304 stainless steel and 316 stainless steel are both widely used steels in the manufacturing industry.
In this guide, we will explore the characteristics, composition and applications of 304 stainless steel and 316 stainless steel.
More importantly, we will also explore how to choose between these two materials under different needs.
Keep reading:
Table of Contents
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Introduction
304 Stainless Steel
304 stainless steel, also called A2 stainless steel (ISO 3506 standard), is a extensively used austenitic stainless steel containing 18%-20% chromium and 8%-10.5% nickel. It is popular for its balanced corrosion resistance and formability. It has good corrosion resistance, heat resistance, low-temperature strength and mechanical properties; good hot workability such as stamping, bending, etc., without heat treatment hardening phenomenon (use temperature -196 ℃ ~ 800 ℃).304 stainless steel is suitable for food processing, storage and transportation, with good workability and weldability.
316 Stainless Steel
316 stainless steel, also known as A4 stainless steel (ISO 3506 standard), contains an additional 2-3% molybdenum, providing improved corrosion resistance, especially in chloride-containing environments.316 stainless steel is often referred to as a marine grade stainless steel due to its enhanced resistance to corrosion by chloride, and its superior qualities make it ideal for a range of demanding applications.
Chemical composition
316 stainless steel typically has slightly higher strength and hardness than 304 stainless steel due to its higher nickel and molybdenum content. This makes 316 more suitable for high loading and high temperature environments.
304 Stainless Steel
| C | Si | Mn | Ni | P | S | Cr | N |
| max 0.07 | max 1 | max 2 | 8 – 10.5 | max 0.045 | max 0.15 | 17.5 – 19.5 | max 0.11 |
316 Stainless Steel
| C | Si | Mn | Ni | P | S | Cr | Mo | Cu |
| max 0.08 | max 0.65 | 1 – 2.5 | 11 – 14 | max 0.03 | max 0.03 | 18 -20 | 2 – 3 | max 0.75 |
304 vs 316 Stainless Steel Comparison
316 stainless steel is better than 304 stainless steel in corrosion resistance, strength and hardness due to the presence of molybdenum, but the cost is also relatively high. 316 has a PREN (pitting corrosion equivalent) value of 24.2 compared to 304’s 19.0, reflecting 316’s advantage in pitting corrosion resistance .
Application Scenarios of 304 and 316
304 Stainless Steel is used in general corrosion resistant environments, such as housewares, building decoration, food processing equipment.
316 stainless steel is commonly used in highly corrosive environments such as the marine, chemical and paper industries, as well as applications requiring high resistance to chloride corrosion.
304 vs 316 Stainless Steel: Which Should l Use?
These are some key factors that should be considered when choosing between 304 and 316 stainless steel.
Corrosion Resistance: 316 stainless steel has greater corrosion resistance than 304 stainless steel due to the presence of molybdenum, especially in chloride-containing environments such as seawater and the chemical processing industry. If the application environment is exposed to high concentrations of salt or corrosive agents, 316 is a more suitable choice.
Strength and hardness: 316 stainless steel usually has higher strength and hardness than 304 stainless steel, which makes it more eligible for high loading and high temperature environments.
Machinability: 304 stainless steel is more easier to cold processing and weld, and the 316 steel stainless is more difficult to shape because of the higher alloy content.
Production cost: The cost of 316 stainless steel is usually higher than that of 304 stainless steel, which is mainly because of the higher nickel and molybdenum content in its alloy composition.
Application Scenario: 304 stainless steel is suitable for general corrosion-resistant environments, such as housewares, architectural decoration, food processing equipment and so on. While 316 stainless steel is commonly used in highly aggressive industrial or ocean atmospheres, as well as applications that require high resistance to chloride corrosion .
Heat Resistance: Although the two steel both have good heat resistance, in the in continuous using, 316 stainless steel should be avoided in the range of 800-1575 degrees, while 304 stainless steel retains its toughness at high temperatures.
Weldability: 304 stainless steel has good weldability and can be welded using all standard welding methods. 316 stainless steel also has good weldability but may need a higher degree of skill when welding.
Mouldability: While 304 stainless steel is easier to shape, 316 stainless steel is relatively difficult to machine and requires higher cutting forces and cutting speeds.
Price Factor: 304 stainless steel is more economical due to its lower cost. 316 stainless steel is relatively more expensive due to its excellent corrosion resistance and high strength, among other things.
According to the application requirements, cost budget and expected performance, the most eligible type of stainless steel can be selected. When budget is limited or corrosion resistance is not required, 304 may be an appropriate choice. And in applications requiring higher corrosion resistance and strength, 316 may be a better choice.
Conclusion
Although 304 and 316 stainless steels are similar in many properties, they have very differences in chemical composition, corrosion resistance, cost and application scenarios. Users should choose the most appropriate steel grade based on their needs and budget.
FAQ
Which is more corrosion resistant: 304 vs 316 stainless steel?
316 stainless steel is more corrosion resistant than 304 because 316 stainless steel has molybdenum added to it, making it more suitable for harsh environments such as coastal or industrial areas.
Which is more cost effective: 304 vs 316 stainless steel?
304 stainless steel is generally more cost effective than 316 because it is cheaper while still providing good corrosion resistance.
Can 304 vs 316 stainless steel be used in food processing equipment?
Both 304 and 316 stainless steel can be used in food processing equipment, but if it is in an environment with corrosive elements, 316 stainless steel is more suitable.
Are 304 vs 316 stainless steel magnetic?
Both 304 and 316 stainless steel are generally non-magnetic in the annealed state. However, when cold worked, 304 can become slightly magnetic, while 316 is non-magnetic.