Stainless steel is one of the most versatile materials, agreed? Among its many types, the two names you’ll hear most often are 304 and 18-8 stainless steel. At first glance, they seem identical, and many people assume they’re the same. But in reality, there are key differences that set them apart. This sparks the debate: 304 vs 18-8 stainless steel.
Actually, both materials share the same origin and are known for their durability. But the way each stainless steel performs in different environments varies. Are you wondering about the real difference between these two popular types? You’re in the right place! In this guide, I will compare 304 and 18-8 stainless steel head-to-head and explain their differences. So let’s begin!
Are 304 and 18-8 the Same? A Common Misconception!
It’s a widespread belief that 304 and 18-8 stainless steels are identical. However, that’s not entirely true! This confusion is due to the similar chemical composition and appearance of both stainless steel types. Both look shiny, resist rust, and are used in various daily life gadgets. However, the term “18-8 stainless steel” is actually a general category, not a specific grade.
However, the term “18-8 stainless steel” is actually a general category, not a specific grade. It simply refers to stainless steels that contain around 18% chromium and 8% nickel. These two elements are what mainly make 18-8 stainless specific. However, the content of all other alloying elements is not exact. Due to this, it becomes more general. On the other hand, 304 stainless steel is a specific grade within that 18-8 group.
It follows a defined composition standard under the AISI (American Iron and Steel Institute). Besides chromium and nickel, 304 also includes small amounts of other elements. Those extra elements have specific percentages that give stainless steel unique properties. That’s why i304 stainless is a defined grade with fixed limits on all major and minor components.
In simple words, we can say that all 304 stainless steels are 18-8, but not all 18-8 stainless steels are 304.
304 vs 18-8 Stainless Steel: Key Differences!
In the section below, I will discuss all the differences between 304 and 18-8 stainless steel.
1- Chemical composition
When comparing 304 and 18-8 stainless steel, the first difference lies in their chemical composition. As I said above, 18-8 doesn’t represent a specific grade of stainless steel. The numbers 18 and 8 give only two ingredient percentages. Those include 18% chromium and 8% nickel. In simple terms, it doesn’t precisely define the full chemical composition (trace or elements).
On the flip side, in 304 stainless, things become more specific. 304 is an exact grade defined by the American Iron and Steel Institute (AISI). It also contains about 18% chromium and 8% nickel. In addition to these two elements, 304 stainless steel also contains a small amount of other elements. Those include carbon (up to 0.08%), manganese (up to 2%), and silicon (up to 1%). You can see that the percentage content of other traces is also specific.
2- Quality Consistency
Quality consistency refers to how uniform and reliable the quality of each stainless type is. Let me explain how 304 and 18-8 stainless steels differ in this regard. If we look at 304 stainless steel, it is a specific standardized grade. It means every manufacturer has to make it with the same amount of the elements to meet quality standards. In other words, every batch of 304 stainless steel comes with equal quality.
No matter where you buy 304 stainless steel, you will get the same level of strength and quality. On the flip side, 18-8 stainless is like a family term. It includes several types of stainless steel with different compositions. Since it is a generic term, the exact mix of elements can differ slightly from one manufacturer to another. For example, some versions of 18-8 stainless steel might have a higher carbon content, while others have a lower one.
3- Mechanical Strength
Mechanical strength is another significant aspect in which 304 and 18-8 stainless steel differ. Both of these stainless steel types behave differently under pressure. For example, 304 stainless steel is a clear winner in terms of mechanical strength. WHY? The reason lies in its controlled and precise composition. Every element present in 304 stainless steel has a specific percentage content.
This means that its resistance to bending, stretching, and breaking is more consistent and defined. When you expose 304 stainless steel to different loads and pressures, it does not break easily. On the other hand, 18-8 stainless is a broad category. So the mechanical strength depends on the exact grade or the manufacturer’s preferences. Some types of 18-8 may have slightly lower tensile strength and become unstable under stress.
4- Corrosion Resistance
Stainless steel and galvanized steel are overall excellent materials for corrosion resistance. But when it comes to types, 18-8 stainless steel and 304 stainless steel resist corrosion differently. HOW? If we discuss 304 stainless steel, it is excellent at resisting corrosion. The reason is against its consistent composition. It contains an ideal amount of chromium (about 18%) and nickel (about 8%).
So when 304 stainless steel is exposed to moisture or air, it forms an oxide layer. This layer acts as a protective shield, preventing the surface from further rust. On the flip side, 18-8 stainless steel also offers good corrosion resistance due to the same main ingredients. But remember, “18-8” is a general term, not a specific formula or standard.
So manufacturers can slightly change the amount of nickel and chromium. This slight variation in nickel and chromium content can highly affect the corrosion resistance. So we can say that some versions of 18-8 stainless steel perform well, like 304, because they have equal chromium and nickel content. However, some 18-8 stainless steel can be compromised in terms of corrosion resistance.
5- Welding and Fabrication
Welding and fabrication are other factors that differentiate both 304 and 18-8 stainless steel. For example, 304 stainless is far easier to work with. WHY? The reason is that it has a controlled composition and a lower carbon content. The low carbon content means 304 stainless steel sheets are not very hard. As a result, you can easily cut, shape, and join it without losing strength.
During welding, 304 stainless steel doesn’t form cracks or weak spots easily. So, the final product will be durable and strong. On the contrary, 18-8 stainless steel can also be welded and fabricated. However, the ease of the process depends on the exact grade and amount of carbon. Some 18-8 stainless steel has higher carbon, which makes it difficult to weld and fabricate.
6- Performance Stability
Performance stability refers to how well a material maintains its performance over time. So, this is another differentiating factor between 304 and 18-8 stainless steel. For instance, 304 stainless steel offers steady performance even in changing environments. WHY? Because 304 follows a strict, standardized formula for the content of different elements. Its behavior under heat, pressure, or moisture is always predictable.
18-8 stainless steel, on the other hand, is slightly less predictable. The reason is that it is a general term that includes several grades. Each of those grades’ performances varies with different conditions. For example, one batch of 18-8 stainless steel might handle heat and chemicals very well. However, the other batch may not perform strongly due to varying composition.
7- Application Suitability
Both 304 and 18-8 stainless steel are versatile in their application. However, due to varying compositions, their usability varies across sectors. Mainly, 304 stainless steel and Hastelloy are useful where performance stability and quality are key. For example, you can find 304 stainless steel bars and coils in!
- Kitchen sinks, countertops, and appliances
- Food processing and dairy equipment
- Medical and surgical instruments
- Chemical containers and storage tanks
- Architectural panels and railings
- Outdoor furniture and decorative structures
On the reverse side, 18-8 stainless steel is generally used in less demanding applications. You can mainly use it for making!
- Bolts, nuts, and screws
- Washers and fasteners for general use
- Cookware and cutlery
- Small kitchen tools (spoons, spatulas, etc.)
- Automotive parts and fittings
- Electrical enclosures and hardware
8- Cost & Affordability
The cost difference between 304 and 18-8 stainless is the most prominent differentiating factor. If you look at the 304 stainless steel, it is slightly more expensive. But WHY? The main reason is that it is made under strict quality standards. Every batch of 304 stainless steel has the same formula for composition. It means you know exactly what you are getting.
So, you mainly pay for its guaranteed composition, consistent performance, and long-term reliability. However, due to its long-term performance, I consider it a good investment for the long run. On the other hand, 18-8 stainless is a bit cheaper. That’s because it’s a general type, not a specific grade like 304. The amount of chromium and nickel in it can vary slightly from one manufacturer to another. This reduces its production cost.
What to Look for If You Are Choosing Between 304 and 18-8 Stainless Steel
As you can see above, how 304 and 18-8 stainless steel differ in many aspects. However, if you are still confused about which one to choose, worry not! Here are the main factors to keep in mind when choosing between them!
- Consider the Environment: The environment in which you want to use stainless steel matters a lot. If your project or product will be exposed to moisture, humidity, or saltwater, then 304 stainless steel is the better choice. On the other hand, 18-8 stainless steel performs well indoors or in dry, clean environments.
- Think About the Purpose: You should also think about the purpose for which you want to use stainless steel. For heavy-duty uses like food processing, medical tools, or construction, 304 stainless steel is ideal. The reason is that it offers consistent performance. However, if you’re making everyday items like cookware, bolts, etc., 18-8 stainless steel is a wise choice.
- Check the Quality Needs: Quality needs are another factor you must consider. As I said above, 304 stainless steel is an official grade with controlled chemical composition. So, it is an ideal choice if your project requires strict quality control. 18-8 stainless steel, however, is a more general term. It does not contain an exact mix of other contents. If you do not require consistent performance, you can go for 18-8 stainless steel.
- Compare the Cost: Your budget is the ultimate criterion for choosing between 304 and 18-8 stainless steel. Suppose you don’t care about price but focus on long-term performance and quality. In that case, 304 stainless steel is costly but a reliable choice. However, 18-8 stainless steel is more budget-friendly. If you are working on a short-term project, choose 18-8 stainless steel. It can save you money without compromising performance too much.
Conclusion
Stainless steel is one of the most commonly used materials today. However, when it comes to its types, a common debate you can hear is between 304 and 18-8 stainless steel. Both of these appear similar due to their appearance and elemental composition. Therefore, many people confuse them as the same. But these stainless steel types vary in many terms, as I discussed in this article.
For example, 304 stainless steel is standardized and an official type. Its composition is particular. Due to which its performance is predictable and long-lasting. However, 18-8 stainless steel is a general term that includes various grades of stainless steel. All of them vary in composition, quality, performance, and price. I recommend evaluating your project needs and choosing the stainless steel that best suits your project.