Table of content
Introduction
When choosing a pipe, the material of the pipe is very important. It is crucial to understand the difference between 303 and 304 stainless steel. Both are commonly used stainless steels, but they are slightly different. Specific requirements such as machinability, corrosion resistance, weldability, and cost can be considered when purchasing.Comparing 303 and 304 Stainless Steel.
Differences in chemical composition
The difference in the chemical composition of 303 and 304 stainless steel has significant differences in its performance and application fields.
The following is the chemical composition table of 303 and 304 stainless steel.
303 chemical composition
|
Grade |
C |
Mn |
Si |
P |
S |
Cr |
Mo |
Ni |
Se |
|
|
303 |
min. max. |
– 0.15 |
– 2.00 |
– 1.00 |
– 0.20 |
0.15 – |
17.0 19.0 |
– |
8.0 10.0 |
– |
|
303Se |
min. max. |
– 0.15 |
– 2.00 |
– 1.00 |
– 0.20 |
0.06 – |
17.0 19.0 |
– |
8.0 10.0 |
0.15 min |
304 chemical composition
|
|
304 |
304L |
304H |
|
C |
0.0 – 0.07 |
0.0 – 0.03 |
0.04 – 0.08 |
|
Mn |
0.0 – 2.0 |
0.0 – 2.00 |
0.0 – 2.0 |
|
Si |
0.0 – 1.00 |
0.0 – 1.00 |
0.0 – 1.0 |
|
P |
0.0 – 0.05 |
0.0 – 0.05 |
0.0 – 0.04 |
|
S |
0.0 – 0.03 |
0.0 – 0.02 |
0.0 – 0.02 |
|
Cr |
17.50 – 19.50 |
17.50 – 19.50 |
17.00 – 19.00 |
|
Ni |
8.00 – 10.50 |
8.00 – 10.50 |
8.00 – 11.00 |
|
Fe |
Balance |
Balance |
Balance |
|
N |
0.0-0.11 |
0.0-0.11 |
0.0 – 0.10 |
Machinability: 303 vs 304
The sulfur (S) in the chemical composition of 303 stainless steel can improve its machinability.
The sulfur (S) content in the chemical composition of 304 stainless steel is lower than that of 303, making its machinability slightly lower.
Corrosion resistance: 303 vs 304
The corrosion resistance of 303 and 304 stainless steels differs due to their chemical composition. Both contain similar amounts of chromium and nickel, which contribute to their corrosion resistance.
303 stainless steel has a lower corrosion resistance than 304 stainless steel due to the addition of sulfur. Grade 303 is more susceptible to corrosion when exposed to chlorides or sulfur compounds. Therefore, it is not suitable for use in marine or other similar environments, as these environments can cause rapid pitting.
304 stainless steel has a lower amount of added sulfur and has a higher corrosion resistance than 303 stainless steel. Grade 304 has excellent corrosion resistance in all environments. It can be used in food processing, chemical pipelines and marine environments.
Strength and durability: 303 vs 304
The strength and durability of 303 and 304 stainless steels are primarily based on mechanical properties.
Mechanical properties of 303 grade stainless steel
|
Grade |
303 |
|
Tensile Strength (MPa) |
620 MPa |
|
Proof Stress (MPa) |
240 MPa |
|
Elongation A50 mm |
35Min% |
Mechanical properties of 304 grade stainless steel
|
Grade |
304 |
304L |
|
Tensile Strength (MPa) |
540 – 750 |
520 – 700 |
|
Proof Stress (MPa) |
230 Min |
220 Min |
|
Elongation A50 mm |
45 Min % |
45 Min % |
Cost considerations: 303 vs 304
The costs of 303 and 304 mainly include the following aspects.
Material cost: 303 has a higher sulfur content, so the cost is higher than 304.
Additive cost: The mechanical properties of 303 are slightly higher than 304, so the processing performance and cost are also higher.
Manufacturing cost: 304 has excellent weldability and there is no risk of thermal cracking. Because the welding cost is lower.
Maintenance cost: 304 has stronger corrosion resistance than 303, and the cost of 303 is higher under the same environment.
But in addition to considering the cost, the specific use is more important to consider the project needs.
Choosing Between 303 and 304 Stainless Steel for Plumbing Projects
Factors to consider when selecting stainless steel grade
Corrosion resistance requirements
First of all, we should consider the corrosion resistance requirements of the project construction environment. For example, in marine environments, chemical transportation and high temperature environments with high corrosion resistance, we should choose 304 stainless steel with high corrosion resistance.
Machining and fabrication needs
Consider whether the material needs a lot of processing. If it does, 303 has sulfur added and has higher mechanical properties, and its machinability is excellent. However, if there is a complex welding process, 304 has simpler operation requirements.
Cost and availability
In terms of cost, different cost considerations are also introduced above. Relatively speaking, the cost of 303 is higher than that of 304.
Recommendations for specific plumbing applications.
In highly corrosive marine and chemical environments, 304 is considered as a material, and 303 is more suitable for some bolts, nuts and electrical switch components.
Conclusion
The main differences between 303 and 304 stainless steel include: chemical composition, mechanical properties, corrosion resistance, cost and application. If you need to know more, please contact us.
Frequently Asked Questions
1.What is 303 Stainless Steel?
303 stainless steel is a type of austenitic stainless steel. It has a high sulfur content and high machinability. It is often used in production where a large number of automatic screw machine processing are required.
2.What is 304 Stainless Steel?
304 stainless steel is also a kind of austenitic stainless steel. It is widely used because of its excellent corrosion resistance in various environments.
3.How do I identify 303 and 304 stainless steel?
The appearance of 303 and 304 is not much different, only the chemical composition is different. Therefore, the best way to distinguish the two materials is to use chemical analysis and mechanical property testing.
4.Can 303 and 304 stainless steel be used interchangeably?
In environments with low corrosion resistance, the two materials can be used interchangeably.
5.Which grade is more cost-effective?
The two materials have different cost performances in different usage environments. However, in low-corrosive environments, 303 stainless steel has a relatively higher cost performance.
