Should You Choose 316 or 304 Stainless Steel Pipes?
While stainless steel 316 and 304 share many similarities, each also has distinct characteristics. If you’re looking for information to compare these two types of stainless steel, aiming to better understand their differences as well as the pros and cons of each, continue reading Sơn Hà SSP’s detailed article below!
Overview of 304 Stainless Steel Pipes
304 stainless steel pipes belong to the Austenitic stainless steel class. The primary composition of 304 stainless steel includes 18-20% chromium, 8-11% nickel, 2% manganese, 1% silicon, and the remainder is iron along with trace impurities (<0.1%). This is the most common and well-known stainless steel type in everyday life, widely used in applications that require moderate corrosion resistance, such as household items, kitchen equipment (pots, pans, cutlery), machinery, and building materials in industries (stainless steel pipes, industrial pipe fittings).
Inox 304
One of the major advantages of 304 stainless steel is its ease of fabrication, welding, and forming, making it ideal for the mass production of consumer goods. However, 304 stainless steel has limitations in terms of corrosion resistance when exposed to strong chemicals or seawater, where chloride ions can lead to corrosion.
Alongside 304 stainless steel, 316 stainless steel is also widely used across various industries. So, what are the distinctive features of 316 stainless steel? Let’s explore them below.
Overview of 316 Stainless Steel Pipes
Also part of the Austenitic stainless steel class, 316 stainless steel pipes contain at least 16-18% chromium, at least 11-14% nickel, 2% molybdenum, 2% manganese, 1% silicon, with the remainder being iron and trace impurities (<0.1%). Additionally, 316 stainless steel contains about 2-3% molybdenum, which significantly enhances its corrosion resistance in harsher environments, especially in applications exposed to saltwater or highly corrosive chemicals.
The Role of Molybdenum in Enhancing Corrosion Resistance in 316 Stainless Steel
Thanks to its molybdenum content, 316 stainless steel is highly resistant to corrosion in harsh environments. This type of stainless steel can withstand chloride-containing conditions that 304 stainless steel cannot handle. Due to its resilience against corrosive elements, 316 stainless steel is widely used in marine industries, chemical production, and medical equipment like surgical tools and implants. Additionally, 316 stainless steel’s excellent heat resistance makes it suitable for applications that require sustained strength at high temperatures.
Comparison of 316 and 304 Stainless Steel Pipes
3.1.Composition of 316 vs. 304 Stainless Steel
The key difference in the composition of 304 and 316 stainless steel is the addition of molybdenum (Mo) (2-3%) in 316, which enhances its corrosion resistance in harsh environments. Additionally, the nickel (Ni) content in 316 stainless steel is higher, further improving its rust resistance compared to 304.
Below is a table showing the composition of the two types of stainless steel:
| Composition | Inox 304 (%) | Inox 316 (%) |
| Cr (Chromium) | 18 – 20 | 16 – 18 |
| Ni (Nickel) | 8 – 11 | 11 – 14 |
| Mo (Molybdenum) | 0 | 2 – 3 |
| C (Carbon) | 0.08 | 0.08 |
| Mn (Manganese) | 2 | 2 |
| Si (Silicon) | 1 | 1 |
| P (Phosphorus) | 0.045 | 0.045 |
| S (Sulfur) | 0.03 | 0.03 |
3.2. Physical Properties of 316 and 304 Stainless Steel
Overall, due to only minor differences in their compositions, the crystal structures of 316 and 304 stainless steel are quite similar, leading to minimal variation in their physical properties. However, some differences in their physical characteristics are as follows:
| Physical Properties | Inox 304 | Inox 316 |
| Corrosion Resistance | Good in general environments; susceptible to chloride ion corrosion | Excellent in chloride environments, strong chemicals, and seawater |
| Heat Resistance | Good up to 870°C; reduces in extreme heat | Good up to 925°C, with better durability and oxidation resistance |
| Mechanical Strength | Tensile strength: 505 MPa, Elongation: 40% | Higher mechanical strength in harsh environments compared to 304 |
| Machinability and Weldability | Easy to machine, bend, and weld | Less machinable than 304 |
| Magnetic Properties | Non-magnetic in annealed state, may become magnetic after processing | Non-magnetic in annealed state, less magnetic than 304 after processing |
| Thermal Expansion | Better | Lower |
| Density (g/cm³) | 8 | 8 |
| Oxidation Resistance | Good at high temperatures but less than 316 in humid or chemical environments | Superior in humid and chemical environments |
3.3.Applications of 304 and 316 Stainless Steel
Each type of stainless steel has its own advantages and limitations, making it suitable for different applications. 304 stainless steel is commonly used in household items and general construction due to its lower cost and moderate corrosion resistance. In contrast, 316 stainless steel is known for its superior corrosion resistance in harsh environments. Below is a comparison of the applications for these two types of stainless steel:
| Applications | Inox 304 | Inox 316 |
| Food Industry | Suitable for food and beverage processing due to mild corrosion resistance. Examples: brewing machines, dairy equipment | Used in food applications, especially where salt or strong chemicals are present |
| Medical Equipment | Less commonly used | Widely used in medical equipment production |
| Kitchen Equipment | Commonly used in sinks, pots, and utensils | Less common due to higher cost but used for premium-grade equipment |
| Chemical Industry | Unsuitable for strong chemicals or highly corrosive environments | Ideal for the chemical industry due to superior corrosion resistance. Examples: storage tanks, machinery in chemical facilities |
| Indoor & Outdoor Architecture | Suitable for outdoor structures but less effective in chloride-containing environments | Preferred for outdoor structures, especially in marine or chemical environments |
| Marine Industry | Unsuitable for marine applications or seawater | Ideal for marine applications and coastal structures due to seawater corrosion resistance. Examples: marine fittings like deck cleats, pulleys, bolts, nuts |
3.4. Cost Difference Between 316 and 304 Stainless Steel
In the market, stainless steel 316 generally costs over 30% more than 304. The primary reason for this is the higher nickel content in 316, which is at least 3.00% more than in 304, along with an additional 2.00% of molybdenum.
Should You Choose 316 or 304 Stainless Steel Pipes?
In theory, 316 stainless steel is more durable and reliable than 304. However, the decision between 304 and 316 stainless steel pipes should be based on the environment and technical requirements of the project.
304 stainless steel pipes are a popular choice due to their reasonable price, high durability, and good corrosion resistance in standard conditions, making them suitable for household, construction, and light industrial applications. However, with added molybdenum content, 316 stainless steel offers superior corrosion resistance. Therefore, if your project will be exposed to harsh environments, such as seawater, strong chemicals, or conditions containing salt and chloride ions, 316 stainless steel pipes should be the preferred choice.
Conclusion
Even a slight difference in nickel and molybdenum content leads to significant variations in the physical, chemical properties, and applications of 316 and 304 stainless steels. Understanding and choosing the right type of stainless steel is essential to ensure long-term protection for your project.
Son Ha SSP – Vietnam’s Leading Supplier of 316 and 304 Stainless Steel Pipes
We are committed to delivering:
– High-quality cold-rolled coils with superior durability, strength, and exceptional corrosion resistance.
– A wide range of coil types in various sizes to meet diverse project needs.
– A standardized production process that strictly adheres to international standards.
– Dedicated consultation services, ready to answer your questions and support you throughout your project.
For more information or consultation on Son Ha SSP’s 316 and 304 stainless steel pipes, contact our experts for detailed assistance through:
Hotline: 1800 6566
Website: http://sonhassp.com/
