What is ASTM A572 Grade 50 plate?
A572 is ASTM's high-strength low-alloy columbium-vanadium structural steel, in five grades named for yield in ksi: 42, 50, 55, 60 and 65. Grade 50 dominates — 345 MPa yield, 450 MPa tensile, elongation 18 % (200 mm) / 21 % (50 mm) — and is the default plate and shape material of AISC design (with A992 for wide-flange beams). The standard allows four alloying "types" (1: Nb, 2: V, 3: Nb + V, 5: Ti-V) and caps carbon at 0.23 %, manganese at 1.35 %; impact tests are not mandatory but are ordered as a supplementary requirement (typically 20 J at −20 °C or per AASHTO zones for A709). Grade 50 is available up to 100 mm; Grades 60 and 65 only to 32 mm. In practice A572-50 and S355J2 are cross-accepted in most non-code structural work, but the certificate must show the grade the drawing calls for — an ASTM-designed crane runway wants A572, a Eurocode one wants S355.
Chemical composition
| Element | C | Mn | P | S | Si | Nb | V |
|---|---|---|---|---|---|---|---|
| max. % (ladle) | ≤ 0.23 | ≤ 1.35 | ≤ 0.030 | ≤ 0.030 | ≤ 0.40 | 0.005–0.05 (Type 1/3) | 0.01–0.15 (Type 2/3) |
Type 3: Nb + V ≤ 0.15. CEV typically 0.38–0.43. Cu ≥ 0.20 on order for weathering.
Mechanical properties
| Grade | Yield min (MPa / ksi) | Tensile min (MPa / ksi) | Elongation min (200 / 50 mm) | Max thickness |
|---|---|---|---|---|
| Gr. 42 | 290 / 42 | 415 / 60 | 20 % / 24 % | 150 mm |
| Gr. 50 | 345 / 50 | 450 / 65 | 18 % / 21 % | 100 mm |
| Gr. 55 | 380 / 55 | 485 / 70 | 17 % / 20 % | 50 mm |
| Gr. 60 | 415 / 60 | 520 / 75 | 16 % / 18 % | 32 mm |
| Gr. 65 | 450 / 65 | 550 / 80 | 15 % / 17 % | 32 mm |
Equivalent grades
| System | Grade | Note |
|---|---|---|
| EN 10025-2 | S355JR / J0 / J2 | by impact class ordered |
| EN 10025-4 | S355M (TMCP) | |
| ASTM | A992 | shapes, 345–450 MPa yield window |
| ASTM | A709 Gr. 50 / 50W | bridge version with CVN zones |
| JIS G3106 | SM490A/B | |
| GB/T 1591 | Q355B |
Thickness range and stock sizes
| Thickness | Widths × lengths | Availability |
|---|---|---|
| 6–12 mm | 2 000 / 2 438 × 6 000–12 000 | to order 2–4 weeks |
| 15–40 mm | 2 000 / 2 438 / 2 500 × 6 000–12 000 | to order 2–4 weeks |
| 50–100 mm | 2 000–2 500 × 6 000 | to order 3–5 weeks |
Weight per m² and per plate
| Thickness | kg/m² | 1 500 × 6 000 (kg) | 2 000 × 6 000 (kg) | 2 500 × 12 000 (kg) |
|---|---|---|---|---|
| 6 mm | 47.1 | 424 | 565 | 1 413 |
| 8 mm | 62.8 | 565 | 754 | 1 884 |
| 10 mm | 78.5 | 707 | 942 | 2 355 |
| 12 mm | 94.2 | 848 | 1 130 | 2 826 |
| 15 mm | 117.8 | 1 060 | 1 413 | 3 533 |
| 20 mm | 157.0 | 1 413 | 1 884 | 4 710 |
| 25 mm | 196.3 | 1 766 | 2 355 | 5 888 |
| 30 mm | 235.5 | 2 120 | 2 826 | 7 065 |
| 40 mm | 314.0 | 2 826 | 3 768 | 9 420 |
| 50 mm | 392.5 | 3 533 | 4 710 | 11 775 |
| 60 mm | 471.0 | 4 239 | 5 652 | 14 130 |
| 80 mm | 628.0 | 5 652 | 7 536 | 18 840 |
| 100 mm | 785.0 | 7 065 | 9 420 | 23 550 |
Nominal weights — mill tolerance to EN 10029 class A adds up to +4 % on thin plate; invoiced on theoretical weight unless agreed otherwise.
Welding, cutting and forming
Prequalified under AWS D1.1 with E7018 / ER70S-6 / F7A2 consumables; preheat per D1.1 Table 3.3 (Category B): none up to 19 mm, 10 °C to 38 mm, 65 °C to 65 mm, 110 °C above. Low-hydrogen practice is standard. Cold forming 2 × t (1.5 × t for Type 1); flame cutting with edges ground on dynamic members; laser to 20 mm, plasma to 50 mm. Galvanising: silicon ≤ 0.04 % or 0.15–0.25 % avoids the Sandelin reactive range — specify when the plate will be hot-dip galvanised.
Where it is used
- AISC-designed buildings, mezzanines and pipe racks
- Crane runways and lifting equipment to ASME B30 / CMAA
- Oil & gas skids, module frames and structural steel in Gulf plants
- Bridges (as A709 Gr. 50) and transport structures
- Construction and mining equipment fabricated to ASTM
- Wind, solar and telecom structures to US specifications
A572 Grade 50 vs S355
Same strength class (345 vs 355 MPa yield) and similar chemistry; the differences are in the paperwork and the toughness default. S355J2 always carries 27 J at −20 °C; A572-50 has no impact test unless ordered. A572 caps carbon at 0.23 % and always micro-alloys with Nb or V; S355 may reach 0.24 % C without micro-alloying. In practice they substitute for each other when the designer accepts it — order A572 with CVN at −20 °C to match J2. See S355J2 and S355JR.
Price
A572 Gr. 50 is priced about 280 USD/t over the S235JR base as an ASTM-certified mill-order grade. The band below is the indicative FOB Istanbul range; Charpy testing and 3.2 inspection are extra.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
ASTM A572 Grade 50 plate is packed as follows: skids up to 5 t, strapped; heavy plate on bearers. Loading: 40' HC ≈ 24–25 t of 6 m plate; 12 m flat-rack. HS code is assigned by surface and alloy: 7208 (hot-rolled), 7209 (cold-rolled), 7210 (coated), 7225 / 7226 (alloy).
| Term | Detail |
|---|---|
| MOQ | 10 t of one thickness |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | To order 2–4 weeks (Turkish mill programme) |
| Packing | Skids up to 5 t, strapped; heavy plate on bearers |
| Container / truck | 40' HC ≈ 24–25 t of 6 m plate; 12 m flat-rack |
| Documents | Invoice, packing list, EN 10204 3.1 (3.2 on request), certificate of origin; SASO / SONCAP / PVoC on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight for orders above 100 t |
Certificates and testing
The paperwork travelling with ASTM A572 Grade 50 plate is an EN 10204 3.1 certificate covering chemistry, mechanical values and the delivery condition. A 3.2 certificate with an inspector attending at the mill is arranged when the project file demands it. Ultrasonic examination to EN 10160 and additional low-temperature impact tests are quoted together with the plate.
How to order
Specify grade, type (if any), thickness × width × length, tonnage, Charpy requirement and certificate (MTR per ASTM A6 / EN 10204 3.1); imperial widths (96 in = 2 438 mm) are available.
Standards
- ASTM A572/A572M — Grades 42, 50, 55, 60, 65
- ASTM A6 general requirements
- AWS D1.1 prequalified base metal
- ASTM A709 Gr. 50 (bridge version) on request
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: A572 Gr 50 · S355J2 · S355JR
Frequently asked questions
What is ASTM A572 Grade 50?
A high-strength low-alloy (HSLA) structural steel plate with 345 MPa (50 ksi) minimum yield and 450 MPa (65 ksi) minimum tensile, micro-alloyed with niobium and/or vanadium, used for AISC-designed structures and equipment.
Is A572 Grade 50 equivalent to S355?
They are the standard cross-equivalents: 345 vs 355 MPa yield, similar chemistry. S355J2 includes −20 °C impact testing by default; A572-50 needs it ordered as a supplement.
What is the difference between A572 Grade 50 and A36?
A36 is a plain carbon steel with 250 MPa yield; A572-50 is micro-alloyed with 345 MPa yield — 38 % stronger — at only a few percent more cost, which is why Grade 50 has replaced A36 in most structural work.
Can A572 Grade 50 be galvanised?
Yes — specify silicon ≤ 0.04 % or 0.15–0.25 % at the mill to avoid the reactive range that causes thick, dull zinc coatings.
What thickness is A572 Grade 50 available in?
Up to 100 mm (4 in) by the standard; we roll 6–100 mm to order. Grades 60 and 65 are limited to 32 mm.