1. **Hardness of ST37 Steel**
ST37 steel (a common structural steel in Europe, equivalent to S235JR) typically has a Brinell hardness (HB) of approximately **120–160 HB**, depending on heat treatment and thickness. It is not a high-hardness steel, as it prioritizes ductility and weldability for structural applications.
2. **Difference Between A36 and ST37**
- **A36 (ASTM standard, USA):** Minimum yield strength of 250 MPa (36 ksi), with slightly higher carbon content.
- **ST37 (DIN/EN standard, Europe):** Minimum yield strength of 235 MPa, better suited for cold-forming.
- **Applications:** A36 is widely used in the U.S., while ST37 is common in Europe. Both are general-purpose structural steels, but ST37 offers better elongation (ductility).
3. **Toughness of ST37**
ST37 has moderate toughness, suitable for static loads and mild dynamic stresses. Its Charpy V-notch impact energy at room temperature is around **27–40 Joules**, depending on the grade (e.g., ST37-2 or ST37-3). It is not recommended for low-temperature or high-impact environments without additional testing.
4. **Price of ST37 Material**
As of 2023, ST37 steel costs approximately **$600–$900 per metric ton**, varying by region, supplier, and form (sheet, plate, bar). Prices fluctuate with raw material markets (iron ore, energy) and demand.
5. **Allowable Stress for Steel 37 (ST37)**
Allowable stress depends on the design code (e.g., Eurocode, DIN). For ST37 (S235JR):
- **Tensile stress (safe load):** ~140–160 MPa (safety factor applied to yield strength).
- **Compression/bending:** Similar range, adjusted for buckling risk. Always consult engineering standards for specific applications.
