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
Export packing of ASTM A572 Grade 50 plate is by skid: up to 5 t per pack, steel straps, corner boards, stencilled heat numbers and a pack list that references the 3.1 certificates. Six-metre plate loads 24–25 t into a 40' HC. Long and heavy plate is shipped flat-rack or breakbulk via Derince. HS code 7208.51 / 7208.52.
| 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
Every lot of ASTM A572 Grade 50 plate carries an EN 10204 3.1 inspection certificate listing heat, chemistry, mechanical and impact results. On request we add 3.2 witnessing by a classification society or inspector, EN 10160 ultrasonic testing and supplementary impact tests at the customer's design temperature.
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.