What is ASTM A36?
ASTM A36 is the predominant general structural steel covered by ASTM standards in the United States. The designation "36" refers to its minimum yield strength of 36 ksi (approximately 250 MPa). It covers nearly all structural forms, including steel plates, structural sections, round bars and flat bars.
It is widely adopted for projects complying with AISC standards throughout North America. No mandatory impact test is specified in the standard specification.
Typical Applications:
This plate grade is primarily used for structural frames of North American factories, highway bridge components, heavy equipment bases, storage racking, transport trailers, mechanical support frames, secondary marine structures, guardrails and general carbon steel fabrication.
What is S235JR?
S235JR is a core structural steel specified under European standard EN 10025-2.
S = Structural steel
235 = Minimum yield strength of 235 MPa
JR = Charpy V-notch impact test requirement at 20°C with a minimum energy of 27 J
Its low carbon content delivers excellent weldability. CE marking is mandatory for market access within the European Union.
Typical Applications:
This grade is extensively applied to EU industrial plant construction, European construction machinery frames, container components, auxiliary wind turbine supports, steel platform structures, railway carriages, pipe supports, building scaffolding, and all structural fabricated goods bearing the CE marking.
What is Q235B?
Q235B is the most commonly used low-carbon structural steel in China, specified in GB/T 700.
Q = Yield strength
235 = Minimum yield strength of 235 MPa
B = Charpy impact test requirement at 20°C
It features large domestic output, stable supply and competitive pricing. Widely used in building steel structures, mechanical supports, racking and infrastructure works, it is a frequently selected material for Chinese export products.
Typical Applications:
This grade is widely utilized for domestic industrial buildings, warehouse steel structures, logistics racking, light machinery casings, road guardrails, welded pipes, tower supports, prefabricated steel structures, general supports, and Belt and Road Initiative infrastructure projects.
What is SS400?
SS400 complies with Japanese standard JIS G3101. SS stands for structural steel; 400 indicates a minimum tensile strength of 400 MPa.
No strict limitation is imposed on manganese content. It is widely used for plant construction and machinery frames in Japan, Vietnam, Thailand and other Southeast Asian markets. No mandatory impact test is required by the standard.
Typical Applications:
This grade is extensively adopted for Japanese factory construction, Southeast Asian industrial workshops, automotive secondary components, agricultural machinery frames, simple port support structures, solar mounting brackets, steel formwork and equipment frames for Japanese-brand machinery.
What is St37-2?
St37-2 comes from the obsolete German standard DIN 17100 and has been officially superseded by S235JR.
It now only appears on legacy equipment drawings and renovation projects. St37-2 is no longer specified for new-build projects across Europe.
Typical Applications:
This grade is used for maintenance and spare parts of vintage German mechanical equipment, retrofits of old European factories built in the last century, and component replacement for traditional production lines. It is not recommended for new construction projects.
What is A283 Grade C?
A283 Grade C is an ASTM steel grade applicable exclusively to steel plates. It cannot be used for H-beams, angles or other structural sections.
Its yield strength is lower than that of A36. It is mainly used for general storage tanks, secondary platework and non-critical welded plate structures in North America.
Typical Applications:
This grade is primarily used for low-pressure atmospheric storage tanks, non-load-bearing casing plates, equipment housing panels, simple welded silos, duct plates, base plates for light machinery and non-dynamic plate structures in North America.
A36 S235JR Q235B SS400 ST37 A283 Grade C Carbon Steel Plate Specification
| Item | Description |
|---|---|
| Product | Carbon Steel Plate / Structural Steel Plate |
| Steel Grades | ASTM A36, S235JR, Q235B, SS400, ST37, ASTM A283 Grade C |
| Standards | ASTM A36/A36M, EN 10025-2, GB/T 700, JIS G3101, DIN 17100, ASTM A283/A283M |
| Thickness | 3–300 mm |
| Width | 1,000–4,000 mm |
| Length | 2,000–18,000 mm |
| Manufacturing Process | Hot Rolled |
| Delivery Condition | As Rolled, Normalized Rolling, or Normalized (depending on grade) |
| Surface Finish | Mill Finish, Shot Blasted, Painted (Optional) |
| Cutting Service | Flame Cutting, Laser Cutting, Plasma Cutting, Water Jet Cutting |
| Inspection | Chemical Analysis, Tensile Test, Yield Strength Test, Dimension Inspection, Ultrasonic Testing (Optional) |
| Certification | EN 10204 3.1 / 3.2, Mill Test Certificate (MTC) |
| Applications | Steel Structures, Bridges, Machinery, Storage Tanks, Construction Equipment, General Fabrication |
A36 vs S235JR vs Q235B vs SS400 vs ST37 vs A283 Grade C: Chemical Composition
| Grade | C | Mn | Si | P | S |
|---|---|---|---|---|---|
| A36 | 0.26 | 1.20 | - | 0.040 | 0.050 |
| S235JR | 0.17 | 1.40 | - | 0.035 | 0.035 |
| Q235B | 0.20 | 1.40 | 0.35 | 0.045 | 0.045 |
| SS400 | 0.20 | No limit | - | 0.050 | 0.050 |
| St37-2 | 0.21 | - | - | 0.050 | 0.050 |
| A283 Gr.C | 0.24 | 0.90 | 0.40 | 0.040 | 0.050 |
A36 vs S235JR vs Q235B vs SS400 vs ST37 vs A283 Grade C: Mechanical Property
| Grade | Min Yield Strength (MPa) | Tensile Strength (MPa) | Min Elongation | Standard Impact @20℃ |
|---|---|---|---|---|
| A36 | 250 | 400–550 | 20% | Not required |
| S235JR | 235 | 360–510 | 26% | 27J |
| Q235B | 235 | 370–500 | 26% | 27J |
| SS400 | 245 | 400–510 | 21% | Not required |
| St37-2 | 235 | 360–480 | 25% | 27J |
| A283 Gr.C | 205 | 380–515 | 25% | Not required |
A36 vs S235JR vs Q235B vs SS400 vs ST37 vs A283 Grade C: Welding Performance Comparison
| Grade | Carbon Equivalent Level | Welding Suggestion | Restriction Reminder |
|---|---|---|---|
| A36 | Medium | Thin plates free welding; preheat ≥75℃ for thickness >25mm | Higher max carbon risk of hardening |
| S235JR | Low | Preheating generally unnecessary | Best weldability among all grades |
| Q235B | Low-medium | Normal welding process for most thickness | Widely verified by domestic fabricators |
| SS400 | Variable | Preheat recommended for thick plate | Unrestricted Mn leads to inconsistent batches |
| St37-2 | Medium | Same process as S235JR | Higher impurity limit, avoid critical welding joints |
| A283 Gr.C | Medium | Suitable for simple plate welding | Not recommended for dynamically loaded structures |
Procurement & Material Selection Guidelines
Export to the European Union (CE marking required)
Select S235JR. Do not substitute with A36 or Q235B without third-party certification. St37-2 may only be used for equipment overhaul. Consistent impact properties and strict chemical composition control ensure compliance for CE assessment.
Projects complying with US AISC / ASTM Standards
Preferred grade: ASTM A36. Where flat plates are solely required for non-critical storage tanks, select A283 Grade C. Confirm if ultrasonic testing (UT) is required prior to ordering.
Domestic Chinese Projects and Low-Cost Bulk Orders
Select Q235B. It features stable supply, short lead times and competitive pricing, delivering consistent quality for mass production of general steel structures.
Export to Japan, Thailand, Vietnam and other Southeast Asian Markets
Follow drawing specifications: Where SS400 is specified, SS400 shall take priority. Q235B may be considered for non-critical components. Take note of variations in mechanical properties between production batches.
Maintenance & Retrofit of Legacy German Equipment
S235JR may be used as a replacement for St37-2 as shown on original drawings. S235JR benefits from improved modern quality control practices compared to the obsolete St37-2.
Low-Temperature Service Conditions (<0°C)
Prioritize grades with mandatory standard impact testing: S235JR / Q235B. Avoid grades such as A36, SS400 and A283 Grade C unless customized impact testing is ordered.
Key Procurement Reminder: Always request the Mill Test Certificate (MTC) prior to shipment. Data shown on the MTC must correspond to the ordered steel grade. GNEE can provide sampling test reports based on actual production batches.
Click to obtain the MTC for the relevant grade
Why Choose GNEE Steel?
GNEE Steel is a professional supplier of carbon structural steel plates and section steel with ISO, CE and ASME certification. We fully support global buyers sourcing these six mild steel grades:
Complete product portfolio: Hot rolled plate, flat bar, H-beam, angle steel, channel steel for A36, S235JR, Q235B, SS400; A283 Grade C steel plate supply.
Standardized documents: Official MTC test reports, commercial invoice, packing list, certificate of origin to meet customs clearance worldwide. All MTC contain real factory test data.
FAQ
Can A36 directly replace S235JR?
ASTM A36 can directly replace S235JR for most general structural uses, but it is not an exact 1:1 match. They share close yield and tensile properties, though ASTM A36 has slightly higher strength thresholds and different mandatory testing rules.
Is Q235B fully equivalent to S235JR?
No, Q235B is not fully equivalent to S235JR. While they are treated as close commercial matches with similar yield strengths, they belong to different regional standards-Chinese and European-and have subtle differences in chemical limits and testing rules.
Can Q235B be used for North American A36-design projects?
Yes, Q235B can often be used for non-critical North American A36-design projects, but they have slightly different mechanical properties and are governed by separate standards.
