What is the difference between 304 and 316? These are the two most common types of stainless steel, and with so many grades available, making the right choice is key. Understanding the nuances between them is essential, and reliable and professional stainless steel tube manufacturers and suppliers will help you make an informed choice. We focus on their applications in stainless steel pipe and fittings. Before reading this article, please understand what is 304 steel and what is 316 steel.
What's The Difference Between 304 And 316? The Core Distinction!
304 and 316 are both austenitic stainless steels with good corrosion resistance. The main difference is in their chemical composition: 316 contains molybdenum, while 304 contains no molybdenum. Molybdenum significantly enhances corrosion resistance. The effect of molybdenum is particularly noticeable in environments rich in chlorides. This makes 316 a premium choice.
Key Differences: 304 and 316 Explained
316 contains 2-3 per cent molybdenum, while 304 contains no molybdenum. This element is the main difference and significantly improves corrosion resistance.
304 is very resistant to general atmospheric corrosion. 316 has greater corrosion resistance, resisting pitting and crevice corrosion. Excellent in chlorinated environments such as seawater.
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304 is generally more economical and offers excellent value for general purpose applications. 316 has a higher material cost, and the increased performance of 316 in critical applications justifies the investment.
Both grades have good performance at elevated temperatures. 316 has better creep strength due to the presence of molybdenum and maintains higher integrity at elevated temperatures.
Both 304 and 316 are easy to weld. For heavily welded sections, it is best to use low carbon materials (304L, 316L) to prevent sensitisation.
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Chemical Composition: 304 vs. 316
| Element | 304 Stainless Steel | 316 Stainless Steel |
|---|---|---|
| Cr | 17.5-19.5 | 16.0-18.0 |
| Ni | 8.0-10.5 | 10.0-14.0 |
| Mo | None | 2.0-3.0 |
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Mechanical Properties: 304 vs. 316
| Element | 304 Stainless Steel | 316 Stainless Steel |
|---|---|---|
| Tensile Strength | ≥515MPa(75ksi) | ≥515MPa(75ksi) |
| Yield Strength (0.2% Offset) | ≥205MPa(30ksi) | ≥205MPa(30ksi) |
| Elongation | ≥40 | ≥40 |
| Hardness (HRB) | ≤92 | ≤95 |
| Density | 8.0g/cm³ | 8.0g/cm³ |
| Melting Range | 1400−1450°C | 1370−1400°C |
Typical Applications: 304 vs. 316 Stainless Steel Pipe & Fittings
| Application Type | 304 Stainless Steel | 316 Stainless Steel |
|---|---|---|
| General Service | Water lines, basic food processing | Marine, Chemical Processing, Medical |
| Corrosive Env. | Mild acids, atmospheric exposure | Chlorides, Seawater, Strong Acids |
| High Hygiene | General food, dairy | Pharmaceutical, Surgical, Brewery |
| Structural | Architecture, railings | Offshore, Coastal, Industrial Exhaust |
| Temperature | Moderate to High | Higher temp process lines |
Making the Right Choice for Your Piping Systems
- Choose 304 for general purpose applications, which is cost-effective. It has good corrosion resistance and is ideal for freshwater systems.
- Choose 316 for harsh environments, suitable for marine environments. Can be used in chemical processing, resistant to chlorides and high temperatures.
Sourcing Stainless Steel Pipe and Fittings
- Verify Grades: Always confirm the exact grade and request a Material Test Report (MTR).
- Compliance: Check for compliance with ASTM, ASME, and other relevant standards.
- Supplier reputation: Work with trusted manufacturers. They can provide reliable 304 and 316 products and have certifications(e.g. ISO 9001 and CE-PED).
- Product form: Specify the correct pipe size or fitting type (e.g., seamless, butt-welded fittings).
View Stainless Steel Tube Specification Document
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