Can A572 Gr.50 substitute for A709 Gr.50 on a bridge?

Chemically the plates are near-identical, but A709 adds mandatory CVN testing by temperature zone (and fracture-critical controls where specified). Substitution needs the bridge authority’s approval and the test evidence.

Grades · Structural & HSLA Steel · A709 Gr.50

A709 Gr.50

Data verified

ASTM A709 Grade 50 is the bridge version of A572 Gr.50: the same 50 ksi HSLA chemistry, but purchased to the bridge specification with Charpy toughness requirements tied to service-temperature zones, and fracture-critical options for tension members.

DINS355J2 (near)

AISIA709 Gr.50

JISSM520B (near)

CategoryStructural & HSLA Steel

Chemical composition

Element	Content (%)
C	≤0.23
Si	≤0.40
Mn	≤1.35
P	≤0.035
S	≤0.045
Note	CVN toughness mandatory for bridge (T/F) zones per A709

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Yield strength	≥345 MPa (50 ksi)
Tensile strength	≥450 MPa (65 ksi)
Impact	CVN per temperature zone (bridge requirement)
Density	7.85 g/cm³

Heat treatment

Supplied as-rolled or normalized; ordered to fracture-control requirements when used in tension or fracture-critical bridge members.

Equivalent grades

Standard	Designation
din	S355J2 (near)
aisi	A709 Gr.50
jis	SM520B (near)
gb	Q355B (near)

Compare side by side: A709 Gr.50 vs A572 Gr.50

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Highway and railway bridges, fracture-critical members, AASHTO-specified structures.

Processing: Use A709 (not plain A572-50) whenever the contract is a US bridge job — the toughness testing and reporting are part of the deliverable.

FAQ

Can A572 Gr.50 substitute for A709 Gr.50 on a bridge?: Chemically the plates are near-identical, but A709 adds mandatory CVN testing by temperature zone (and fracture-critical controls where specified). Substitution needs the bridge authority’s approval and the test evidence.

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Source: ASTM A709 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.