ASTM A36 vs S355 Steel — Cross-Standard Equivalents and Selection

This article provides general technical reference. Structural steel grade selection should be verified against the applicable building code, design standard, project specification and the supplied mill certificate.

ASTM A36 and EN 10025-2 S355 are two of the most widely specified structural carbon steels in the world. They appear in buildings, bridges, industrial plants, ships and heavy machinery on every continent. For engineers, fabricators and procurement professionals working across regional standards, understanding how they compare — and where they cannot be treated as interchangeable — is essential.

Both grades sit in the same broad family of low-carbon structural steels suitable for welding and general fabrication. They are defined under different standards systems (ASTM for North America, EN 10025 for Europe and regions adopting European codes), they specify mechanical properties in different ways, and they treat impact toughness differently. A direct grade-for-grade substitution is rarely appropriate without engineering review.

This article compares the two grades by standard designation, chemical composition, mechanical properties, impact toughness, weldability, applications and certification, and provides a selection framework for the most common industrial scenarios.

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ASTM A36 — Standard, Composition and Properties

ASTM A36/A36M ¹ is the historic general-purpose structural steel of the American system. Published by ASTM International, it covers carbon steel shapes, plates and bars intended for use in bolted, welded or riveted structural construction. The “36” in the designation refers to the minimum yield strength of 36 ksi, equivalent to approximately 250 MPa. A36 is also recognised as the North American equivalent under ISO 630 ² in the grade designation “S235”.

The standard applies to a wide range of product forms:

• Structural shapes (W, S, M, HP, C, L shapes) per ASTM A6
• Plates and bars up to 8 inches (200 mm) in thickness
• Wide-flange sections, channels, angles and tees

Chemical Composition (ASTM A36/A36M)

Element	Content (typical, ladle analysis)
Carbon (C)	≤ 0.25 % (≤ 0.29 % for some shapes and thicknesses)
Manganese (Mn)	0.80 – 1.20 % (varies by thickness)
Silicon (Si)	≤ 0.40 %
Phosphorus (P)	≤ 0.040 %
Sulfur (S)	≤ 0.050 %
Copper (Cu)	≥ 0.20 % when specified for atmospheric corrosion resistance

A36 is supplied as a non-alloyed carbon steel with a ferrite-pearlite microstructure. Carbon is intentionally kept low to maintain good weldability and formability.

Mechanical Properties (ASTM A36/A36M)

Property	Value
Minimum yield strength	250 MPa (36 ksi)
Tensile strength	400 – 550 MPa (58 – 80 ksi)
Minimum elongation (in 200 mm)	20 %
Minimum elongation (in 50 mm)	23 %
Mandatory Charpy impact test	Not required in basic specification

Yield and tensile values are the same across the full product range covered by the standard. Elongation requirements are thickness-dependent.

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EN 10025-2 S355 — Designation, Composition and Properties

EN 10025-2 ³ is part of the European EN 10025 series for hot-rolled structural steel products. It covers the non-alloy quality steels S235, S275 and S355 in delivery conditions “+AR” (as-rolled) or “+N” (normalized). S355 is the highest strength grade in the S235–S275–S355 family and is the dominant European structural grade for primary load-bearing members.

The designation is decoded as follows:

• S — Structural steel
• 355 — Minimum specified yield strength in MPa, for thicknesses up to 16 mm
• JR / J0 / J2 / K2 — Charpy V-notch impact toughness subgrade

The mechanical properties of S355 are thickness-dependent. Yield strength decreases as thickness increases, because thicker sections cool more slowly during rolling and develop a less fine-grained microstructure.

Chemical Composition (EN 10025-2 S355, ladle analysis, ≤ 16 mm)

Element	Content
Carbon (C)	≤ 0.20 % (≤ 0.22 % for 16–40 mm)
Manganese (Mn)	≤ 1.60 %
Silicon (Si)	≤ 0.55 %
Phosphorus (P)	≤ 0.025 – 0.030 %
Sulfur (S)	≤ 0.025 – 0.030 %
Nitrogen (N)	≤ 0.012 %
Copper (Cu)	≤ 0.55 %
Carbon equivalent value (CEV)	≤ 0.45 % (≤ 0.47 % for thicker sections)

The tighter control of sulfur, phosphorus and nitrogen compared with A36 contributes to better notch toughness and weldability.

Mechanical Properties (EN 10025-2 S355)

Property	Thickness ≤ 16 mm	16 – 40 mm	40 – 63 mm	63 – 80 mm
Minimum yield strength (MPa)	355	345	335	325
Tensile strength (MPa)	470 – 630	470 – 630	470 – 630	470 – 630
Minimum elongation (%)	22	22	22	21
Charpy impact (27 J minimum)	Subgrade-dependent	Subgrade-dependent	Subgrade-dependent	Subgrade-dependent

For S355K2, the impact test requirement extends to -40 °C, providing additional toughness reserve for cold-climate and offshore service.

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Chemical and Mechanical Properties Side-by-Side

The following table summarizes the principal differences in chemistry and mechanical performance between the two grades.

Parameter	ASTM A36	EN 10025-2 S355 (≤ 16 mm)
Standard	ASTM A36/A36M	EN 10025-2
Yield strength (min)	250 MPa	355 MPa
Tensile strength range	400 – 550 MPa	470 – 630 MPa
Carbon (max)	0.25 %	0.20 %
Manganese (range)	0.80 – 1.20 %	≤ 1.60 %
Sulfur (max)	0.050 %	0.025 – 0.030 %
Phosphorus (max)	0.040 %	0.025 – 0.030 %
Carbon equivalent (CEV)	Typically ≤ 0.40	≤ 0.45
Mandatory impact test	No	Yes (subgrade dependent)
Impact subgrades	None	JR / J0 / J2 / K2

Two practical observations follow from this comparison:

1. S355 provides higher strength per unit weight. A 355 MPa yield allows approximately 30 % more design stress than a 250 MPa yield, which can translate into thinner plates, lighter members and reduced structural weight.
2. S355 has tighter chemistry limits. Lower sulfur and phosphorus, combined with mandatory impact testing, give more consistent through-thickness properties — particularly important for thick sections and low-temperature service.

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Impact Toughness: Understanding JR, J0 and J2

One of the most important practical differences between ASTM A36 and EN 10025-2 is the treatment of impact toughness. Impact toughness measures a steel’s ability to absorb energy under sudden loading, particularly at lower temperatures. For welded structures, bridges, offshore platforms and any installation in cold climate, impact toughness is often the limiting design parameter.

EN 10025 Impact Designations

The suffix after the S355 grade designation indicates the Charpy V-notch impact test condition:

Grade	Charpy impact energy	Test temperature
S235JR / S275JR / S355JR	27 J	+20 °C
S235J0 / S275J0 / S355J0	27 J	0 °C
S235J2 / S275J2 / S355J2	27 J	-20 °C
S355K2	40 J	-20 °C (-40 °C option exists for some thicknesses)

The “27 J” reference comes from a standardized Charpy V-notch specimen tested on a pendulum impact machine. Higher numbers mean more energy absorbed before fracture, indicating greater toughness.

For projects exposed to cold climate, dynamic loading or fatigue-sensitive service, specifying the J2 or K2 subgrade is standard practice. The K2 subgrade in particular is used for offshore structures and cold-region infrastructure.

ASTM A36 Impact Requirements

ASTM A36 does not include a mandatory Charpy impact requirement in its basic specification. For many general structural applications, this is acceptable because the carbon equivalent is low and the operating temperature is moderate.

However, project specifications commonly add supplementary impact requirements — particularly for:

• Cold-climate structures
• Offshore or marine environments
• Dynamically loaded members
• Welded details subject to fatigue

Where supplementary Charpy testing is required, it is typically specified as a project-specific supplementary requirement (S5, S6 or S8 in ASTM A6/A6M terminology, for example), with the test temperature and acceptance energy stated in the purchase specification.

In practice, this means that an A36 steel can be supplied with verified Charpy values when specified — but it must be requested at the procurement stage. EN 10025-2 makes this mandatory by default for every delivery.

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Weldability and Fabrication

Both A36 and S355 are readily weldable using the standard arc-welding processes — SMAW (shielded metal arc), GMAW (gas metal arc), FCAW (flux-cored arc) and SAW (submerged arc). Preheat requirements are governed primarily by the carbon equivalent value (CEV), the combined thickness of the joint and the hydrogen level of the consumable.

Parameter	ASTM A36	EN 10025-2 S355
Typical CEV	≤ 0.40	≤ 0.45 (≤ 0.47 for thick sections)
Preheating requirement (typical)	Generally none for thin sections	Generally none for thin sections; preheat recommended for CEV > 0.45 or thick sections
Hydrogen control	Standard consumables acceptable	Low-hydrogen consumables recommended for thick sections
Cold cracking risk	Low	Low to moderate, depending on restraint and CEV

For thin-plate applications (≤ 16 mm), the two grades can be welded using essentially the same procedure. For thick sections and highly restrained joints, S355 may require controlled heat input and preheating to avoid hydrogen-assisted cracking, particularly at higher CEV.

Formability is similar. Both grades can be cold-formed, hot-formed and flame-cut using standard workshop practice. S355 has marginally higher spring-back because of its higher yield strength — relevant when tight forming radii are specified.

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Application Differences

ASTM A36

A36 is the general-purpose structural steel of the American system. It is most commonly selected where moderate strength, good availability and proven weldability are the dominant requirements. Typical applications include:

• Buildings — beams, columns, base plates, gusset plates
• Warehouses and industrial sheds
• Bridges (secondary members, gussets, bracing)
• Machinery frames and equipment supports
• Storage tanks and general fabrication
• Architectural metalwork

A36 is widely available in standard sections (W-shapes, channels, angles) and plates. It is the default “go-to” grade for North American structural projects that do not require higher strength.

EN 10025-2 S355

S355 is the dominant grade for primary structural members in modern European construction. Its higher yield strength allows more efficient section sizing and weight reduction in long-span and high-load applications. Typical uses include:

• Heavy machinery structures and equipment frames
• Industrial plants, refineries and process structures
• Bridge girders and primary members
• Offshore platforms and marine structures
• Crane runways and gantry structures
• Transportation structures (railway bridges, port equipment)

In many modern European building standards, S355 has effectively replaced S275 as the default grade for primary members. For seismic-resistant design, the combination of S355 with appropriate detailing per EN 1998 (Eurocode 8) is widely used.

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Selection Framework

The choice between A36 and S355 depends on the design code in force, the strength required and the procurement region. The table below summarizes the principal decision points.

Scenario	Recommended starting grade
General structural fabrication in North America	A36
General structural fabrication in Europe	S275JR or S355JR
Higher strength primary members (North America)	A572 Grade 50 or A992
Higher strength primary members (Europe)	S355JR / S355J0 / S355J2
Cold-climate or offshore structures	S355J2 or S355K2 (or A36 with supplementary impact requirements)
Heavy machinery structures	S355 (A36 only for lighter duty)
Bridge primary members	S355 (A36 acceptable for secondary members)
International projects requiring EN certification	S355 with EN 10204 3.1
Existing A36 design basis, no upgrade	A36

A useful rule of thumb:

• A36 is roughly comparable to S235JR in strength, not to S355.
• S355JR is roughly comparable to A572 Grade 50 and A992.

For design calculations, the relevant standard (AISC 360 ⁴ in the US, EN 1993-1-1 ⁵ in Europe) should be used. The grade designation alone is not a substitute for design verification.

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Substitution Considerations

International procurement often involves requests for “equivalent” grades. Substitution between A36 and S355 should always be reviewed against more than the yield strength number.

Substituting S355 for A36

Because S355 is the stronger grade, substitution is feasible from a strength standpoint. However:

• Welding procedure qualification may need updating if preheat and heat-input limits change.
• Impact requirements must be carried over (J2 or K2 subgrade for cold service).
• Certification documentation changes from ASTM to EN format and must be re-verified.
• Bolt specifications (e.g. ASTM A325/A490 vs EN 14399) and connection detailing standards differ.

A stronger steel is not automatically a direct replacement. Engineering review is required.

Substituting A36 for S355

The reverse substitution is generally more constrained. Because A36 has lower yield strength, design capacity reduces. The substitution typically requires:

• Re-running member sizing calculations
• Re-checking deflection and stability criteria
• Verifying weld and bolt group capacity at lower material strength
• Potentially redesigning the connection or member

A36 should not replace S355 without formal engineering approval.

Cross-Standard Equivalents (for Reference Only)

Standard system	Comparable grade	Notes
ASTM	A36	250 MPa yield, no mandatory impact
EN 10025-2	S235JR	Closest European equivalent in strength
EN 10025-2	S355JR	Higher strength (≈ A572 Gr 50)
GB/T 700	Q235B	Chinese equivalent of A36 / S235JR
GB/T 1591	Q355B	Chinese equivalent of S355JR 6
JIS G3101	SS400	Japanese equivalent of A36 / S235

These equivalences are approximate. For project specifications, the actual standard cited on the mill certificate should be used, not the assumed equivalence.

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Certification and Documentation

For international structural steel supply, the certification document is as important as the grade designation. The most widely used reference for inspection documents is EN 10204 ⁷, which defines four common certificate types:

Certificate	Description
EN 10204 2.1	Declaration of compliance with the order
EN 10204 2.2	Test report based on non-specific inspection
EN 10204 3.1	Inspection certificate with actual test results, issued by the mill
EN 10204 3.2	Certificate with third-party inspection

For most international structural projects, EN 10204 3.1 is the standard minimum requirement. It is issued by the mill’s quality department and validated by an independent inspector who is not part of the production team. EN 10204 3.2 adds a second independent signatory (typically a third-party inspection agency) and is required for some offshore, nuclear and high-risk applications.

A complete mill certificate should include:

• Manufacturer identification and address
• Product form, dimensions and quantity
• Heat number and cast number
• Chemical composition (heat analysis and product analysis where applicable)
• Mechanical test results (yield, tensile, elongation, impact)
• Applicable standard and grade designation
• Heat treatment condition (as-rolled, normalized, etc.)
• Statement of compliance and authorized signature

For more detail on certificate types, see EN 10204 Mill Certificates Explained.

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Procurement Specifications

When sourcing A36 or S355 internationally, the purchase specification should include the following items:

• Material grade — for example, “ASTM A36/A36M” or “EN 10025-2 S355J2”.
• Product form — plate, sheet, section, bar, hollow section.
• Thickness and dimensional tolerances — per the product standard (ASTM A6, EN 10010021 or equivalent).
• Yield strength class — explicit confirmation of the class, including thickness-dependent adjustment for S355.
• Impact toughness subgrade — JR, J0, J2 or K2 for EN grades; supplementary requirements for ASTM if Charpy values are needed.
• Certification — EN 10204 certificate type, third-party inspection requirement.
• Surface condition — hot-rolled with mill scale, shot-blasted and primed, galvanized, painted.
• Length and cutting — cut-to-size, fixed length, multiple lengths.

For EN grades, the thickness effect on yield strength must be specified explicitly. An order for “S355 plate 25 mm” requires confirmation that the supplier is delivering material meeting the 16–40 mm class yield requirement of 345 MPa — not the 355 MPa class applicable only to ≤ 16 mm thickness.

For ASTM A36, the standard does not reduce yield strength with thickness across its scope, but practical considerations (heat number, plate width, normalizing) should be reviewed for thick sections.

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Quick Selection Table

Requirement	Recommended grade
General structural fabrication, North America	A36
General structural fabrication, Europe	S235JR or S355JR
Higher strength required	S355JR / A572 Grade 50
Cold-climate or low-temperature service	S355J2 or S355K2
Offshore or marine exposure	S355K2 (or A36 with supplementary impact)
Heavy machinery structures	S355
Bridge primary members	S355 (Europe) / A572 Gr 50 (North America)
International procurement with EN certification	S355 + EN 10204 3.1
International procurement with ASTM certification	A36 + ASTM A6 supplementary requirements
Replacement of A36 with higher strength	S355JR (after engineering review)

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Conclusion

ASTM A36 and EN 10025-2 S355 are both important structural carbon steel grades, but they belong to different strength classes and different standards systems. A36 offers a minimum yield strength of 250 MPa with no mandatory impact requirement and broad availability in standard North American sections. S355 offers a minimum yield strength of 355 MPa (for ≤ 16 mm), mandatory Charpy impact testing at a specified subgrade temperature, tighter chemistry limits and broader thickness coverage.

In practice, A36 is most often compared with S235JR (similar strength) rather than with S355. S355JR is most often compared with A572 Grade 50 or A992. Substitution between A36 and S355 should always be reviewed against design code, weld procedure, certification format and impact requirements — not just yield strength.

For international procurement, the most reliable approach is to specify the actual standard, grade and subgrade on the purchase order, verify the mill certificate against the specification on receipt, and confirm that the supplier’s quality system can consistently meet the required documentation level.

For a broader overview of structural steel grades and their regional standards, see Structural Steel for Building Construction — Standards and Grades. For background on how plate is specified and supplied, see Steel Plate for Industrial Applications — Specifications and Procurement.

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Frequently Asked Questions

Is ASTM A36 the same as S355?

No. A36 and S355 belong to different strength classes. A36 specifies a minimum yield strength of 250 MPa, while S355JR specifies 355 MPa for thicknesses up to 16 mm. A36 is more closely comparable to EN S235JR; S355JR is more closely comparable to A572 Grade 50.

Can S355 replace ASTM A36?

S355 may be considered as an alternative to A36 because it provides higher strength. The substitution requires reviewing structural design, welding procedure qualification, certification format and impact toughness requirements. The supplied material must be certified as S355 to EN 10025-2, not described as “A36 equivalent.”

Can ASTM A36 replace S355?

Generally not without engineering review. A36 has lower yield strength than S355, so structural capacity is reduced. Member sizing, deflection and connection design may need to be repeated. A36 should not replace S355 in primary load-bearing members without formal engineering approval.

What is the Chinese equivalent of ASTM A36?

Q235B under GB/T 700 is commonly compared with ASTM A36. The chemical composition, mechanical requirements and certification system differ, so buyers should confirm the actual standard stated on the mill certificate rather than relying on the assumed equivalence.

What is the Chinese equivalent of S355?

Q355B under GB/T 1591 ⁶ is commonly compared with EN S355JR. As with any cross-standard equivalence, the mill certificate should confirm the actual standard, grade and subgrade before the material is accepted.

What certificate should be requested for structural steel?

For most international projects, EN 10204 3.1 ⁷ is the standard minimum requirement. The certificate must include the material grade, heat number, chemical analysis, mechanical test results and the applicable standard. For high-risk or third-party-inspected projects, EN 10204 3.2 is required.

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References

1. ASTM International, ASTM A36/A36M — Standard Specification for Carbon Structural Steel. ASTM A36 ↩

2. International Organization for Standardization, ISO 630-1:2021 — Structural steels — Part 1: General technical delivery conditions. ISO 630 ↩

3. European Committee for Standardization, EN 10025-2:2019 — Hot rolled products of structural steels — Part 2: Technical delivery conditions for non-alloy structural steels. EN 10025-2 ↩

4. American Institute of Steel Construction, ANSI/AISC 360 — Specification for Structural Steel Buildings. AISC 360 ↩

5. European Committee for Standardization, EN 1993-1-1 (Eurocode 3) — Design of steel structures — Part 1-1: General rules and rules for buildings. Eurocode 3 ↩

6. Standardization Administration of China, GB/T 1591 — High strength low alloy structural steels. GB/T 1591 ↩ ↩²

7. European Committee for Standardization, EN 10204:2004 — Metallic products — Types of inspection documents. EN 10204 ↩ ↩²

Zitieren als Wayland Steel Editorial Team (2026). ASTM A36 vs S355 Steel — Cross-Standard Equivalents and Selection. Wayland Steel Insights. https://www.waylandsteel.com.cn/de-de/insights/astm-a36-vs-s355-cross-standard-equivalents/