As a B2B buyer, you’ve probably come across “families” and “grades” when searching for the right stainless steel for projects. There are different types and grades, all offering specific benefits. So, how do you know which one is right for your project? The five primary types of these steels are precipitation-hardened, austenitic, ferritic, martensitic, and duplex. They are all divided into many grades that dictate factors like as the material’s general quality, durability, and ability to withstand extreme temperatures.
Stainless steel is a metal alloy made primarily from iron, with at least 10.5% chromium, however not all steels are the same. It is divided into 5 common groups called austenitic, ferritic, martensitic, duplex, and precipitation-hardened. Each of these groups are divided into different grades.
To make the right choice, understanding each type’s properties is important. Let’s dive deeper into what sets them apart. Choosing the right stainless steel depends on many factors. So, what do you need to know to get the best for your project?. This article will discuss all you need to know before purchasing.
What is Stainless Steel?
Stainless steel is a metal alloy made primarily from iron, which we encounter in everyday life, but what makes it so versatile? The 10.5% chromium gives the stainless steel its unique property that makes it resistant to rust.
When chromium is exposed to oxygen, it forms a thin layer of chromium oxide on the surface, which acts as a “passive” protective layer, preventing rust and corrosion.
Stainless steel contains a minimum of 10.5% chromium, which reacts with oxygen to form a protective layer that prevents rust and corrosion.
One of the most common types is the 304. It’s popular because of its strong resistance to corrosion and overall strength. But not all stainless steel is created equal; take grade 420 for instance, which can rust when exposed to harsh chemicals.
Types and Grades of Stainless Steel
Knowing the right type of stainless steel can save you a lot of trouble in the long run. Each type has its own mix of elements and properties, which makes it good for some jobs and not for others.
The five main types of stainless steel are: austenitic, ferritic, martensitic, duplex, and precipitation-hardened. Each of these has its own strengths, depending on where and how you use it.
There are many grades for each of these categories, which affect the steel’s overall quality, durability, and ability to tolerate high temperatures. B2B buyers like myself have found it much easier to comprehend various sorts and grades and how each material should be used according to its uniqueness.
5 Types of stainless steel and their uses
I always consider a few important factors to make sure the stainless steel I choose for a project meets my objectives.
Austenitic stainless steel
So what is austenitic stainless steel?
Austenitic stainless steel is the most common type of stainless steel out there, especially for industries that need something highly resistant to corrosion. Besides being simple to deal with, it is non-magnetic, which is crucial for several applications. Because it has both nickel and chromium, it is strong and simple to weld. Austenitic stainless steel is known for its high corrosion resistance and ease of fabrication. It’s non-magnetic and comes in grades like 304 and 316.
You’ll find austenitic stainless steel in industries like food processing, chemical equipment, and even aerospace. Grades like 304 and 316 are really popular because they handle corrosion and are easy to manipulate during manufacturing.
Whenever I need stainless steel for something that’s going to see a lot of exposure to the elements, I usually opt for austenitic grades like 304 or 316.
Ferritic Stainless Steel
So what is ferritic stainless steel?
Ferritic stainless steel is magnetic and, in general, less costly due to its higher chromium content and lower nickel content. They are renowned for their ability to withstand stress corrosion and cracking, and they contain significant amounts of chromium (up to 27%). Although it is not as effective at handling stress corrosion cracking as austenitic kinds, it is nevertheless suitable for a wide range of applications and is reasonably priced. Mostly used in automotive components, kitchen appliances, industrial equipment.
Ferritic stainless steel is known for its good corrosion resistance, and it’s magnetic. You’ll find it in car parts and industrial equipment. The stainless steel grades in question are 409, 430, and 430FR. Although it is not as resilient to stress corrosion cracking as austenitic kinds but it’s still solid for many applications, especially where cost is a factor.
Martensitic Stainless Steel
So what is martensitic stainless steel?
The Martensitic stainless steel contains chromium contents ranging from 10.5% to 18%. Steels are renowned for being extremely hard and strong compared to ferritic and austenitic steels, they are less corrosion-resistant.
Strong and robust, martensitic stainless steel is commonly used for surgical instruments, cutting tools, and knives. Grades 420 and 440 have a chromium content of approximately 10.5% to 18%.
They are Cutting tools, surgical instruments, knife blades, turbine blades The grade of stainless steel that characterises this group is steel: 15-5PH, 17-4PH, 416, 420F, 420 MOD, 455, 465.
Duplex Stainless Steel
So what is duplex stainless steel?
Duplex stainless steel is like the best of both austenitic and ferritic stainless steels. it combines the toughness of ferritic stainless steel with the corrosion resistance of austenitic types.
Duplex stainless steel offers a mix of austenitic and ferritic properties, making it super resistant to stress corrosion and pitting. It’s especially good for environments where stress corrosion is a concern, like offshore oil rigs or chemical processing plants and desalination plants the different grades include S31803 and S32205.
Precipitation hardening stainless steel
This group of stainless steel contains 12% to 16% chromium and 3 to 9% nickel, comprised of durable, corrosion-resistant alloys with exceptional strength. They can be treated to yield strengths three to four times that of standard austenitic stainless steel.
Precipitation hardening stainless steel is designed to withstand extreme stress, making it perfect for aerospace, nuclear power, and other industries where strength is critical. It’s strong and resistant to both wear and corrosion, making it a high-performance choice.
They are most commonly used in the aerospace, oil and gas industries. Grades like 17-4PH and 15-5PH are known for their ability to withstand a lot of stress without breaking down.
How To Select The Right Type of Stainless Steel
When selecting on the correct stainless steel for a project, there are a few crucial variables I usually consider. Where will the steel be used, first? Will it come into contact with chemicals or water? These elements are crucial in choosing the appropriate kind.
The Process of Corrosion
When a material is going to be exposed to moisture or corrosive substances, corrosion resistance is crucial. I tend to purchase austenitic steel, especially grade 316, in humid environments because of its exceptional resistance to corrosion. If strength and hardness are more important, I choose precipitation-hardened stainless steel or martensitic stainless steel.
Cost factor: Cost is another big factor, ferritic stainless steel is typically less expensive than austenitic, so when budget constraints are tight, this might be a good choice, as long as the environment isn’t too harsh.
Magnetic Response Some types of stainless steel are more magnetic than others. Adding chromium to an alloy tends to make it more magnetic, but adding nickel offsets or even eliminates the magnetism. If I need non-magnetic steel, I go with grades like 316 or 310. But if I need magnetic properties, I look out for the 400 series, which is generally more magnetic.
What Are the Common Grades of Stainless Steel?
Understanding stainless steel grades can sometimes feel overwhelming, but it’s important because each grade brings something unique to the table.
304-grade stainless steel
This kind of stainless steel is the most popular and extensively utilized. By mass, it has about 8–10.5% nickel and 18–20% chromium. I frequently use especially when the material will come into contact with fresh water, chemicals, or food.
316-grade stainless steel
The second most popular type of stainless steel, 316, is another one I encourage B2B buyers to purchase. The 316 grade is useful in settings like food manufacturing where salt is involved. In fact, some of the cleanroom furniture and equipment I’ve seen, like the Hygienox range, are made using 316 stainless steel for its superior protection.
Conclusion
Selecting the best stainless steel (austenitic, ferritic, martensitic, duplex, and precipitation-hardened) for your requirements requires an understanding of its various varieties. The secret to making sure you buy the right quality of stainless steel that can withstand the right environmental conditions depends on your supplier. If you’re ever unsure which grade is the right fit for your project, I always recommend reaching out to us for more information. It’s better to have the right material for the job.