grades, and Class 4 and 5 are special steels.
Class 1 (Type 409 or 410L)
Stainless steels with the lowest chromium content are best suited for use in environments with no or slight corrosion and where slight local rusting is permitted, such as buses, coaches, and LCD frames.
Class 2 (Type 430)
Its performance is similar to 304, and it can replace 304 stainless steel when used indoors. Typical uses include washing machine rollers, indoor panels, dishwashers, etc.
Class 3 (Type 430Ti, 439, 441)
This grade type has good weldability and formability, and its performance is better than 304 stainless steel. It is commonly used in sinks, heat exchange pipes (sugar industry, energy, etc.), automotive exhaust systems (longer than 409 life), and washing machine welding parts.
Class 4 (Type 434, 436, 444)
This grade increases corrosion resistance by adding molybdenum. The corrosion resistance of 444 steel is equivalent to that of 316. This type of stainless steel is commonly used in hot water tanks, solar water heaters, automotive exhaust systems, electric heating POTS and microwave oven components, automotive trim strips, and outdoor panels.
Class 5 (Type 446, 445/447)
These grades improve corrosion resistance and oxidation resistance by adding more chromium and containing molybdenum. In marine applications, this kind of stainless steel’s corrosion and oxidation resistance are better than those of 316. The corrosion resistance of JIS 447 is comparable to that of titanium.
Martensitic stainless steel
Martensitic stainless steel is a type of stainless steel known for its high strength, hardness, and moderate corrosion resistance. It is characterized by its martensitic crystal structure, which is formed through a specific heat treatment process. The standard grades of martensitic stainless steel are 410, 420, and 440. Stainless steel grade 410 has excellent corrosion resistance and mechanical properties and is often used in cutlery, valves, and pumps. Grade 420 offers higher hardness and is commonly applied in surgical instruments, cutlery, and tools. Grade 440 stainless steel is used in applications requiring high wear resistance, such as bearings and knife blades.
Why Is Magnetism of Stainless Steel Important
Magnetism plays a crucial role in the world of stainless steel. One key reason magnetism is important in stainless steel is for sorting and identification. Magnetic properties can help differentiate between various grades of stainless steel, making it easier to sort and categorize them accurately.
In addition, magnetism can also indicate the presence of ferrite in stainless steel. Ferrite is a magnetic phase that provides strength and corrosion resistance to the material. By identifying the ferrite content level through its magnetic properties, manufacturers can ensure they use the appropriate grade for their specific needs.
Furthermore, magnetism allows for efficient assembly processes in automotive manufacturing or electronics industries. Magnetized tools or fixtures can securely hold magnetic stainless steel components during production or assembly, simplifying operations and improving productivity.
Conclusion
Stainless steel is a versatile and widely used material in various industries. While it is not inherently magnetic, certain types of stainless steel can exhibit magnetic properties depending on their composition. The most common type that is magnetic is the 400 series stainless steel. When purchasing stainless steel products or materials, it is crucial to consider your specific needs and requirements. Whether you need a non-magnetic or a magnetic grade will depend on factors such as durability, corrosion resistance, and the intended use.
Leave A Comment