In this article we discuss 18-8 vs 316 grade of stainless steel. Follow along to learn about their corrosion strength, applications, and mechanical properties. Many buyers even ask if 18-8 steel is bad or good. Don’t worry, this comprehensive guide will clarify that too.
What is 18-8 Stainless Steel?
Let’s find out the chemical composition of 18-8 steel and what makes it different from other grades.
Definition and Composition of 18-8 Stainless Steel
18-8 stainless steel is another way of saying 304 SS alloy. But in the past, it was an umbrella term for steels made up of 18% Chromium and 8% Nickel. That is why, till today, you will find many websites calling 316 or 301 “18-8” stainless steel equivalents.
For the sake of this guide, anywhere you see 18-8, we are specifically referring to the 304 alloy of stainless steel. Back on track, 18-8 or 304 is a stainless alloy that offers some of the best corrosion properties on the market. Due to its chemical composition, 304 finds extensive use in appliances that come in contact with moisture and chemicals.
18-8 vs 304: Are They the Same?
18-8 is originally a broad term for stainless steels that contain 18% Chromium and 8% Nickel. So yes, 304 is technically a member of the 18-8 family. But the terminology has evolved in the past decade. So much so that when you ask for 18-8, most suppliers will provide 304 alloy.
18-8 or 18-10 Stainless Steel, Which Performs Better?
Which is better18-8 or 18-10 SS? 18-10 SS contains 10% Nickel, offering better resistance to stains, rust, and corrosion. This makes 18-10 the superior choice for food processing appliances and non-toxic cookware. 18-10 also exhibits slightly enhanced hardness.
18-8 Stainless Steel Equivalent Grades
Standards that correspond with 304 stainless steel include
- American – AISI 304
- Chinese – 0Cr18Ni9
- British – BS EN 10088 standard 1.4301
- Japanese – SUS 304
- German – Werkstoff Nr. 1.4301
What is 316 Stainless Steel?
Here, you learn about 18-8 vs 316 and how the latter stands out as an engineering metal.
Definition and Composition of 316 Stainless Steel
316 is the name given to Molybdenum-enhanced 304. By improving pitting and corrosion strength, Molybdenum makes your alloy suitable for a wide range of corrosive envirnoments.
Role of Molybdenum in 18-8 vs 316 Corrosion Resistance
When you add molybdenum to 304 steel, it produces a metal with increased resistance to salt pitting and harsh chlorides.
Composition Comparison of 18-8 vs 316
These are the elements that make up 304 and 316 stainless steels.
Elemental Breakdown (Table Format)
| Property / Element | 18-8 (≈304 SS) | 316 SS |
| Chromium (Cr) | Min 18% | Min 16% |
| Nickel (Ni) | Min 8% | Min 10% |
| Molybdenum (Mo) | – | Min 2% |
| Yield Strength | Min 205 MPa | Min 290 MPa |
| Tensile Strength | Min 505 MPa | Min 515 MPa |
Key Differences in Nickel and Molybdenum Content
304 and 316 alloys are formed by alloying stainless steels with Chromium and Nickel. However, 316 also contains Molybdenum, which makes it less vulnerable to pollutants and factory chlorides. 316 also contains a higher concentration (10 to 14%) of Nickel compared to 304 (8 to 10%).
Impact of Composition on 18-8 vs 316 Strength
304 and 316 stainless steels have high iron content, making them durable and extremely resistant to wear. If you want to compare 18-8 vs 316 in terms of strength, both alloys are nearly identical.
However, 316 is known to exhibit slightly higher strength, especially when the metal is kept at room and elevated temperatures. In addition, you can cold work both alloys to enhance their strength and hardness values considerably.
18-8 vs 316 Corrosion Resistance
18-8 vs 316 corrosion resistance, which is superior?
18-8 Stainless Steel in Everyday Environments
Due to its anti-corrosive properties, 304 alloy is a popular choice in everyday applications. These range from cookware to nuts and bolts, heat exchangers, food production equipment, and refrigerators.
Will 18-8 Stainless Steel Rust?
Yes, 304 stainless steel can rust, despite being highly resistant to corrosion. 304 will not rust in a dry environment. It is more likely to develop rust after prolonged exposure to chlorides such as salt, rain, and harsh chemical compounds. So the answer to, will 18-8 stainless steel rust is yes.
Does 18/8 Stainless Steel Rust in Saltwater?
When it comes to corrosion resistance, 304 steel is one of the best metals you can lay your hands on. Its chemical composition protects it against many kinds of atmospheric damage, from air to moisture and welding corrosion.
However, 304 is held back by its poor resistance to chloride corrosion, particularly in harsh saltwater environments. Therefore, If you are an engineering marine applications, it is better to pick 316 SS. This grade withstands saltwater and chlorides better.
316 Stainless Steel in Marine and Factory Applications
The most used stainless steel in marine and chemical processing factories is SS 316. The relatively high concentration of 316 prevents salt water from causing localized pitting or rust.
Direct Comparison: 18-8 vs 316 Corrosion Resistance
The shared characterstic between 304 and 316 SS is their strength against moisture and pollutants. The former finds extensive use in food processing, cookware, and industrial manufacturing.
Meanwhile, 316 steel, which contains molybdenum and nickel, is known to withstand harsher environments. Therefore, it is an optimal choice for marine fittings to cookware, medical implants, architectural paneling, and chemical processing equipment.
Magnetic Properties of 18-8 vs 316
If steels contain iron, doesn’t that mean all alloys of stainless steel are magnetic? The answer is not a simple yes-or-no. Some families of SS are ferromagnetic, while others are not.
18-8 vs 316 magnetic properties are determined by the alloying elements involved. For instance, a basic stainless steel, formed by adding chromium, is ferritic. Meanwhile, carbon-hardened steel exhibits martensite.
Finally, all 300-family stainless steels are austenitic. These grades contain nickel and a higher Chromium concentration. It is nickel that alters basic SS alloy into austenite, making it non-ferromagnetic. For a deeper understanding, you can check the guide on magnetism states.
Is 18/8 Stainless Steel Magnetic?
Is 18-8 stainless steel magnetic? Even though 304 is an iron alloy, the high levels of austenite cause the steel to exhibit poor magnetism in its purest form.
18-8 vs 316 Magnetic Behavior
The same rules go for molybdenum-enhanced 316 stainless steel. Despite being an alloy of iron, the high levels of austenite cause it to be non-magnetic.
Can Cold Working Cause Austenitic Stainless Steels to be Magnetic
304, 316 and other austensitic alloys of stainless steel obtain temporary magnetism through work-hardening. This process alters the microstructure of some metals, changing non-magnetic austenite into martensite.
Strength and Mechanical Properties of 18-8 vs 316
The previous section unpacked the magnetic properties of 304 and 316 stainless steels. This section will compare their strength and mechanical properties.
18-8 vs 316 Tensile Strength
The tensile strength of pure 304 SS alloy is superior to that of 316, ranging from 580 to 1180 MPa. 316 alloy exhibts an average tensile strength of 520 to 1180 MPa. Therefore, 18-8 vs 316 yield strength is settled in favor of pure 304 alloy.
18-8 vs 316 Yield Strength
In terms of yield strength, 304 and 316 alloys are nearly identical. Based on data from Makeitfrom.com, 304 has a minimum yield strength of 230 MPa that goes up to 860 MPa. Meanwhile, 316 has a base yield strength of 230 MPa, which goes up to 850 MPa.
Comparing Overall 18-8 vs 316 Strength
18-8 vs 316, which is generally stronger? 316 exhibits higher strength than 304 owing to its molybdenum content. However, both options possess exceptional strength, leading to high performance in a wide number of applications. 304 is also more ductile, making it suitable for stamping, bending, and deep drawing procedures
18-8 Stainless Steel vs Grade 8 Fasteners
Truth be told, there is little difference in 18-8 vs grade 8 alloy fasteners when it comes to strength and hardness. The primary difference is that 316 contains extra Molybdenum, making it less susceptiable to corrosion.
Choosing Between 18-8 vs 316 Bolt Options
Additionally, in the 18-8 vs 316 bolt conversions, 304 bolts tend to offer awesome general-purpose strength and corrosion resistance. Meanwhile, 316 is what you should choose for environments that are too harsh for 304.
CNC Performance: 18-8 vs 316 machinability
If you compare 18-8 vs 316 machinability, 304 SS comes out on top. Due to the molybdenum content in 316, it is slightly harder to machine than 304. Adding to that, 304 boasts a machinability rating of 70 on the AISI scale, while 316 scores 60.
To achieve a superior surface finish, 316 alloy also requires adjustments that 304 does not. For instance, you must reduce cutting speeds and increase force to keep the material from chipping. Not only is 304 easier to machine, but it is also easier to clean and handle.
Work hardening and tool wear
The molybdenum and nickel content give 316 a tendency to work-harden during high-speed CNC machining. This means the more you machine it, the more it becomes resistant to cutting.
Tool wear is another area where 304 alloy outshines 316. Grade 316 is not just harder to machine, but it also needs special tools to cut. This explains why 304 is preferred for precise fasteners and fittings. Meanwhile, 316 is reserved for applications that other Stainless Steel grades cannot withstand.
18-8 vs 316 galling: which performs better?
Both 304 and 316 are austenitic and therefore prone to galling under load, especially when stainless steel is run against stainless steel. Although the molybdenum content in 316 does not give it an advantage in this respect, galling resistance in 18-8 vs 316 is practically the same.
18-8 vs 316 vs 410 Stainless Steel
In this section, we discuss grade 18-8 vs 316 vs 410 SS to see how they compare.
Overview of 410 Stainless Steel
410 is an alloy stainless steel that is favored for its hardness and fair corrosion strength. It is typically composed of 13% Chromium and 0.5% nickel. As well as trace concentrations of silicon, carbon, and manganese. However, the composition varies based on the intended appliance.
Strength Comparison: 18-8 vs 316 vs 410
410 alloy technically offers higher strength than 304 and 316 stainless steels due to composition differences between 400 and 300 grade steels.
Corrosion Resistance Trade-Offs
410 stainless steel is less corrosion-resistant than 316 or 304. This is because it contains a smaller concentration of Chromium and Nickel. However, 410 is superior to both alloys strength-wise. 410 alloy also provides exceptional formability at elevated temperatures.
Choosing the Right Grade for Your Application
If you have a tough time choosing between 304, 410, and 316, consider the requirements of your application carefully. If your appliance will come in contact with saltwater or harsh chemicals, 316 is the way to go.
In contrast, 304 emerges as a suitable and economical choice for general-purpose appliances that won’t be exposed to chlorides. Meanwhile, 410 stainless is the superior choice in applications where tensile or shear strength is a factor.
Cost and Availability of 18-8 vs 316
Here, we compare the cost and availability of 304 and 316 SS alloys.
Why 18-8 Stainless Steel is More Affordable
If we are simply comparing raw materials, 316 alloy is more expensive than 304. The reason is simple. 316 is basically the same metal as 304, but with Molybdenum added.
Why 316 Stainless Steel Costs More
Material cost is the primary reason 316 SS costs more than 304 SS. When choosing between these alloys, remeber to factor in the extra cost of Molybdenum.
Market Availability of 18-8 vs 316
304 alloy is the most widely available stainless steel, making it a popular choice in everyday applications. However, that is not to say 316 is scarce. Far from it. The two alloys are readily available, but 316 will be easiest to purchase.
Is 18-8 Stainless Steel Good or Bad for Buyers?
Is 18-8 stainless steel good or bad? This is a question we’ve been getting all week, and we would love to clarify it now. As you learned before, 304 steel alloy is one of the most versatile metals you can lay your hands on. Especially when you are working with general-purpose applications.
However, for our customers who work with highly corrosive elements, it is recommended to use 316. Just think about the cost savings you stand to gain from appliances with built-in resistance to rust and chlorides.
Applications of 18-8 vs 316
Both 304 and 316 steels are versatile. In this section, you discover their applications.
Common Applications of 18-8 Stainless Steel
Examples of 304 appliances are:
- Screws, bolts, and nuts
- Cookware and kitchenware
- Heat exchangers
- Architectural paneling
Common Applications of 316 Stainless Steel
Img5_316 Stainless Steel products
316 Stainless steel is favored for a wide number of heavy-duty applications. These include
- Paper processing
- Oil pipes
- Cookware
- Food processing
- Chemical factories
- Marine fittings and more.
Cookware Comparison: Which is Better, 188 or 1810 Stainless Steel?
Which is bette,r 18-8 or 18-10 steel for cookware? The answer is simple. Grade 304 stainless steel is the superior choice for everyday cookware. It offers excellent corrosion resistance while being extremely easy to shape and cut. 316 is also a suitable alloy for this service, but it is more expensive than 316.
Industrial and Marine Hardware: 18-8 vs 316
316 stainless steel performs better in seawater and industrial environments. The reason is simple. 304 contains Molybdenum, which enhances the corrosion strength of Chromium and Nickel.
Conclusion
Are you comparing 18-8 and 18-10 stainless steel for your project? 18-8 offers great resistance against moisture and pollutants. But 316 contains Molybdenum, increasing its performance in harsh saltwater or chloride environments. Consult JieJia CNC if you are still unsure which alloy suits your application best.
FAQs:
Is 18/8 Stainless Steel Susceptible to Rust?
Despite being exceptionally corrosion-resistant, 304 SS will develop rust after prolonged exposure to chlorides or moisture. If you are building an appliance for factory or marine use, it is recommended to use Molybdenum 316 SS instead.
Is 18/8 Stainless Steel Magnetic?
SS 304, in its pure form, is austenitic; therefore, it will not stick to a magnet. Just take note that work hardening can cause 304 to shift into martensite, giving it partial or temporary magnetism.
Which is Stronger: 18-8 vs 316 Strength?
304 offers excellent corrosion strength due to its Chromium and Nickel content. But 304 can be enhanced with Molybdenum to produce 316. 316 offers even better resistance to chlorides and harsh chemical environments.
What’s the Difference Between 18-8 vs 316 Bolt Options?
304 offers excellent corrosion strength due to its Chromium and Nickel content. But if your appliance is frequently exposed to chlorides, Molybdenum-enhanced 316 is the better option.
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