Q420C STRUCTURAL STEEL
Product Overview
Q420C is a Chinese grade low-alloy high-strength structural steel conforming to GB/T 1591-2018 standard. Grade C provides guaranteed impact toughness at 0°C. With minimum yield strength of 420MPa, it provides higher strength than Q390 series and is widely used in bridges, buildings, pressure vessels, and engineering structures requiring enhanced load-bearing capacity in moderate low-temperature conditions.
International Grade Comparison
Europe (EN 10025-3)
S420NL
Impact: -50°C (27J)
Yield: 420MPa
C: ≤0.20%
Si: ≤0.60%
Mn: 1.00-1.70%
P: ≤0.025%
S: ≤0.020%
Nb: ≤0.05%
V: ≤0.12%
Ti: ≤0.05%
USA (ASTM A656)
Gr.80
Impact: Not specified
Yield: 550MPa
C: ≤0.18%
Si: ≤0.60%
Mn: ≤1.65%
P: ≤0.025%
S: ≤0.025%
Nb: ≤0.05%
V: ≤0.15%
Ti: ≤0.05%
China (GB/T 1591)
Q390C
Impact: 0°C (34J)
Yield: 390MPa
C: ≤0.20%
Si: ≤0.55%
Mn: ≤1.70%
P: ≤0.030%
S: ≤0.030%
Nb: ≤0.05%
V: ≤0.13%
Ti: ≤0.05%
China Grade Comparison: Q390C vs Q420C vs Q460C
Q390C
Impact: 0°C
KV2 (L): 34J
Yield: 390MPa
P: ≤0.030%
S: ≤0.030%
Q420C
Impact: 0°C
KV2 (L): 34J
Yield: 420MPa
P: ≤0.030%
S: ≤0.030%
Q460C
Impact: 0°C
KV2 (L): 34J
Yield: 460MPa
P: ≤0.030%
S: ≤0.030%
Key Advantages
Higher Strength
Minimum yield strength of 420MPa (≤16mm) and tensile strength 520-680MPa, ideal for high-stress structural applications.
Good Weldability
Controlled carbon content and micro-alloying elements ensure good weldability for most fabrication processes.
0°C Impact Toughness
Grade C provides guaranteed impact energy of 34J at 0°C (longitudinal), suitable for moderate low-temperature applications.
Applications
Building Structures
High-rise buildings, industrial plants, stadiums, steel frameworks requiring higher strength.
Heavy Machinery
Construction machinery, crane booms, mining equipment, heavy vehicles requiring enhanced strength.
Q420C Chemical Composition (GB/T 1591-2018)
| Grade | Quality | C (≤40mm) | C (>40mm) | Si | Mn | P | S | Nb | V | Ti | Cr | Ni | Cu | Mo | N | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Q420 | C | 0.20 | 0.22 | 0.55 | 1.7 | 0.03 | 0.03 | 0.05 | 0.13 | 0.05 | 0.3 | 0.8 | 0.4 | 0.2 | 0.15 |
Notes:
a. For structural steel sections with nominal thickness greater than 100mm, carbon content can be negotiated.
b. For steel with nominal thickness greater than 30mm, carbon content shall not exceed 0.22%.
c. For structural steel and bars, phosphorus and sulfur upper limit can be increased by 0.005%.
d. The maximum percentage for Q390 and Q420 can reach 0.07%, for Q460 up to 0.11%.
e. Up to 0.2%.
f. If Als ≥0.015% or Alt ≥0.02%, nitrogen content not limited.
g. Applicable only to structural steel and bars.
Q420C Tensile Properties (GB/T 1591-2018)
| Upper yield strength ReH/MPa ≥ | |||||||||||||
| Grade | Quality | ≤16 | >16-40 | >40-63 | >63-80 | >80-100 | >100-150 | >150-200 | >200-250 | >250-400 | Tensile Strength Rm (MPa) | ||
| Q420 | C | 420 | 410 | 390 | 370 | 370 | 350 | — | — | — | 520-680 (≤100mm) / 500-650 (100-150mm) | ||
| Property | Thickness Range (mm) | Value |
| Tensile Strength Rm | ≤100mm | 520-680 MPa |
| Tensile Strength Rm | >100-150mm | 500-650 MPa |
| Elongation A % | ≤16mm | 19% |
| Elongation A % | 16-40mm | 19% |
| Elongation A % | 40-63mm | 19% |
| Elongation A % | 63-80mm | 18% |
| Elongation A % | 80-200mm | 18% |
| Impact Energy | Longitudinal | Transverse |
| KV2 (J) at 0°C | 34 | 27 |
Notes: a. When yield strength not obvious, use Rp0.2. b. Applicable only to structural steel and bars.
Customizable Options
We offer comprehensive customization services to meet your specific project requirements:
| Custom Dimensions Non-standard sizes, laser cutting |
Surface Treatments Shot blasting, priming |
Edge Preparation Beveling, machining |
| Custom Heat Treatment Normalizing, stress relieving |
Special Testing Third-party inspection |
Custom Marking Special labeling |
Size & Specification
| Product Form | Thickness (mm) | Width (mm) | Length (mm) |
| Plate | 3 - 150 | 1000 - 4000 | 3000 - 18000 |
| Sheet / Coil | 1.5 - 20 | 900 - 2000 | Coil or cut to length |
Other sizes can be produced upon request. Custom cutting available.
Quality & Manufacturing Assurance
Modern Production
Advanced continuous casting and controlled rolling technology
In-process Inspection
Rigorous testing at each stage, including spectral analysis and impact testing at 0°C
Full Documentation
Mill Test Certificate (MTC) compliant with EN 10204 3.1/3.2
Packaging & Logistics
- Packaging: Steel plates bundled with steel straps on wooden skids. Coils wrapped with waterproof paper and steel covers.
- Marking: Each bundle/coil marked with grade, size, heat number, weight.
- Logistics: FOB, CIF, CFR from main Chinese ports. Lead time 25-35 days after order.
Request a Quote
Emails go directly to customize@cehesteel.com — reply within 2h.
Frequently Asked Questions
Q420C is a hot-rolled low-alloy structural steel per GB/T 1591-2018 with 420MPa min yield and 34J impact at 0°C.
Q420C is comparable to Q390C (domestic), S420NL (Europe), and ASTM A656 Gr.80 (USA).
Good weldability with appropriate procedures due to controlled chemistry and low carbon content.
3mm to 150mm plates, 1.5-20mm coils/sheets with custom cutting available.
Yes, EN 10204 3.1 MTC with full data including 0°C impact test results.
Standard 5 tons. Sample orders possible.