S550Q
1.8904Quenched and tempered fine-grained structural steel with minimum yield strength 550 MPa. Q designation indicates impact testing at room temperature. Intermediate strength grade between S500 and S620 in the EN 10025-6 series. Used for hydraulic supports, construction machinery, crane components, and heavy vehicle chassis where higher strength than S500 is needed.
Chemical composition comparison (wt%)
Side-by-side: S550Q (EN) (EN 10025-6:2004) vs ASTM
| Element | S550Q (EN) | ASTM | Overlap |
|---|---|---|---|
| C | ≤ 0.2% | — | — |
| Si | ≤ 0.8% | — | — |
| Mn | ≤ 1.7% | — | — |
| P | ≤ 0.025% | — | — |
| S | ≤ 0.015% | — | — |
| Cr | ≤ 1.5% | — | — |
| Mo | ≤ 0.7% | — | — |
| Ni | ≤ 2% | — | — |
| V | ≤ 0.12% | — | — |
| B | ≤ 0.005% | — | — |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 640–820 | MPa |
| Yield Strength | ≥ 550 | MPa |
| Elongation | ≥ 16 | % |
| impact_kv | ≥ 30 | J |
| Density | ≥ 7.85 | g/cm3 |
| Elastic Modulus | ≥ 210 | GPa |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| quenching | 880–940 °C | water | — | Quenched and tempered at mill |
| tempering | 550–680 °C | air | — | — |
Related materials
S960QL
1.8933Ultra-high-strength quenched and tempered fine-grained structural steel with minimum yield strength 960 MPa. QL designation indicates impact testing at -40°C. Used for mobile cranes, heavy lift equipment, offshore wind turbine towers, mining machinery, and weight-critical structural applications. Weldable with appropriate precautions (preheating, low hydrogen). Dramatically reduces component weight compared to conventional structural steels.
P355NH
1.0565Weldable fine-grained non-alloy steel for pressure vessels with minimum yield strength 355 MPa. NH designation indicates normalized condition with specified elevated temperature properties and impact testing at -20°C. Very widely used pressure vessel grade for boilers, storage tanks, heat exchangers, and pipes transporting hot liquids and pressurized gases. Good weldability and resistance to brittle cracking.
C45E
1.1191Unalloyed special steel with controlled chemistry (E grade) and 0.42–0.50% carbon. Tighter P and S limits than standard C45 for improved consistency. The most widely used medium-carbon steel for quenching and tempering. Good balance of strength (620–850 MPa QT) and toughness. Through-hardening up to ø60mm. Surface hardening by induction to HRC 58. Used for shafts, gears, bolts, connecting rods, crankshafts, and general machine parts.
Not sure which material fits?
🤖 Ask AI Advisor →All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.