What are Steel Grades: Systems, Specs & Application Recommendations?

Steel grades are standardized classifications outlining steel’s chemical composition, mechanical properties, and intended applications. This blog covers 4 global core systems (ASTM, AISI/SAE, EN, JIS) and regional ones, plus application-specific grade tips. For buyers, grades eliminate guesswork, ensuring performance reliability, regulatory compliance, and cost efficiency.

Table of Contents

• What Are Steel Grades?
• Why Do Steel Grades Matter For Buyers?
• What Are the Main Types of Steel Grade Systems?
• ASTM International Steel Grade System
• AISI/SAE Steel Grade System
• EN Steel Grade System
• JIS Steel Grade System
• Other Steel Grade Systems
• What Steel Grades Fit Common Applications?
• Conclusion

What Are Steel Grades?

Steel grades are standardized classifications that systematically define a steel’s chemical composition, mechanical properties, and intended industrial applications. They codify parameters like carbon content (ranging from 0.05% in low-carbon steels to over 1.5% in high-carbon alloys, per Wikipedia’s Steel Grades entry), alloying elements (e.g., chromium for corrosion resistance, nickel for toughness), and mechanical thresholds such as tensile strength (measured in MPa or ksi) and yield strength.

Beyond material specs, grades align with global standards—ASTM dominates North America, EN governs Europe, and JIS guides Asian markets—creating a universal benchmark for consistency across manufacturers.

 

As EconSteel’s How to Read Steel Grades emphasizes, this system eliminates ambiguity: a grade designation instantly communicates whether a steel suits structural framing, pressure vessels, or automotive components, bridging technical complexity and practical purchasing decisions. By distilling chemical, mechanical, and regulatory layers into a single identifier, steel grades act as the industry’s shared language, ensuring buyers, engineers, and suppliers speak the same technical dialect.

 

Why Do Steel Grades Matter For Buyers?

Steel grades are critical for buyers because they take the guesswork out of steel selection. They ensure buyers’ purchases align with functional requirements, comply with local regulations, and stay within budget—preventing costly errors or wasted resources. Without clear grades, buyers might select steel that is too weak, fails to meet safety standards, or incurs unnecessary costs, all of which can delay projects or lead to significant issues later.

 

To Secure Reliable Performance

Grades set clear parameters for steel’s functionality. For example, ASTM A36 steel has a tensile strength of 58–80 ksi. 316 stainless steel also offers enhanced corrosion resistance in saltwater due to its molybdenum content, according to Viraj’s analysis. If buyers select the wrong grade—such as using low-yield steel for a crane beam or overlooking chromium content in a chemical plant—they risk structural collapse or accelerated degradation. Grades also indicate steel’s heat tolerance: EN 10216-2 P265GH can withstand temperatures over 500°C for boiler applications, while ordinary carbon steel fails at 300°C.

 

To Meet Mandatory Compliance

Grades help buyers adhere to global standards like ASTM, EN, and JIS, as well as industry-specific regulations—such as ASTM A516 for pressure vessels. If buyers use non-compliant steel (e.g., uncertified grades in aerospace or nuclear projects), they may face legal penalties or project shutdowns, as noted by the Cabaro Group. Buyers must also verify Material Test Reports (MTRs), which confirm grade-specific characteristics—such as EN 10025-2 S355JR’s ability to withstand impact at -20°C—to ensure alignment with building codes or safety mandates.

 

To Optimize Cost Efficiency

Grades prevent buyers from wasting funds. Over-specifying—for instance, using 316 stainless steel for a dry warehouse—adds 20–30% to material costs. Under-specifying (e.g., using low-carbon steel for a coastal bridge) doubles replacement expenses within five years, per Hamasteel data. A grade’s total lifecycle cost (initial price plus maintenance) often matters more than upfront savings. For example, ASTM A572 Grade 50 (with a 50 ksi tensile strength) costs 15% more than A36 but lasts three times longer in high-stress structures.

 

What Are the Main Types of Steel Grade Systems?

Steel grade systems are standardized frameworks that organize the over 3,500 different steel grades (per Econsteel’s How to Read Steel Grades) by composition, properties, and use—eliminating industry confusion and ensuring consistent communication between buyers, manufacturers, and engineers. These systems are developed by global or regional organizations, each with unique coding rules tailored to specific markets.

 

In the global steel grade system, there are four main types of standards that support most purchasing needs.

 

1. ASTM International Steel Grade System

Developed by the American Society for Testing and Materials (ASTM), this system is one of the most comprehensive globally, with around 12,000 unique codes covering metals (including steel). As Econsteel notes, its structure prioritizes clarity for cross-industry use:

• Prefix rules: The letter “A” is exclusively used for iron and steel (e.g., “ASTM A36”); other letters (like “B” for non-ferrous metals) apply to other materials.
• Numerical codes: The number after the prefix identifies specific properties and applications, not just a random label.
• Core purpose: ASTM sets manufacturing and product standards across industries, ensuring steel meets safety and performance requirements for applications like construction, aerospace, and pressure vessels.

 

ASTM Grade Code	Key Properties	Typical Applications
ASTM A36	Tensile strength: 58–80 ksi; Yield strength: ≥36 ksi; High weldability	Structural components (e.g., beams, columns), construction framing, simple machine parts
ASTM A516	Tensile strength: 60–85 ksi; Yield strength: ≥30 ksi; Excellent pressure resistance	Pressure vessels (e.g., oil tanks, boilers), petrochemical industry equipment
ASTM A572	Tensile strength: 65–90 ksi; Yield strength: 50–65 ksi (varies by grade); High-strength low-alloy (HSLA)	Heavy-duty structural parts (e.g., bridge girders, large building frames), load-bearing supports
ASTM A514	Tensile strength: ≥110 ksi; Yield strength: ≥90 ksi; High-impact resistance	Wear-resistant components (e.g., crane booms, mining machinery parts), high-load structures
ASTM A351	Tensile strength: 70–100 ksi (varies by alloy); Austenitic stainless steel base; Corrosion resistance	Cast steel parts (e.g., valve bodies, pump housings), industrial machinery cast components
ASTM A106	Tensile strength: 60–80 ksi; Yield strength: ≥30 ksi; Seamless pipe design	Carbon steel pipes (e.g., oil/gas transmission lines, water supply pipes), industrial piping systems

 

2. AISI/SAE Steel Grade System

Jointly developed by the American Iron and Steel Institute (AISI) and Society of Automotive Engineers (SAE), this system focuses exclusively on steel (unlike ASTM, which covers all metals)—a key detail highlighted in Econsteel’s How to Read Steel Grades. It’s widely used in North America and global industries like automotive and machinery, thanks to its simple, property-focused coding. Key rules for understanding the system:

• Four-digit code structure: The core of the system, with each pair of digits carrying a specific meaning.
• First two digits: Indicate steel type and main alloying elements (e.g., “10” = plain carbon steel, “41” = chromium-molybdenum steel).
• Last two digits: Represent carbon content, measured in hundredths of a per cent (e.g., “20” = 0.20% carbon, “45” = 0.45% carbon).

 

AISI/SAE Grade Code	Key Properties	Typical Applications
1018	Carbon content: 0.18%; Tensile strength: 60 ksi; Yield strength: 44 ksi; High ductility	Automotive stampings (e.g., brackets, clips), low-stress machine parts, fasteners
1045	Carbon content: 0.45%; Tensile strength: 90 ksi; Yield strength: 70 ksi; Good hardenability	Medium-stress components (e.g., gears, shafts, bolts), tool holders, and mechanical couplings
1340	Carbon content: 0.40%; Manganese-alloyed (1.60–1.90%); Tensile strength: 120 ksi	Heavy-duty parts (e.g., truck axles, crankshafts, industrial gears), high-torque components
4140	Carbon content: 0.40%; Chromium-molybdenum alloy; Tensile strength: 110 ksi; Heat-treatable	Precision parts (e.g., hydraulic cylinders, aircraft landing gear components, drill bits), high-wear shafts
4340	Carbon content: 0.40%; Nickel-chromium-molybdenum alloy; Tensile strength: 140 ksi; High impact resistance	Critical load parts (e.g., turbine shafts, aerospace structural components, racing engine parts)
8620	Carbon content: 0.20%; Nickel-chromium-molybdenum alloy; Tensile strength: 80 ksi; Carburizable	Surface-hardened parts (e.g., gear teeth, camshafts, bearing races), automotive transmission components

 

3. EN Steel Grade System

Developed by the European Committee for Standardization (CEN), the EN (European Norm) system is mandatory across the European Union (EU) and widely adopted in global industrial sectors—from construction to energy. Unlike simpler numerical systems, its coding combines letters and numbers to clearly signal steel’s use, strength, and environmental resistance, a design highlighted in industry guides like Econsteel’s. Key rules for decoding:

• “EN” prefix: Marks compliance with European standards (e.g., “EN 10025” for structural steel).
• Standard number: Follows the prefix to define steel category (e.g., “EN 10025-2” = hot-rolled structural steel, “EN 10216-2” = seamless steel tubes for pressure).
• Grade code: A mix of letters + numbers + suffixes:
  • First letter = use (e.g., “S” = structural steel, “P” = pressure vessel steel, “X” = stainless steel).
  • Middle numbers = minimum yield strength (e.g., “355” = ≥355 MPa yield strength).
  • Suffix = impact toughness (e.g., “JR” = room-temperature impact resistance, “NL” = low-temperature toughness).

 

EN Grade Code	Key Properties	Typical Applications
EN 10025-2 S355JR	Yield strength: ≥355 MPa; Tensile strength: 470–630 MPa; Room-temperature impact resistance (JR); Weldable	Civil engineering (e.g., building frames, bridges), heavy machinery bases, and structural steel plates
EN 10216-2 P265GH	Yield strength: ≥265 MPa; Tensile strength: 410–530 MPa; High-temperature resistance (up to 500°C); Pressure-resistant	Boiler tubes, heat exchangers, industrial pressure vessels (e.g., chemical reactors)
EN 10088-1 X5CrNi18-10	Austenitic stainless steel; Yield strength: ≥205 MPa; Tensile strength: ≥520 MPa; Excellent corrosion resistance	Food processing equipment, chemical tanks, architectural trim, and medical instruments (equivalent to 304 stainless steel)
EN 10113-2 S460ML	Yield strength: ≥460 MPa; Tensile strength: 570–720 MPa; Low-temperature impact resistance (down to -40°C); High weldability	Offshore structures (e.g., oil platforms), large-scale bridges, and wind turbine towers
EN 10297-1 E355	Yield strength: ≥355 MPa; Tensile strength: 490–630 MPa; Seamless tube-specific; Good formability	Oil/gas transmission pipes, water supply pipelines, industrial fluid transport tubes
EN 10088-1 X2CrNiMo17-12-2	Duplex stainless steel; Yield strength: ≥270 MPa; Tensile strength: ≥580 MPa; High corrosion resistance (saltwater, chemicals)	Marine components (e.g., ship hulls), desalination plants, offshore oil rig equipment (equivalent to 316L stainless steel)

 

4. JIS Steel Grade System

Developed by the Japanese Industrial Standards Committee (JISC), the JIS (Japanese Industrial Standards) system is the core steel grading framework for Japan and widely used in East Asian markets (e.g., South Korea, Taiwan)—especially in automotive, electronics, and precision manufacturing. Its design prioritizes simplicity and direct alignment with industrial needs, with coding that combines prefixes, standard numbers, and grade labels to clarify steel type and purpose. Key rules for decoding:

• “JIS” prefix + category letter: The letter after “JIS” defines the material group—“G” exclusively for iron and steel (e.g., “JIS G3101” = structural carbon steel, “JIS G4305” = stainless steel plates).
• Standard number: Follows the category letter to specify the steel’s form or use (e.g., “JIS G3452” = seamless steel tubes, “JIS G3116” = high-strength structural steel).
• Grade code: A mix of letters and numbers, where letters signal use (e.g., “SS” = structural steel, “SUS” = stainless steel) and numbers indicate key properties (e.g., strength, carbon content).

 

JIS Grade Code	Key Properties	Typical Applications
JIS G3101 SS400	Tensile strength: ≥400 MPa; Yield strength: ≥245 MPa; Low carbon (≤0.25%); High weldability	General structural parts (e.g., building beams, truck frames), simple machine casings, and non-load-bearing components
JIS G4305 SUS304	Austenitic stainless steel; Tensile strength: ≥520 MPa; Yield strength: ≥205 MPa; Excellent corrosion resistance (no magnetic)	Kitchen appliances (e.g., sinks, ovens), food processing equipment, electronic device casings, architectural trim
JIS G3452 STK400	Tensile strength: ≥400 MPa; Yield strength: ≥245 MPa; Seamless tube-specific; Good formability	Industrial piping (e.g., water pipes, air ducts), automotive exhaust tubes, light-duty fluid transport systems
JIS G3116 SM490A	High-strength structural steel; Tensile strength: ≥490 MPa; Yield strength: ≥325 MPa; Weldable; Impact resistance (room temperature)	Heavy machinery frames, bridge components, large-scale construction steel (e.g., stadium structures)
JIS G3106 SN490B	Bridge-specific structural steel; Tensile strength: ≥490 MPa; Yield strength: ≥325 MPa; Low-temperature impact resistance (down to -5°C)	Highway bridges, railway bridges, offshore platform support structures
JIS G3204 SCM440	Chromium-molybdenum alloy steel; Tensile strength: ≥800 MPa; Yield strength: ≥600 MPa; Heat-treatable; High wear resistance	Precision mechanical parts (e.g., gears, shafts, hydraulic valves), automotive engine components, and tool holders

 

5. Other Steel Grade Systems

Beyond the four core global steel grade frameworks covered earlier, there are several regional-specific systems tailored to local needs—such as high-salt coastal environments, key industries (e.g., automotive, infrastructure), or legacy manufacturing practices. While these systems primarily serve their respective regions, they play a critical role in local trade, domestic projects, and the maintenance of existing equipment. Below is a summary of major regional steel grade systems not previously highlighted:

 

Regional Steel Grade System	Introduction	Grade Examples
AS/NZS Steel Grade System (Australia & New Zealand)	Developed jointly by Standards Australia and Standards New Zealand, it emphasizes “coastal corrosion resistance” and “high-strength for infrastructure” to match the regions’ extensive coastlines and large-scale engineering projects.	AS/NZS 3679.1 Grade 350 (steel for coastal bridges, 350 MPa yield strength, seawater corrosion resistance); AS/NZS 1594 Grade 300 (structural steel for residential and commercial building frames)
DIN Steel Grade System (Germany, Legacy Use)	Former national standard of Germany (developed by Deutsches Institut für Normung). Most standards have now been integrated into the EN system, but it remains in use for “legacy projects” like old factory maintenance and vintage equipment repairs.	DIN 17100 St37-2 (traditional structural steel, 37 MPa tensile strength, used for old factory equipment frames); DIN 17440 X5CrNi18-10 (legacy stainless steel standard, equivalent to EN 304, used for old food machinery)
GB Steel Grade System (China)	Established by the Standardization Administration of China (SAC), it covers all steel categories and is tailored to China’s infrastructure, automotive, and machinery manufacturing needs. It is the mandatory/recommended core standard for the Chinese market.	GB/T 700 Q235B (carbon structural steel, 235 MPa yield strength, used for factory columns and general mechanical parts); GB/T 3280 06Cr19Ni10 (food-grade stainless steel, equivalent to 304, used for kitchenware and medical equipment)
KS Steel Grade System (South Korea)	Created by the Korean Standards Association (KSA), it is optimized for South Korea’s automotive (e.g., Hyundai, Kia) and electronics industries. Some standards reference JIS but include enhancements for “precision machining.”	KS D 3501 SM490A (high-strength structural steel, 490 MPa tensile strength, used for automotive frames); KS D 1621 STS304 (stainless steel sheet, used for electronic device casings with high flatness requirements)
IS Steel Grade System (India)	Developed by the Bureau of Indian Standards (BIS), it supports India’s “infrastructure-first strategy,” focusing on “low cost and high adaptability” for small-to-medium construction and agricultural machinery.	IS 2062 E250A (general structural steel, 250 MPa yield strength, used for rural school buildings and small bridges); IS 1570 Grade Fe 415 (steel for reinforcing bars, 415 MPa tensile strength, used for residential infrastructure)

 

What Steel Grades Fit Common Applications?

Choosing the right steel grade matters—it balances performance, durability, and cost. The decision depends on three key things: first, what the steel will be used for (application needs); second, measurable performance specs (like strength or corrosion resistance); third, following industry standards.

 

For example, structural projects need steel with high weldability. Marine or chemical work needs steel that resists corrosion. Picking the wrong grade can risk safety or equipment failure.

 

Below is a simple breakdown of recommended steel grades for common uses.

Common Applications	Recommended Steel Grades
Structural Fabrication	ASTM A36	EN S275JR	JIS SS400
Powertrain/Shafts/Gears	AISI 1045	AISI 4140	JIS SCM440
Tooling/High-Temperature	AISI H13	ASTM 4140H	EN X40CrNiMoV5-1
Marine/Chemical Industries	AISI 316L	Duplex 2205	EN X2CrNiMo17-12-2
Food/Medical Equipment	AISI 304L	EN X5CrNi18-10	JIS SUS304
Pressure Vessels/Piping	ASTM A516 Gr.70	EN P265GH	ASTM A106 Gr.B

 

Conclusion

Steel grades serve as the industry’s universal “technical language,” condensing chemical composition, mechanical properties, and application suitability into clear identifiers. They offer three vital benefits to buyers: reliable performance (e.g., AISI 4140’s tensile strength of ≥110 ksi for powertrain parts, 316L’s resistance to saltwater corrosion for marine use), regulatory compliance (aligning with global standards like ASTM, EN, or JIS to prevent legal risks in sectors such as aerospace or nuclear), and cost optimization (e.g., ASTM A572 Grade 50 costs 15% more than ASTM A36 but lasts three times longer in high-stress structures). Whether selecting from global systems (ASTM for North America, EN for Europe) or regional frameworks (GB for China, AS/NZS for Australia/New Zealand), the core principle remains: matching steel grades to specific application needs. By following the data-driven guidance in this blog, buyers can choose steel grades that balance performance, compliance, and cost, avoiding project delays, safety hazards, or wasted resources from misselection.

 

Conclusion

Steel grades act as the industry’s “common language,” distilling chemical composition, mechanical properties, and application fit into clear identifiers. They deliver three critical benefits for buyers: reliable performance, regulatory compliance, and cost optimisation.

 

Whether selecting from global systems or regional frameworks, matching grades to application needs—structural vs. marine, for example—remains essential. By using the data-driven guidance here, buyers can choose steel grades that balance performance, compliance, and cost, avoiding project delays or safety risks from misselection.