From towering skyscrapers to the tiniest mechanical parts, steel is the backbone of almost every modern industry. But not all steel is the same. The material composition of steel and its properties can vary widely, depending on the type of steel and its intended use. Understanding the different kinds of steel and how they’re classified helps industries select the right material for the job—be it for construction, manufacturing, or specialized engineering.
In this guide, we’ll break down the steel varieties that dominate the industry. We’ll explore the steel material grades, their properties, and where they fit best in real-world applications. So whether you're a professional looking to understand steel grades or just curious about what makes one metal type different from another, we’ve got you covered.
The Four Main Types of Steel and Their Applications
Steel is generally classified into four main categories: carbon steel, alloy steel, stainless steel, and tool steel. Each steel category has unique properties based on the composition of steel and its intended use.
Stainless Steel
Known for its corrosion resistance, stainless steel is commonly used in kitchenware, medical devices, and architectural structures. The addition of chromium (at least 10.5%) prevents rust and gives stainless steel its shiny appearance.
There are four main grades of stainless steel:
Austenitic Stainless Steel
Highly resistant to corrosion and non-magnetic, austenitic stainless steels are known for their excellent formability and weldability. They are commonly used in food processing equipment, chemical containers, and medical tools because of their hygienic properties and durability in harsh environments.
Ferritic Stainless Steel
Magnetic and less corrosion-resistant than austenitic types, ferritic stainless steels lend good resistance to stress corrosion and cracking. This steel variety is often used in automotive applications, industrial equipment, and home appliances where moderate corrosion resistance and high thermal conductivity are required.
Martensitic Stainless Steel
Known for their strength, hardness, and moderate corrosion resistance, martensitic stainless steels are ideal for applications that require sharp edges or wear resistance. They are commonly found in cutlery, surgical instruments, and industrial tools, where both durability and precision are essential.
Duplex Stainless Steel
A combination of austenitic and ferritic structures, duplex stainless steels provide high strength and excellent resistance to rust, especially in chloride-rich environments. They are widely used in marine applications, chemical processing, and oil and gas industries where both mechanical performance and corrosion resistance are critical.
Carbon Steel
Amongst all kinds of steel, carbon steel is the most commonly used. It’s known for its strength and versatility which make it ideal for construction, pipelines, and automotive parts. The carbon steel composition includes iron and a higher percentage of carbon compared to other steel material types. This makes it harder but less ductile.
Carbon steel grades are classified based on carbon content:
Low Carbon Steel (Mild steel)
Easy to shape, weld, and machine, low-carbon steel is one of the most widely used types of steel material. With a carbon content of less than 0.3%, this steel type offers excellent ductility and malleability. It's the right fit for applications where flexibility is important. Commonly found in construction beams, pipelines, MS wires, and structural frameworks, it is also popular for manufacturing automobile body panels and household appliances. These steels are referred to as grades of mild steel or mild carbon steel grades.
Medium Carbon Steel
Containing between 0.3% and 0.6% carbon, medium-carbon steel strikes a balance between strength and ductility. It provides greater hardness and resistance to wear compared to mild steel grades, while still maintaining some flexibility for forming and machining. This steel variety is commonly used in the production of automotive components like axles, gears, and crankshafts, as well as machinery parts and railway tracks. Medium-carbon steel is often heat-treated to improve its mechanical properties for more demanding applications.
High Carbon Steel
With a carbon content ranging from 0.6% to 1.5%, high-carbon steel is known for its extreme hardness and strength. This type of steel material is meant for applications that require sharp edges or high wear resistance, such as cutting tools, blades, springs, and high-strength wires. However, the increased hardness comes at the cost of reduced ductility so high-carbon steel is more brittle and difficult to weld or form.
Alloy Steel
Alloy steel contains other elements like chromium, nickel, or manganese in addition to carbon. These elements deliver specific properties, such as corrosion resistance or tensile strength which general MS products like MS hot rolled bars often lack. The unique alloy steel composition makes it ideal for aerospace, machinery, and heavy equipment.
The alloy steel category includes:
Low-alloy Steel
Low-alloy steel contains small amounts of alloying elements like chromium, nickel, or molybdenum, which improve its strength and corrosion resistance compared to carbon steel grades. It is commonly used in pipelines, ships, and pressure vessels where both durability and toughness are required. This steel variety is also favoured in structural applications for its ability to perform under stress.
High-alloy Steel
With a higher concentration of alloying elements, high-alloy steel offers exceptional performance in extreme environments. It’s often used in power plants, chemical processing equipment, and other specialized industries where heat, corrosion, and pressure resistance are critical. This type of steel material is known for its superior strength and longevity in demanding applications.
Tool Steel
Tool steel is designed for high durability and hardness. It’s typically used to make cutting tools, molds, and dies that can withstand high temperatures and pressure. The composition of steel in this category includes elements like tungsten, molybdenum, and vanadium, which improve wear resistance and toughness.
Common types of tool steel include:
D series
Known for its high wear resistance and excellent hardness, the D series tool steel is ideal for cutting dies, punches, and shear blades. This steel type's high carbon and chromium content provides superior durability in applications where tools must withstand constant friction and impact.
O series
The O series is oil-hardened tool steel. It delivers good dimensional stability and toughness. It’s commonly used for general-purpose tools like knives, chisels, and gauges, where precision and moderate wear resistance are required. Its ease of machining and hardening makes it a versatile steel variety for many industries.
M series
The M series represents high-speed tool steels designed for cutting tools like drills, end mills, and saw blades. These steels maintain their hardness even at high temperatures, which makes them perfect for high-speed machining and heavy-duty industrial applications. Their superior performance and heat resistance set them apart from other types of steel grades.
Hot-Rolled Steel vs. Cold-Rolled Steel
Steel types are often also classified by production and finishing methods. The two commonly used finishing methods for steel are hot rolling and cold rolling.
Feature | Hot-Rolled Steel | Cold-Rolled Steel |
Production Process | Rolled at high temperatures (above 1700°F) | Rolled at room temperature after initial hot rolling |
Surface Finish | Rough, scaled surface | Smooth, polished finish |
Dimensional Accuracy | Less precise, may have slight variations | High precision with tighter tolerances |
Strength | More malleable, less tensile strength | Higher strength and hardness due to strain hardening |
Applications | Construction beams, railroad tracks, heavy equipment | Automotive parts, appliances, furniture, precision components |
Cost | More cost-effective due to simpler processing | Typically more expensive due to additional processing steps |
Appearance | Dull, with possible surface imperfections | Clean, smooth, and visually appealing |
Formability | Easier to work with for larger structures and shapes | Better for smaller, intricate, or detailed parts |
Common Steel Grades and Standards
The steel industry relies on standardized grading systems to ensure consistency across products. Steel grades reflect the chemical composition, mechanical properties, and manufacturing processes of the steel. Here’s how to decode these systems:
EN Steel Grades
The EN (European Norm) system classifies steels based on chemical composition and mechanical properties. For instance, EN10025 is used for structural steel, while EN1A and EN3B cover mild steel grades. These EN material grades ascertain consistency in steel production across Europe.
ASTM and AISI Grades
The ASTM system classifies steel based on its intended application, while AISI focuses on material composition of steel. For example, ASTM A36 is a common carbon steel grade for structural use, while AISI 304 is a popular stainless steel grade known for its corrosion resistance. Both systems are widely recognized and make sure that steel meets rigorous industry standards.
SAE Grading System
The SAE system uses a four-digit numbering method to describe types of steel grades. The first two digits indicate the steel category, and the last two refer to the carbon content. For example, SAE 1045 is a medium-carbon steel used in machinery and automotive applications for a balance of strength and toughness.
UNS (Unified Numbering System)
Developed in the United States, the UNS (Unified Numbering System) is an internationally recognized system that classifies metal types, including steel, based on the chemical composition of steel and mechanical properties. Each steel grade is assigned a unique alphanumeric code that begins with a letter indicating the metal type, followed by five numbers. For example, UNS S41000 corresponds to 410 stainless steel, while UNS G10450 represents a medium-carbon steel equivalent to AISI 1045.
Which Steel Grade is Best for Your Project?
Choosing the right steel depends on factors like strength, corrosion resistance, and cost. Here’s how to decide based on your needs:
For Construction: Use low-carbon steel like ASTM A36 or EN10025 in forms like MS bright bars. These grades of mild steel grant excellent weldability and affordability.
For Automotive and Machinery: Medium-carbon steel like SAE 1045 or EN8 provides a good balance of strength and ductility.
For Tools and Cutting Applications: Opt for high-carbon steels or tool steels like D2 and M2 which are known for their hardness and wear resistance.
For Corrosive Environments: Stainless steel grades like SS 304 or SS 316 are ideal for their rust resistance and durability.
For Specialized Engineering Projects: Alloy steels with added elements like chromium and molybdenum deliver better performance in extreme conditions.
How to Select the Right Type of Steel for Your Project?
Selecting the right type of steel material for your project isn’t just about strength or appearance—it’s about matching the steel properties to the job at hand. Here’s how to navigate the selection process based on key factors:
Consider the Environment
If your project involves exposure to moisture, chemicals, or extreme temperatures, corrosion resistance is critical. In such cases, stainless steel grades like AISI 304 or 316 are ideal. They contain chromium, which forms a protective layer to prevent rust and degradation. These SS grades are commonly used in kitchens, medical equipment, and marine applications.
For environments where corrosion isn’t a concern, carbon steel grades might be more cost-effective. For example, ASTM A36 is perfect for structural applications where strength is more important than corrosion resistance.
Factor in Strength and Durability
Different projects demand varying levels of strength and flexibility. If you need high tensile strength and wear resistance, alloy steel or tool steel is the way to go. SAE 4140, for instance, is a steel variety known for its toughness and fatigue resistance. It's especially great for machinery and automotive parts.
For general construction or fabrication, mild steel grades like EN 1A or EN 3B are widely used due to their ease of welding and forming. These grades of mild steel are cost-effective and versatile for a range of applications.
Think About Fabrication Needs
If your project involves a lot of cutting, shaping, or welding, you’ll want a steel that’s easy to work with. Mild carbon steel grades are perfect for this because they have low carbon content, which makes them ductile and easy to manipulate. On the other hand, high-carbon steel is harder and more brittle so it's challenging to work with but perfect for cutting tools and blades.
When precision is key, such as in the production of tools or dies, tool steel like the D-series or M-series delivers the hardness and wear resistance needed for demanding applications.
Budget and Availability
While it’s tempting to choose the highest-performing steel type, budget constraints often play a crucial role. Mild steel grades are generally more affordable than stainless steel grades or alloy steels. However, long-term costs should also be considered. For instance, using carbon steel in a corrosive environment might save money upfront, but maintenance and replacement costs will add up over time.
Additionally, local availability can influence your decision. Certain EN steel grades or ASTM standard grades might be more readily available in specific regions. This availability will affect both cost and lead times.
Final Thoughts
Choosing the right type of steel comes down to balancing performance, cost, and environmental factors. Doesn't matter if you’re dealing with carbon steel grades for structural work, mild steel grades for fabrication, or stainless steel grades for corrosion resistance, understanding the widely available steel classification chart and types of steel grades makes sure that you get the best material for the job.
At Fortran Steel, we provide a wide variety of products from renowned steel materials to meet your project’s unique requirements. Our expertise in steel material types and deep knowledge of industry standards—from EN steel grades to ASTM classifications—guarantees you get the right steel product, every time.
Have questions about which steel grade fits your project? Contact us today and let our skilled team help you find the perfect solution for all your steel needs.
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