When sourcing structural steel globally, S235JR (EN 10025-2) and ASTM A36 are two of the most common “mild structural steel” grades you’ll see on drawings and purchase orders. They are often treated as roughly comparable in trade—but they are not identical, and the safest approach is to match the required standard system (EN vs ASTM) and verify with the mill test certificate (MTC/MTR).

Below is a practical comparison you can use for quoting, substitution checks, and project communication.

1) Standards and Naming: EN vs ASTM

S235JR (EN 10025-2)

• S = structural steel

• 235 = minimum yield strength (MPa) for thinner products (varies with thickness)

• JR = Charpy impact toughness requirement: 27 J at +20°C (typical EN definition)

ASTM A36 (A36/A36M)

• “A36” is widely associated with 36 ksi minimum yield strength for common thickness ranges (again, thickness and product form matter).

2) Quick Comparison Table (Most Asked Differences)

Data basis for S235JR mechanical/impact/chemistry shown in EN 10025-2 aligned declarations/datasheets.
Data basis for A36 mechanical/chemistry and thickness notes shown in common A36 plate summaries.

3) Mechanical Properties: Yield/Tensile (and Why Thickness Matters)

S235JR mechanical properties (EN-style, thickness-dependent)

EN 10025-2 tables commonly specify that minimum yield strength decreases as thickness increases, while tensile bands may also shift by thickness group. For example, one EN-aligned DoP/table shows yield stepping from 235 MPa (≤16 mm) down to 185/175 MPa in higher thickness ranges, with tensile ranges such as 360–510, 350–500, 340–490 MPa depending on thickness.

A36 mechanical properties (common plate summary values)

A36 plate summaries commonly list:

• Tensile: 58–80 ksi

• Yield: 36 ksi min

• Note: Yield point is 32 ksi for plates over 8″ (thickness effect)

Practical takeaway:
If your project includes thick plate, “A36 vs S235JR” is not a single number comparison—thickness drives the guaranteed minimum yield for both standards.

4) Impact Toughness: The Biggest “Hidden” Difference

If your customer, engineer, or end-user is in an EN/CE mindset, toughness classes are a standard part of ordering:

• S235JR includes Charpy impact energy minimum 27 J at +20°C (JR).

For ASTM A36, toughness is not expressed as “JR/J0/J2” in the grade name. If impact toughness is required, it’s usually handled via supplementary requirements / separate specifications on the PO.

Practical takeaway:
If the application is sensitive (low temperature, dynamic loading, fracture-critical), don’t assume A36 “equals” S235JR just because yield is close—confirm the toughness/test requirement explicitly.

5) Chemical Composition (Typical Limits Shown in Common Datasheets)

S235JR (example EN-aligned limits)

A commonly referenced EN datasheet shows (heat/ladle analysis) limits by thickness such as:

• Carbon 0.17 max (≤40 mm), 0.20 max (>40 mm)

• Mn ≤1.40

• P ≤0.035, S ≤0.035

• N ≤0.012

• Cu ≤0.55

It also lists maximum carbon equivalent (CEV) limits by thickness (e.g., 0.35 / 0.38 / 0.40 bands).

A36 (plate summary limits by thickness)

One common A36 plate summary lists (by thickness band):

• Carbon max increases with thickness (e.g., 0.25% → 0.29%)

• Mn ranges such as 0.80–1.20% (varies by thickness band)

• P max 0.04%, S max 0.05%

• Si max commonly 0.40% (or a range depending on thickness)

• Cu 0.20% min when specified

Practical takeaway:
Both are “mild structural steels,” but EN documentation for S235JR often includes clear CEV controls and a named toughness class (JR), which is why EN buyers frequently prefer ordering by EN grade when compliance is European.

6) Are They Equivalent?

The honest answer: No official 1:1 equivalence exists.

However, many steel equivalency charts place A36 in the S235 family range (often listing S235 variants such as S235J2 and referencing S235JR nearby).

What you can say in a quote (safe wording)

• “S235JR and ASTM A36 are commonly treated as comparable for general structural use, but substitution must be approved by the project engineer and verified against required mechanical/toughness/testing requirements.”

7) Which One Should You Choose?

Choose S235JR when:

• The project is governed by EN/European specifications

• The buyer expects JR impact toughness to be inherently covered

• You need EN-style documentation of thickness-dependent properties

Choose A36 when:

• The project is governed by ASTM/AISC-style material callouts

• The buyer wants the common US structural grade with familiar ksi properties and A36 supply chain

8) How to Specify Correctly (Avoid Rework)

When requesting quotes (or approving substitutions), include:

1. Standard + grade (EN 10025-2 S235JR or ASTM A36/A36M)

2. Product form (plate, sheet, beam, angle, bar)

3. Thickness range (critical for yield guarantees)

4. Impact requirement (JR implied for S235JR; for A36 specify if needed)

5. Certificate requirement (MTC/MTR type, heat number traceability)

FAQs

Is S235JR stronger than A36?

Not strictly. A36 often quotes 250 MPa (36 ksi) minimum yield for common thicknesses, while S235JR is 235 MPa minimum yield at thinner thickness—but both change with thickness and specification details.

Why do engineers like S235JR in Europe?

Because the grade name embeds a toughness class (JR) and EN tables commonly show structured, thickness-based property requirements.

Can I substitute A36 for S235JR (or vice versa)?

Often it’s possible for general structures, but it should be treated as an engineering decision, not a “direct equivalent,” especially if toughness/testing is required. Equivalency charts can guide discussion but do not replace project approval.