In almost any project, this question is being raised over and over again by someone: do we need to use stainless steel or will regular steel do the job and save us some money? The question may seem primitive, and truth be said, it should be so, but the answer to this question rarely comes up in ordinary conversations, due to such details as how much moisture would be present, whether the part will come into contact with food or chemical agents, or what amount of money you are ready to plug in now to preserve yourself from hassle and maintenance in future. From the engineering point of view, stainless steel and carbon steel are basically nothing but iron and carbon that construct these materials. However, they differ in only one component – chromium, which is responsible for making the difference.
If you have come to the conclusion that stainless steel is a good material choice, check our Stainless Steel Pipe Grades Charts explaining 304, 304L, 316 and 316L types.
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What Is Carbon Steel?
Carbon steel is a combination of iron and carbon that has no substantial chromium or other corrosion-resistant components mixed up. Carbon steel is normally divided into three types based on its carbon contents: low-carbon steel, which has up to 0.3% of carbon and has remarkable ductility and weldability and is mainly used to make pipes and construction structures; medium carbon steel, which has 0.3-0.6% of carbon and enables finding balance between hardness and ductility, is used in the production of auto parts and devices; and high carbon steel, which has more than 0.6% of carbon and is very strong and hard but quite brittle and is used in the creation of cutting tools and springs. The most popular grades of carbon steel used in the production of pipes include A36 structural steel and A106 or A53 carbon steel pipes.
What Is Stainless Steel?
Stainless steel is regarded as an iron alloy that contains carbon and which contains at least 10.5% chromium. Chromium in stainless steel acts with the oxygen in the air and creates a breathable, transparent oxide film that protects stainless steel from corrosion. Even if this film is damaged, it will heal by recreating itself, provided that both oxygen and chromium are available. There are feature categories of stainless steel: austenitic (for example, 304 and 316), ferritic, martensitic, and duplex. You can refer to our Stainless Steel Pipe Grades Charts for information on various grades of austenitic steel and our Duplex Stainless Steel guide for applications which require specific knowledge about high strength and corrosion resistance in duplex steel.
Carbon Steel vs Stainless Steel: The Full Comparison Chart
The table below compares both material families directly, using representative grades on each side, A36 for carbon steel and 304 or 316 for stainless steel.
| Property | Carbon Steel | Stainless Steel |
| Composition | Iron and carbon, up to about 2.1% carbon, no significant chromium | Iron, carbon and a minimum of 10.5% chromium, often with nickel and molybdenum |
| Corrosion Resistance | Low. Rusts without a coating, galvanising or paint | High. A passive chromium oxide layer resists rust and heals itself if scratched |
| Typical Tensile Strength | 400 to 550 MPa (for example, A36) | 485 to 620 MPa for 304 and 316, up to 795 MPa for duplex grades |
| Hardness | Moderate, increasing with carbon content | Moderate for austenitic grades, generally tougher and more ductile |
| Weldability | Generally excellent for low carbon grades, few special precautions | Good, but heat input must be controlled to avoid sensitisation, especially in heavier sections |
| Magnetic Properties | Yes, magnetic | Austenitic grades such as 304 and 316 are not magnetic. Ferritic, martensitic and duplex grades are magnetic |
| Relative Cost | Lower, used as the base reference | Higher, typically two to four times carbon steel due to chromium and nickel content |
| Typical Applications | Structural steel, general piping, automotive parts, construction | Food and pharmaceutical equipment, chemical processing, marine equipment, medical devices, architecture |
Mechanical Properties: Which Is Actually Stronger?
| Property | Carbon Steel | Stainless Steel |
| Typical tensile strength | ~400–550 MPa for A36 | ~485–620 MPa for common 304/316 grades |
| Typical yield strength | ~250 MPa for A36 | ~170–215 MPa for common 304/316 grades |
| Strength comparison | Good strength at relatively low cost | Similar or moderately higher tensile strength, depending on grade |
| Grade dependence | Strength varies by carbon steel grade | Strength varies significantly by stainless grade |
| Key consideration | Often selected for structural strength and cost efficiency | Combines adequate strength with corrosion resistance |
Key point: Neither material is universally stronger. The specific grade, product form and condition determine the actual mechanical properties.
Corrosion Resistance: Why Stainless Steel Does Not Rust
| Factor | Carbon Steel | Stainless Steel |
| Corrosion resistance | Low without protection | Generally high |
| Chromium content | Typically below stainless steel levels | Minimum 10.5% chromium |
| Rust formation | Forms iron oxide when exposed to moisture and oxygen | Forms a protective chromium oxide passive film |
| External protection | Often requires paint, galvanising or coatings | Usually does not require protective coating for general corrosion resistance |
| Scratch or surface damage | Exposed steel can begin corroding | Passive film can reform when oxygen is available |
| Wet or corrosive environments | Requires suitable protection and maintenance | Often better suited, depending on grade and environment |
Key point: Stainless steel's chromium content provides inherent corrosion resistance, while carbon steel generally requires additional protection in corrosive environments.
Cost Comparison: Why Stainless Steel Costs More
| Cost Factor | Carbon Steel | Stainless Steel |
| Initial material cost | Generally lower | Generally higher |
| Alloying elements | Primarily iron and carbon | Contains chromium and may contain nickel, molybdenum and other elements |
| Corrosion protection | May require coating or galvanising | Usually provides inherent corrosion resistance |
| Maintenance | Can require recoating or corrosion maintenance | Often lower in suitable corrosive applications |
| Service life | Depends heavily on corrosion protection | Can provide longer service in corrosive environments |
| Life-cycle cost | Lower upfront cost but maintenance can increase total cost | Higher upfront cost but potentially lower maintenance costs |
Key point: Carbon steel generally has the lower purchase price, while stainless steel can offer lower maintenance and better long-term performance where corrosion is a concern.
Applications
Carbon Steel
- Structural steel: Used for buildings, bridges and general structural frameworks.
- General piping: Suitable for water, gas and industrial piping where severe corrosion is not a concern.
- Automotive components: Used for components requiring good strength and cost efficiency.
- Construction: Commonly selected for general construction and fabrication.
- Cost-sensitive applications: Preferred where high strength and low material cost are priorities and protective coatings can be maintained.
Stainless Steel
- Food and pharmaceutical equipment: Suitable where hygiene and corrosion resistance are essential.
- Chemical processing: Used for equipment exposed to corrosive chemicals and process fluids.
- Marine and offshore equipment: Suitable for prolonged exposure to moisture and chloride environments.
- Medical devices: Used where corrosion resistance and cleanliness are required.
- Architectural applications: Selected for its corrosion resistance, durability and appearance.
Which Should You Choose? A Simple Decision Framework
- Will the part be exposed to moisture, chemicals or chlorides for extended periods? If yes, lean toward stainless steel.
- Is hygiene or food contact a requirement, such as in food processing or pharmaceutical equipment? Choose stainless steel.
- Is upfront budget the primary constraint and the environment is dry or coatings are acceptable? Carbon steel is usually the better fit.
- Is raw strength per unit cost more important than corrosion resistance, such as in structural framing? Carbon steel generally wins on cost efficiency.
- Will access for maintenance or coating renewal be difficult or expensive once installed? That favours stainless steel despite the higher upfront cost.
Standards Referenced
- ASTM A36 covers structural carbon steel plate and shapes.
- ASTM A106 and ASTM A53 cover carbon steel pipe for high temperature and general service.
- ASTM A312 covers seamless and welded austenitic stainless steel pipe.
Frequently Asked Questions
It depends on the specific grades compared. Standard 304 or 316 stainless has a modest tensile strength advantage over standard carbon steel such as A36. Duplex stainless grades are significantly stronger than both, close to twice the yield strength of standard austenitic stainless or carbon steel.
Stainless steel contains chromium and often nickel, both of which are significantly more expensive raw materials than the iron and carbon used in carbon steel, and stainless steel also requires more controlled melting and finishing.
Yes, but it requires a compatible filler metal, usually a stainless filler with higher chromium and nickel content, and careful control of heat input, since the two materials have different thermal expansion rates and welding characteristics.
Yes. Carbon steel has no chromium to form a protective oxide layer, so it rusts readily when exposed to moisture and oxygen unless coated. Stainless steel resists rust because of its self-healing chromium oxide film.
Stainless steel generally performs better outdoors without maintenance, since it resists rust on its own. Carbon steel can also be used outdoors if properly coated, galvanised or painted and that coating is maintained over time.
Carbon steel is magnetic. Stainless steel varies by family. Austenitic grades such as 304 and 316 are generally not magnetic, while ferritic, martensitic and duplex stainless grades are magnetic.
Why Source From Metinox Overseas
Metinox Overseas supplies ASTM and ASME certified stainless steel and carbon steel pipes with over 45 years of experience, ISO 9001 certified processes and Mill Test Certificates for every order. We serve international markets across the petrochemical, oil and gas, power generation and heavy engineering industries.
Related Guides
Stainless Steel Pipe Grades Chart: 304, 304L, 316, 316L, 321 and 347 Compared
Stainless Steel Pipe Weight Chart: Weight Per Meter by Size and Schedule
Duplex Stainless Steel Grades: 2205, 2507 and Their Applications
