Gr.55 raises yield from 345 to 380 MPa and tensile from 450 to 485 MPa at the same 0.25% carbon cap. It saves some weight over Gr.50 but is stocked far less widely, so mills often offer Gr.50 or Gr.65 from stock instead.

Grades · Structural & HSLA Steel · A572 Gr.55

A572 Gr.55

Data verified

ASTM A572 Grade 55 is a columbium-vanadium HSLA structural steel one step above the ubiquitous Gr.50: yield rises to ≥380 MPa (55 ksi) and tensile to ≥485 MPa (70 ksi) while chemistry stays lean and weldable. It is used where Gr.50 sections become too heavy but Gr.65 hardenability is not wanted.

DINS355J2 (near)

AISIA572 Gr.55

JISSM490B (near)

CategoryStructural & HSLA Steel

Chemical composition

Element	Content (%)
C	≤0.25
Si	≤0.40
Mn	≤1.35
P	≤0.04
S	≤0.05
Note	Strength comes from a Nb, V or Nb-V addition — Type 1, 2, 3 or 5 must be specified on the order

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

Properties

Yield strength	≥380 MPa
Tensile strength	≥485 MPa
Density	7.85 g/cm³

Heat treatment

Supplied as-rolled (hot-rolled HSLA); not normally heat treated. Normalizing only if specified on the order.

Equivalent grades

Standard	Designation
din	S355J2 (near)
aisi	A572 Gr.55
jis	SM490B (near)
gb	Q355B (near)

Compare side by side: A572 Gr.55 vs A572 Gr.50 · A572 Gr.55 vs A572 Gr.60

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

Applications & Processing

Applications: Bridges, building frames, transmission towers, crane booms, heavy equipment frames.

Processing: Good weldability for an HSLA grade; control heat input and use low-hydrogen practice on thick, restrained joints. Cold forming radii are larger than for Gr.50.

FAQ

A572 Gr.55 vs Gr.50?: Gr.55 raises yield from 345 to 380 MPa and tensile from 450 to 485 MPa at the same 0.25% carbon cap. It saves some weight over Gr.50 but is stocked far less widely, so mills often offer Gr.50 or Gr.65 from stock instead.

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Source: ASTM A572 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.