- Description
Corten steel (weathering steel) refers to a group of low-alloy structural steels designed to form a stable, protective rust layer (patina) when exposed to outdoor environments. Different countries and standards use different grade systems, but they all belong to the same “weathering steel” family.
1. ASTM / AISI Corten Steel Grades (USA Standard)
These are the most widely used international weathering steel grades:
| Grade | Type | Key Features |
|---|---|---|
| ASTM A242 | Corten A equivalent | Early weathering steel grade, good atmospheric corrosion resistance |
| ASTM A588 | Corten B equivalent | Higher strength structural weathering steel |
| ASTM A606 | Sheet/strip weathering steel | Used for thin plates and decorative panels |
| ASTM A709 (Grade 50W / 50CR) | Bridge steel | Widely used in bridge construction |
👉 These grades are commonly referred to as Corten A and Corten B series materials in the market.
2. EN Standard Weathering Steel Grades (Europe)
European weathering steels are defined under EN 10025-5:
| Grade | Description | Application |
|---|---|---|
| S235J0W | Basic weathering structural steel | Light structural use |
| S355J0W | Most common grade | Bridges, buildings, outdoor structures |
| S355J2W | Improved low-temperature toughness | Heavy structural engineering |
| S355K2W | Higher impact toughness | Critical structural applications |
👉 “S355J0W” is one of the most widely used Corten-type steels in Europe.
3. Chinese Weathering Steel Grades (GB Standard)
China also has equivalent weathering steel grades:
| Grade | Equivalent Use |
|---|---|
| Q235NH | Basic weathering steel |
| Q295NH | Medium strength weathering steel |
| Q355NH | Main structural weathering steel |
| Q460NH | High-strength weathering steel |
4. Key Alloy System Behind All Corten Grades
Although grade names differ, all Corten steels share similar alloy design:
| Element | Function |
|---|---|
| Copper (Cu) | Improves rust layer stability |
| Chromium (Cr) | Enhances corrosion resistance |
| Nickel (Ni) | Improves toughness and patina formation |
| Phosphorus (P) | Promotes protective rust layer |
👉 This alloy system is what enables the self-protecting rust (patina) behavior.
5. Main Characteristics of Corten Steel Grades
Regardless of grade system, all Corten steels share:
- High atmospheric corrosion resistance
- Formation of stable red-brown rust layer
- No need for painting in many outdoor applications
- Long service life in outdoor environments
- Good structural strength (grade dependent)
6. Common Applications by Grade Type
Structural Grades (A242 / S355J0W / Q355NH)
- Bridges
- Buildings
- Outdoor frameworks
- Infrastructure projects
Heavy Duty Grades (A588 / S355J2W / Q460NH)
- Offshore structures
- Railway systems
- Industrial equipment
- Load-bearing steel structures
Sheet & Decorative Grades (A606 / thin weathering steel)
- Architectural panels
- Corrugated facades
- Landscaping design
- Decorative steel screens
