Stainless Steel is a big family and wide used metal material, there are various grades in this group, these grades have special chemical composition and properties to suit various applications, two of them are remarkable grades, namely, 304 stainless steel and 316 stainless steel, the most stainless steel grades are used all over the world.
However, what is the difference between 304 and 316 stainless steel, when selecting grade 304, and when selecting grade 316? Let us find out key difference and small differences through checking these two grades.
304 Stainless Steel
304 stainless steel contains 18% chromium, 8% nickel, and other major alloying elements include small amounts of manganese, silicon and carbon, it is a typical 18/8 austenitic stainless steel grade, overall 304 presents excellent properties to meet many cases making it the most popular grade.
What make 304 so popular?
▪ Resistant to oxidation, corrosion and durability
▪ Excellent formability, fabrication and welding characteristics
▪ Relatively less expensive
316 Stainless Steel
316 stainless steel contains 16% chromium, 10% nickel, 2 to 3% molybdenum, and also contains silicon, manganese, and carbon content, it is second used grade.
316 is durable, easy-to-fabricate, clean, weld and finish grade, it is considerably more resistant to solutions of sulfuric acid, chlorides, bromides, iodides and fatty acids at high temperature, especially for chloride environment.
Of course, 304 and 316 have some same points or similar points.
▪ They are both Austenitic stainless steels, possess the similar structure.
▪ They are non-magnetic, will be a slight magnetic properties after cold working.
▪ Similar mechanical properties, like Tensile strength, Yield point, Elongation and Hardness.
▪ Both 304 and 316 can be used for general corrosion service.
What Is The Difference Between 304 And 316?
After analyzing chemical composition makeup, corrosion resistance, cost and suitable applications, the key difference between 304 and 316 stainless steel is that 316 grade has better corrosion resistance thanks to addition of molybdenum than 304, especially for chloride applications, and last longer service life. 304 grade is cost effective choice and performs well for general service, selecting which type depend on your application and environment.
Chemical Composition
Obviously, there are different chemical compositions and alloy proportions between 304 and 316, these differences make them having different functions and characteristics.
304 and 316 Chemical Compostion Comparison, max %.
|
Grade |
C |
Si |
Mn |
P |
S |
N |
Cr |
Ni |
Mo |
Iron |
|
304 |
0.08 |
1.00 |
2.00 |
0.045 |
0.030 |
0.10 |
18 – 20 |
8.0 – 10.5 |
– |
Bal. |
|
316 |
0.08 |
1.00 |
2.00 |
0.045 |
0.030 |
0.10 |
16 – 18 |
10.0 – 14.0 |
2.0 – 3.0 |
Bal. |
The key difference between 304 and 316 stainless steel in chemical composition is molybdenum element, 316 haves 2 – 3% of it, however, 304 does not have, this is the most important factor to decide their use range, both grades have similar proportion of other alloys.
Corrosion Resistance
Standard 304 grade can against corrosion attack due to high Chromium content with low carbon content, it is excellent in many corrosive media.
However, 304 has one weakness, it is subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above 60 °C (approximate).
316 has superior corrosion resistance because of the addition of molybdenum, this gives 316 ability to withstand harsh environments, especially in chloride environment, 316 possesses obvious advantage compared to 304.
Cost
Basically, the cost of stainless steel depends on the alloys that are present in their composition, 304 and 316 have similar alloy content except 316 have molybdenum added, molybdenum is more expensive alloy, this making 316 is more expensive than 304, in many cases, grade 304 is typically more affordable than grade 316.
Use Range
When selecting which type is best option for your intended use, cost and corrosion resistance requirements must be considered as presented above, it is hard to say which one is better, just depending on your application.
304 stainless steel has excellent comprehensive properties to suitable for the most applications, considering cost concern, 304 is better option for many industries, the typical applications have:
▪ Household products
▪ Auto parts
▪ Medical equipment
▪ Building materials
▪ Chemicals
▪ Food process
▪ Agriculture
▪ Ship parts
▪ Heat exchanger
316 is known as marine stainless steel, often considered one of the most suitable choices when selecting an austenitic stainless steel for sea water environments and marine applications, but we should note it is not resistant to warm sea water.
▪ Food preparation equipment particularly in chloride environments
▪ Laboratory benches & equipment
▪ Coastal architectural panelling, railings & trim
▪ Boat fittings
▪ Chemical containers, including for transport
▪ Heat Exchangers
▪ Woven or welded screens for mining, quarrying & water filtration
▪ Threaded fasteners
▪ Springs
Post time: Dec-19-2022
