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ASME SA572/SA572M Grade 50 is the ASME Boiler and Pressure Vessel Code version of ASTM A572 Grade 50 — the high-strength low-alloy (HSLA) columbium-vanadium structural steel that carries bridges, building frames, transmission towers and heavy equipment. The two designations describe the same steel: the ASME text for SA-572/SA-572M states on its face that it is identical with ASTM Specification A572/A572M-21ε1. Chemistry, mechanical requirements and metallurgy are the same. What changes is the endorsement. An SA prefix means the specification has been adopted into ASME BPVC Section II, Part A, so the material is produced, tested and documented under an ASME-compliant quality system and is a code material.
Grade 50 is the workhorse level of the A572 family. Its strength does not come from carbon — at 0.23 % maximum, Grade 50 is leaner in carbon than plain structural carbon steel — but from small additions of columbium (niobium) and vanadium, which refine the grain and precipitate-strengthen the ferrite. That is why the grade reaches 345 MPa minimum yield while staying weldable and formable. BBN supplies SA572 Gr.50 hot rolled sheet and plate cut to size, tested per heat and certified on the mill test certificate with the ASME designation and code edition stated.
345 MPaMin. Yield Strength50 ksi — the "50" in the grade name
450 MPaMin. Tensile Strength Rm65 ksi, a minimum not a band
18 %Min. Elongation, 200 mm gauge21 % on the 50 mm gauge
0.23 %Max. CarbonNb 0.005–0.05 / V 0.01–0.15
How to read this page: every value below is an ASME SA572/SA572M requirement — a minimum or a specified limit, not a typical mill result. The grade sets yield, tensile and elongation, and deliberately leaves toughness, heat treatment, ultrasonic acceptance and through-thickness properties to the purchaser as supplementary order items. What is actually delivered is what appears on the MTC of the heat you buy, so quote thickness, product form, delivery condition, the ASME code edition you need on the certificate and any extra testing together in the enquiry.
02Technical Specifications
Supply programme published for ASME SA572/SA572M SA572 Grade 50 on this product page.
Item
Specification
Executive Standard
ASME SA572/SA572M — adopted into ASME BPVC Section II, Part A; identical to ASTM A572/A572M-21ε1
Steel Grade
SA572 Grade 50 (SA572 Gr.50) written SA572M Grade 345 in the metric edition — same material, two unit systems
Steel PlateSheetBarShapeshot rolled sheet and plate on this page
Thickness Range
4 – 400 mm
Width Range
1 000 – 4 000 mm
Length Range
4 000 – 12 000 mm
Production Way
Hot rolled — the usual supply route for this grade
Delivery Condition
Hot rolled / as rolled (usual supply) — see section 07 for what the order can add
Impact Requirement
None in the base specification — Charpy is a supplementary order item, see section 06
MOQ
1 PCsingle plate or cut length accepted
Supply Ability
10 000 MT per month
Lead Time by Quantity
1 – 10 t: 5 days · 10 – 50 t: 10 days · > 50 t: negotiable
Delivery Time
Confirmed against the rolling programme and the quantity schedule — not published as a fixed number of days
Loading Port
Confirmed per order — not published on this product sheet
Packaging
Standard export seaworthy packing, or as required
Certification
Mill Test Certificate stating the ASME designation and edition; EN 10204 3.1 / 3.2 and third-party inspection on request
Payment Terms
L/CT/TD/PWestern UnionPaypalMoney Gram
Processing Services
Cutting to length and width, profiling, bevelling, bending, drilling, welding, shot blasting and painting
Three things worth knowing about this table. First, the 4 – 400 mm thickness, 1 000 – 4 000 mm width and 4 000 – 12 000 mm length figures are the production range published for this product — not every thickness can be rolled in every width and length combination, so send the actual size. Second, the ASME endorsement is not automatic: if the material is going into code work, write "ASME SA572/SA572M" plus the code edition into the purchase order so the MTC carries it. Third, dimensional tolerances follow the general requirements specification (A6/A6M) and the agreed order, not the grade text. Loading port and stock lead time are not published on this sheet and are confirmed per order.
03Grade Designation
What each part of the name SA572/SA572M Grade 50 tells a buyer.
Element
Meaning
S
The ASME prefix. A material published with an SA designation has been adopted into the ASME Boiler and Pressure Vessel Code, Section II, Part A. It is the same specification text as the ASTM one, plus the code endorsement and the quality-system obligations that come with it.
A572
The ASTM designation. Unlike A36, where the number is a strength value, A572 is a serial number — it carries no strength meaning at all. The strength lives entirely in the grade that follows it.
M
Metric (SI) edition. SA572 and SA572M are the same material quoted in two unit systems: Grade 50 (ksi) = Grade 345 (MPa). Order either one, but do not treat them as two grades.
Grade 50
The specified minimum yield strength in ksi — 50 ksi = 345 MPa — which is the whole reason the level is called "50". Tensile and elongation come with it, toughness does not.
Type
The alloy-type suffix that says which micro-alloy route delivers the strength. See the alloy-type table below — and read the note under it, because two different Type numbering systems are in circulation.
The five strength levels of A572/A572M — Grade 50 is the default.
Two cautions on the ladder above. Grades 60 and 65 are not intended for welded bridge applications — the specification says so in its scope — so a welded bridge girder is normally specified as Grade 50 or as A709 Grade 50. And these are the minimum values of the governing edition: yield falls away on thicker sections in some editions, so a design value has to be re-checked against the edition and the thickness bracket the project cites rather than taken off a summary table.
Alloy types — where the strength actually comes from.
Type
Alloy element
Heat analysis, %
Type 1
Columbium (niobium), Nb
0.005 – 0.05
Type 2
Vanadium, V
0.01 – 0.15
Type 3
Columbium + vanadium
Nb 0.005 – 0.05, V 0.01 – 0.15, Nb+V 0.02 – 0.15
Type 5
Titanium + nitrogen, with vanadium
Ti 0.006 – 0.04, N 0.003 – 0.015, V 0.06 max
Two different Type numbering systems are in circulation — do not let them collide on a purchase order. In the ASTM A572 text itself, Type is an alloy route: Type 1 is niobium, Type 2 is vanadium, Type 3 is both, Type 5 is titanium-nitrogen. In bridge and building practice, however, A572 Gr.50 "Type 1 / Type 2" is often used to mean a notch-toughness class — Type 2 meaning Charpy V-notch testing is required. Those are unrelated classifications. When you order, state which system you mean, name the alloy type you want, and add Charpy separately with its temperature and absorbed energy. Otherwise the mill will default to a non-tested, non-characterised supply.
ASTM A572 and ASME SA572 side by side.
Item
ASTM A572 / A572M
ASME SA572 / SA572M (this page)
Issued by
ASTM International
ASME, as a code material in BPVC Section II, Part A
Chemistry & mechanicals
Baseline requirements
Identical — the ASME text states it is identical with ASTM A572/A572M-21ε1
Typical use
General structural work: bridges, buildings, towers, machinery and equipment frames
The same structural work, plus code-fabricated boiler, pressure vessel and nuclear components and their non-pressure structural attachments
Documentation
MTC certified against the ASTM text
MTC carrying the ASME designation and code edition, produced under an ASME-compliant quality system with the traceability that implies
Can one replace the other?
A572 cannot automatically stand in for SA572 on code work — an ASME-stamped manufacturer has to buy and certify the material as an SA material
SA572 can always be supplied where A572 is asked for; it is the same steel with extra assurance behind it
04Equivalent Grades
Common cross-standard references — a similar yield figure is not a licence to substitute.
The closest European match on yield. Impact classification is different — JR is a 20 °C class, while A572 Gr.50 carries no mandatory impact requirement at all.
EN 10025-2
S355J0 / S355J2
355 MPa
Use these when low-temperature toughness is needed, because plain A572 Gr.50 gives you none unless you order it.
The bridge-purpose version of A572 — same strength level, but it adds mandatory Charpy requirements. This is what a bridge project should normally call out.
Not an equivalent — it is a weathering steel. Only relevant when bare, unpainted atmospheric corrosion resistance is the requirement.
Strength proximity is not interchangeability. Chemistry limits, toughness requirements, thickness brackets and delivery conditions all differ between these standards, and a substitution has to be signed off by the designer against the governing code. Two traps are worth naming: JIS SM490A / SM490YA specify 325 MPa minimum yield, 20 MPa below A572-50, so "490 versus 572" is not the comparison it looks like; and A572 is not a weathering steel — the specification gives no atmospheric corrosion guarantee, and its Nb/V alloying improves strength and toughness, not corrosion resistance. Where bare outdoor exposure is the design condition, specify A588 or A709-50W instead.
05Chemical Composition
Heat analysis limits for SA572 Grade 50. The two rows the product sheet does not list are the ones that define the grade.
Element
Limit
Source
Carbon, C
0.23 % max
Product data sheet — same value in ASTM A572 Table 2
Manganese, Mn
1.35 % max
Product data sheet
Phosphorus, P
0.04 % max
Product data sheet
Sulfur, S
0.05 % max
Product data sheet
Silicon, Si
0.40 % max
Product data sheet — other editions publish 0.15 – 0.40 as a range
Columbium (niobium), Nb
0.005 – 0.05 %
ASTM A572 alloy type 1— not listed on the product data sheet
Vanadium, V
0.01 – 0.15 %
ASTM A572 alloy type 2— not listed on the product data sheet
Nb + V combined
0.02 – 0.15 %
ASTM A572 alloy type 3— not listed on the product data sheet
Copper, Cu
—
Not an A572 requirement— see the note below
Four things to keep straight when you read a certificate against this table. First, the product data sheet lists only C, Mn, P, S and Si — it omits Nb and V, which are exactly the elements the specification is named after ("columbium-vanadium structural steel") and the reason the grade reaches 345 MPa without extra carbon. Those two rows above come from the ASTM A572 alloy-type clause and will appear on the MTC. Second, silicon is published two ways: 0.40 % max here and in most commercial tables, and 0.15 – 0.40 % as a range in other editions. Third, P and S limits vary by edition and product form — 0.04 / 0.05 on this sheet, but 0.035 / 0.040 and 0.030 / 0.030 both circulate — so check the edition named on your order. Fourth, copper is not an A572 requirement: the "Cu ≥ 0.20 %" line that appears in some commercial tables belongs to weathering-steel specifications such as A588, not to A572. A572 sets no copper minimum and no corrosion guarantee.
06Mechanical Properties
Minimum requirements in SI units, as published for SA572 Grade 50.
Property
Requirement
Gauge / condition
Yield strength, ReH
345 MPa min50 ksi
Minimum, not a band
Tensile strength, Rm
450 MPa min65 ksi
Minimum, not a band
Elongation
18 % min
200 mm (8 in.) gauge length
Elongation
21 % min
50 mm (2 in.) gauge length
Impact test
—
Not a specification requirement; supplementary only
The same requirements in the ksi units the grade name comes from.
Property
Requirement
Tensile strength
65 ksi / 450 MPa
Yield strength
50 ksi / 345 MPa
Elongation
18 %
Impact test (if any)
—
Four cautions on the numbers above. First, 450 MPa is a minimum, not the top of a band — some commercial pages publish "450 – 655 MPa", which reads an upper limit into a specification that only sets a floor. Second, elongation is published as 18 % on the 200 mm gauge and 21 % on the 50 mm gauge; a few sources list "21 % / 23 %", which attaches the wrong figures to the wrong gauges. Third, impact testing is not a base requirement — the data sheet leaves the cell empty and marks it "if any". If your service temperature or code case needs Charpy V-notch, order it as a supplementary requirement and state both the test temperature and the minimum absorbed energy, because neither is implied by the grade name. Fourth, yield falls away on heavier sections in some editions, so confirm the thickness bracket with the mill before you use 345 MPa as a design input.
A572 does not lock the material to a delivery condition — the order does.
Item
Options
Delivery Condition
AR — As hot rolled (usual)N — NormalizedQuenchedTemperedTMCP
Additional Conditions
UTCharpy V-notchHICZ15 / Z25 / Z35Third-party test (SGS)Coated or shot blasted and painting
Surface Treatment
As rolledShot blastedPrimedPainted
What the specification sets, and what has to be added by the order.
Item
Status in SA572/SA572M
How it is obtained
Delivery condition
Not specified
As rolled is the usual route and keeps cost down; normalizing can be agreed, mainly for thick plate.
Heat treatment
Not specified
The grade reaches its strength through Nb/V micro-alloying and controlled rolling, not through heat treatment. Quenching and tempering is not an A572 route — quenched and tempered high-strength plate is specified under A514 / A517.
Impact toughness
Not specified
Order as a supplementary requirement, naming temperature and minimum absorbed energy.
Ultrasonic testing
Not specified
ASTM A578 / A578M at an agreed acceptance level, by agreement.
Through-thickness (Z) properties
Not specified
Z15 / Z25 / Z35 by agreement where the joint pulls through the plate thickness.
Third-party inspection
Not specified
SGS, BV, TUV or Intertek at the mill before shipment.
Certificate
MTC per the specification
EN 10204 3.1 as standard, 3.2 with third-party endorsement on request.
Read the data sheet line carefully. It lists Normalized, Quenched, Tempered, HIC, Impact Test and then adds the qualifier "Optional if not provided in rules" — and that qualifier is the important part: none of these are A572 requirements, they are order options. Two of them deserve a specific warning. Quenching and tempering is not a route this grade takes; a Q+T plate is a different product family (A514 / A517) and asking for it on A572 buys nothing but cost. HIC (hydrogen-induced cracking resistance) comes from pressure vessel and pipeline service conditions, and a structural steel project normally has no use for it. The normal supply is hot rolled, tested per heat and certified — anything beyond that has to be written into the order before rolling, not added afterwards.
08Typical Applications
Where SA572 Grade 50 plate, sheet, bar and shapes are normally consumed.
Bridge Girders & Structural Plates
Plate girders, cross-frames, gussets, splice and connection plates on riveted, bolted or welded structures — the use the grade was written for, and the reason it is stocked more widely than any other A572 level.
Building Frames & High-Rise Structures
Columns, beams, bracing and moment-frame members in multi-storey commercial and industrial buildings, where 345 MPa yield cuts section size and weight against plain carbon steel.
Transmission & Telecommunication Towers
Lattice towers, substation structures, lighting and communication poles — applications where strength-to-weight and fatigue resistance matter more than corrosion resistance.
Construction & Mining Equipment
Excavator booms, mining truck bodies, crane jibs and outrigger pads, bulldozer and rig frames — impact-tolerant, weldable plate that takes repeated loading.
ASME Code Pressure Parts
Non-pressure and structural parts of ASME-stamped boilers, pressure vessels and nuclear components — saddles, skirts, supports and attachments where the design calls for an SA-listed material.
Why this grade is chosen when the design needs more than plain carbon steel: it gives roughly 95 MPa more yield than A36 for a modest price step, it does it with micro-alloying rather than carbon so it still welds with ordinary consumables, and it is stocked in plate, sheet, bar and shapes in the same supply chain. What it does not give you is atmospheric corrosion resistance or guaranteed low-temperature toughness — those are different specifications and different orders.
09Processing, Testing & Supply
From mill plate to a certified, fabrication-ready item.
1
Cutting & Profiling
Plate and sheet cut to length and width, profiled to drawing and bevelled for weld preparation on flame, plasma or laser equipment.
2
Forming, Bending & Welding
Bending and rolling to radius, cold forming to the radius the thickness allows, plus welded assemblies built under a qualified procedure — preheat is generally not required up to about 25 mm, and thicker or highly restrained joints call for 100 – 150 °C with low-hydrogen consumables.
3
Surface Treatment
Shot blasting to remove mill scale, then shop primer or full paint system, followed by export marking and seaworthy packing.
4
Inspection & Certified Delivery
Chemical analysis and tensile testing per heat, Charpy, UT and Z-direction testing when specified, then the MTC carrying the ASME designation and code edition plus any third-party report.
Mill Test Certificate to EN 10204 3.1, or 3.2 with third-party endorsement
MTC stating the ASME SA572/SA572M designation and the BPVC code edition
Heat analysis and mechanical test report (yield, tensile, elongation, Charpy where ordered)
Nb / V alloy content recorded against the alloy type ordered
Ultrasonic testing report to the agreed acceptance level
Heat treatment chart where normalizing is ordered
Third-party inspection by SGS, BV, Intertek or another nominated agency
Export packing, marking and loading supervision
Quote checklist — you get a faster, comparable price if you send: thickness × width × length, quantity, product form (plate, sheet, bar or shape), delivery condition, the alloy type if you have a preference, whether the material is for ASME code work and which edition the certificate must show, required mechanical values plus impact temperature and energy if Charpy is needed, UT acceptance level and any Z-direction requirement, surface treatment, MTC type, destination port and payment terms. MOQ is 1 PC.
No. The chemistry, the mechanical requirements and the metallurgy are the same; the specification text is the same — the ASME edition says in its own heading that it is identical with ASTM A572/A572M-21ε1. The difference is administrative: SA means the specification has been adopted into the ASME Boiler and Pressure Vessel Code, Section II, Part A, so the material is produced, tested and documented under an ASME-compliant quality system. SA572 can always be supplied where A572 is asked for. The reverse is not true — for code work you must order SA572, because a certificate that only says "A572" will not carry the endorsement an inspector looks for.
Q2What is a "Type" on A572 Grade 50 — Type 1, Type 2 or Type 3?
In the ASTM A572 text, the Type is an alloy route: Type 1 is niobium (0.005 – 0.05 %), Type 2 is vanadium (0.01 – 0.15 %), Type 3 is both, Type 5 is titanium-nitrogen. Be aware that bridge and building practice uses a different Type numbering, where A572 Gr.50 Type 2 means "Charpy testing required". Those two systems have nothing to do with each other, so an order that just says "Type 2" is ambiguous. Name the alloy type you want and specify Charpy separately with its temperature and absorbed energy.
Q3Is A572 a weathering steel? Can I leave it unpainted?
No. A572 is a high-strength low-alloy steel, not a weathering steel: the specification gives no atmospheric corrosion guarantee, and the Nb/V alloying is there for strength and toughness, not for patina formation. Some commercial pages list a "Cu ≥ 0.20 %" line for A572 — that requirement belongs to weathering specifications such as A588. If bare, unpainted outdoor exposure is the design condition, specify A588 or A709-50W instead, and expect to paint or coat A572 for that service.
Q4Is the elongation 18 % or 21 %?
Both, on different gauge lengths: 18 % minimum on a 200 mm (8 in.) gauge and 21 % minimum on a 50 mm (2 in.) gauge. A few sources publish "21 % / 23 %", which attaches the wrong figures to the gauges — the specification values are 18 and 21. Always read the gauge length off the certificate line and match it to the gauge your calculation assumes.
Q5Can I substitute S355JR or Q345B for A572 Grade 50?
Only with the designer’s sign-off against the governing code. Similar yield is not interchangeability: chemistry limits, toughness classes, thickness brackets and delivery conditions all differ. Note in particular that the frequently cited JIS alternatives are weaker, not equivalent — SM490YA and SM490A specify 325 MPa minimum yield, 20 MPa below A572-50, because the JIS "490" is a tensile value while the A572 "50" is a yield value. S355JR is the closest European match at 355 MPa, but its JR impact class is a different concept from A572’s absence of any impact requirement.
Q6Should I move up to Grade 60 or 65 for a welded bridge?
Usually no — and in welded bridge work the specification actively discourages it: Grades 60 and 65 are not intended for welded bridge applications. A welded bridge girder is normally detailed in Grade 50 or in A709 Grade 50, which is the bridge-purpose version of the same strength level and carries mandatory Charpy requirements that plain A572 does not. Step up to Grade 60 only where the section actually uses the extra 70 MPa of yield and the welding procedure can carry it.
Get Your ASME SA572/SA572M Grade 50 Steel Quotation Now
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