The Difference Between 304 and 316 Stainless Steel

What is 316 Stainless Steel?

316 stainless steel is a grade of austenitic stainless steel like 304 but with the addition of molybdenum, which significantly increases its corrosion resistance, especially to chlorides and other industrial solvents. Adding molybdenum is crucial as it enhances corrosion resistance, particularly against chlorides and other industrial solvents. It makes 316 stainless steel suitable for applications in harsh chemical environments or marine conditions where higher chloride concentrations can cause pitting and corrosion in less resistant alloys.

The typical composition of 316 stainless steel includes approximately:

• 16% to 18% chromium
• 10% to 14% nickel
• 2% to 3% molybdenum
• Smaller amounts of manganese, silicon, and carbon

There are several variants of 316 stainless steel, including 316L, which has a lower carbon content to improve weldability and decrease the risk of corrosion after welding. Another variant is 316Ti, which includes titanium for stabilization against chromium carbide formation.

316 stainless steel is often considered one of the most suitable choices when selecting an austenitic stainless steel for marine applications. Other common applications of 316 stainless steel include:

• Chemical processing and storage equipment
• Refinery equipment
• Medical devices
• Marine environments, especially those with chlorides present

316 Stainless Steel Grade Guide Video

Learn more about 316 Stainless Steel meaning with our Grade Guide video blog:

What are the Differences Between 304 Stainless Steel and 316 Stainless Steel?

While 304 stainless steel and 316 stainless steel are both common austenitic grades with excellent properties, they have several key differences that affect their applications and performance:

Chemical Composition

The most significant difference between 304 grade stainless steel and 316 stainless steel is in their chemical composition. 304 stainless steel contains approximately 18% chromium and 8% nickel, with no significant molybdenum content. In contrast, 316 stainless steel contains approximately 16-18% chromium, 10-14% nickel, and 2-3% molybdenum. The addition of molybdenum in 316 stainless steel is the primary differentiating factor, providing enhanced corrosion resistance, particularly against chlorides and other industrial chemicals.

Corrosion Resistance

While both grades offer good corrosion resistance, there are notable differences. 304 stainless steel provides excellent resistance to most oxidizing acids and general corrosive environments. However, it may be susceptible to pitting and crevice corrosion in environments with high chloride content. 316 stainless steel offers superior resistance to chlorides, saltwater environments, and industrial chemicals. The added molybdenum in 316 stainless steel improves resistance to pitting corrosion and makes it more suitable for marine applications.

Cost

304 stainless steel is generally less expensive and more widely available, making it the economical choice for many applications. 316 stainless steel is typically 20-30% more expensive than type 304 stainless steel due to the addition of molybdenum and higher nickel content.

Applications

304 stainless steel is commonly used in kitchen equipment, food processing, general-purpose equipment, interior architectural applications, and environments without significant chloride exposure. 316 stainless steel is preferred for marine environments, chemical processing equipment, pharmaceutical equipment, surgical instruments, boat fittings, and exterior applications in coastal areas where ss grade 304 might experience premature corrosion.

Temperature Performance

There are subtle differences in how these grades perform at different temperatures. 304 stainless steel maintains good mechanical properties at both elevated and sub-zero temperatures. 316 stainless steel offers slightly better strength at elevated temperatures and maintains excellent toughness at sub-zero temperatures.

Which Should You Use: Grade 304 or Grade 316?

Here are some situations where 304 stainless steel may be the better choice:

• The application requires excellent formability. The higher molybdenum content in Grade 316 stainless steel can have adverse effects on formability.
• The application has cost concerns. Grade 304 stainless steel is typically more affordable than Grade 316 stainless steel.

Here are some situations where 316 stainless steel may be the better choice:

• The environment includes a high amount of corrosive elements
• The material will be placed underwater or be exposed to water consistently
• In applications where greater strength and hardness are required

For most general applications where moderate corrosion resistance is needed, 304 grade stainless steel offers an excellent balance of performance and value that’s difficult to surpass.