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

Steel grades are standardized classifications outlining steel’s chemical composition, mechanical properties, and intended applications.

A key point to understand when exploring steel grades is that their primary distinction lies in systematic classification, not inherent superiority. Just as the value of a water source depends on context rather than a universal standard, no single steel grade or grade system is “better” by default—what matters is alignment with specific needs. Globally, four core systems dominate, plus regional frameworks. Each uses unique coding rules to communicate critical details clearly.

Neither tap nor bottled water is inherently safer; similarly, neither one steel grade nor system is inherently more reliable. The differences between them stem from how each system’s classification aligns with three factors: application requirements, performance specifications, and regulatory standards. Choosing the right steel grade is therefore not a straightforward decision—it requires understanding how these elements intersect. The section below breaks down steel grade basics, key systems, and application-focused recommendations to simplify this critical decision for buyers, engineers, and suppliers.

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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?
• Conclusão

What Are Steel Grades?

Steel grades classify steel by its chemical composition, mechanical properties, and industrial uses. They indicate factors like carbon content. Low-carbon steels have around 0.05% carbon, while high-carbon alloys have more than 1.5%, as noted in Wikipedia’s Steel Grades entry. Grades also specify alloying elements, such as chromium for corrosion resistance and nickel for toughness. They include mechanical limits like tensile strength (measured in MPa or ksi) and yield strength.

These grades follow global standards. ASTM is for North America, EN for Europe, and JIS for Asia. This creates a consistent benchmark for manufacturers.

As EconSteel’s How to Read Steel Grades notes, this system removes confusion. A grade tells you if a steel is right for structural framing, pressure vessels, or automotive parts. Steel grades simplify complex chemical, mechanical, and regulatory details into one identifier. They act as the common language of the industry. This ensures that buyers, engineers, and suppliers understand each other clearly.

Why Do Steel Grades Matter For Buyers?

Steel grades are important for buyers. They remove the guesswork from selecting steel. Grades ensure that purchases meet functional requirements, follow local regulations, and fit within budget. This helps avoid costly mistakes and saves resources. Without clear grades, buyers risk choosing steel that is too weak, doesn’t meet safety standards, or leads to extra costs. These issues can delay projects or cause major problems later.

To Secure Reliable Performance

Grades define how steel performs. For instance, ASTM A36 steel has a tensile strength of 58–80 ksi. 316 stainless steel has better corrosion resistance in saltwater due to its molybdenum content, as noted in Viraj’s analysis. Choosing the wrong grade, like low-yield steel for a crane beam, can lead to structural failure. Ignoring chromium content in a chemical plant can cause faster deterioration. Grades also show steel’s heat tolerance. EN 10216-2 P265GH can handle temperatures above 500°C for boilers, while regular carbon steel fails at 300°C.

To Meet Mandatory Compliance

Grades help buyers meet global standards, including ASTM, EN, and JIS. They follow specific rules, such as ASTM A516 for pressure vessels. Using non-compliant steel, like uncertified grades in aerospace or nuclear projects, can lead to legal penalties or project shutdowns. Buyers must check Material Test Reports (MTRs) that confirm grade-specific traits. For example, EN 10025-2 S355JR can handle impacts at -20°C. This ensures compliance with building codes and safety requirements.

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 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 classify over 3,500 steel grades (Econsteel). They do this by organizing grades based on composition, properties, and use. This reduces confusion in the industry and ensures clear communication among buyers, manufacturers, and engineers. Different global and regional organizations create these systems. Each has its own coding rules for specific markets.

In the global steel grade system, there are four main types of standards. These standards cover 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. As Econsteel’s How to Read Steel Grades 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

• AISI/SAE Steel Grade System

The AISI/SAE system focuses only on steel. Developed by the American Iron and Steel Institute (AISl) and Society ofAutomotive Engineers (SAE), it is widely used in North America and in global industries such as automotive and machinery. 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 percent (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, 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

• EN Steel Grade System

EN (European Norm) system is developed by the European Committee for Standardization (CEN). It is mandatory across the European Union (EU) and widely used in global industrial sectors—like construction and energy.

Unlike simpler numerical systems, its coding uses letters and numbers. This clearly signals steel’s use, strength, and environmental resistance. 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, 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, 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, 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)

• JIS Steel Grade System

JIS (Japanese Industrial Standards) system is developed by the Japanese Industrial Standards Committee (JISC). It is the core steel grading framework for Japan and widely used in East Asian markets—such as South Korea and Taiwan. It is especially common in automotive, electronics, and precision manufacturing sectors.

Its design prioritizes two key points: simplicity and direct alignment with industrial needs. Its coding combines three elements—prefixes, standard numbers, and grade labels. This combination clarifies two things: steel type and steel 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, 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, tool holders

5. Other Steel Grade Systems

Beyond the four core global steel grade frameworks covered earlier, there are several regional-specific systems. These systems are tailored to local needs.

Local needs include high-salt coastal environments, key industries (e.g., automotive, infrastructure), and legacy manufacturing practices.

These systems mainly serve their respective regions. But they still play a critical role—supporting 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. Three key elements drive the decision of steel grade selection: first, application needs—meaning what the steel will be used for; second, quantifiable performance specs—such as strength or corrosion resistance; third, compliance with 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

Conclusão

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

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.