Since both are stainless steels, but what are the differences between them? It is a common question asked by many people, and the differences between stainless steel in one grade and another one are easy to be ignored. In this article, we will discuss the differences between Stainless Steel 304 and 316, and which is the best choice for your applications.
What is 316 Stainless Steel?
Stainless Steel 316 (or normally called as SUS316 / SS316) is a well-known alloy of stainless steel with a melting range of 2,500°F – 2,550°F (converted into °C: 1,371°C – 1,399°C).
As an austenitic stainless steel alloy, it has excellence such as high strength, corrosion resistance, and high concentrations of chromium and nickel. This alloy has a tensile strength of 579MPa (84 ksi) and the maximum use temperature of 1,472F (800˚C).
Additionally, in Stainless Steel 316 formulation, it has been added molybdenum to improve its alloy’s resistance to acids, alkalis, and chloride pitting.
Properties of 316 Stainless Steel
Stainless Steel 316 is similar to 304 Stainless Steel in terms of commonality. We are hardly to see the difference beween these two stainless steel with the naked eye due to the similar physical and mechanical properties.
The main differentiator is in the Stainless Steel 316 material composition:
- 16% of Chromium
- 10% of Nickel
- 2% of Molybdenum
The reason that makes Stainless Steel 316 more expensive than Stainless Steel 304 is due to the increase of Nickel content and the inclusion of Molybdenum.
However, Stainless Steel 316 proves superior is its increased corrosion resistance, which particularly against chlorides and chlorinated solutions.
Hence, this makes the Stainless Steel 316 more desirable for applications where exposure to salt or other powerful corrosives is an issue.
Applications of 316 Stainless Steel
The most common applications for Stainless Steel 316 are :
- Stainless Steel Baskets
- Marine Parts
- Outdoor Electrical Enclosures
- Medical-surgical instruments
- Pharmaceutical Equipment
- Chemical Equipment
What is 304 Stainless Steel?
On the other hand, Stainless Steel 304 is a durable material in terms of tensile strength, durability, corrosion and oxidation resistance.
The melting point of Stainless Steel 304 is reached at temperatures between 2,550°F – 2,650°F (converted into°C: 1,399°C – 1454°C). However, the more tensile strength it loses when the more Stainless Steel 304 reaches its melting point.
Stainless Steel 304 is especially exceptional for its high tensile strength of about 621MPa (90 ksi). This material has a maximum operating temperature of about 870°C.
Properties of 304 Stainless Steel
Stainless Steel 304 is excellence in corrosion resistance due to its high percentage of chromium. Its chemical composition consists of
- 18% of Chromium
- 8% of Nickel
- There are small amounts of Carbon & Manganese present at times also. These elements make it resistant to oxidation, which makes for easy cleaning and sanitization.
One of the weaknesses that exist in Stainless Steel 304 is its susceptibility to pitting, localized areas of corrosion, due to exposure to high chloride solutions or saline environments.
It is said that as little as 225ppm of chlorides can cause pitting corrosion to begin.
Applications of 304 Stainless Steel
The most common applications for Stainless Steel 304 are
- Auto Moldings and Trim
- Wheel Covers
- Storage Tanks
- Electrical Enclosures
- Kitchen Equipment and Appliances
Comparison between 316 and 304 Stainless Steel
|Stainless Steel 304||Stainless Steel 316|
Table 1 : Chemical Composition of 304 Stainless Steel and 316 Stainless Steel
The most significant diffence between Stainless Steel 304 and Stainless Steel 316 is that 316 tends to have more Nickel and little of Molybdenum in the mix.
The general Mechanical Properties of these two materials are mostly comparable.
The increased Nickel content and the inclusion of Molybdenum enables Stainless Steel 316 to have better chemical resistance than Stainless Steel 304. It can resist acids and chlorides, including salt, makes Stainless Steel 316 ideal for chemical processing and marine applications.
However, Stainless Steel 316 is more expensive than Stainless Steel 304 due to the additional of Nickel and Molybdenum.
Furthermore, the melting point of Stainless Steel 304 is slightly higher than Stainless Steel 316.
Stainless Steel 316 has better resistance to chemicals and chlorides than Stainless Steel 304 although Stainless Steel 304 has a higher melting point.
Why Choose 316 Stainless Steel?
i. Corrosion Resistant Properties
Stainless Steel 316 is more corrosion resistant than similar alloys, such as Stainless Steel 304 due to the addition of Molybdenum.
This reduces pitting from chemical environments and allows Stainless Steel 316 to be used in highly acidic and caustic environments that would otherwise eat away at the metal.
For example, Stainless Steel 316 can withstand caustic solutions and corrosive applications such as vapor degreasing or other parts cleaning processes.
Due to these properties, Stainless Steel 316 ideal for pharmaceutical and medical applications.
ii. Marine Applications
Seawater and salt air can damage the metals. Salt will compromise the protective oxide layer of Stainless Steel 304, causing rusting.
Hence, for marine applications, or any involving chlorides, Stainless Steel 316 is more ideal.
iii. Lasting Durability
Stainless Steel 316 is both tough and versatile, which makes it ideal for custom wire baskets built to last for years of use.
Stainless Steel 316 can be used to make durable baskets that design to be even survived repeated exposure to high impact processes.
Solutions from ECarbonsteel
When it comes to providing stainless steel solutions, ECarbonsteel specializes in providing different grades of stainless steel.