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Q420B STRUCTURAL STEEL

Chemical element composition – Chinese grade Q420B low alloy high strength structural steel 🔍 Q420B Grade Lookup →

Product Overview

Q420B is a Chinese grade low-alloy high-strength structural steel conforming to GB/T 1591-2018 standard. Grade B provides guaranteed impact toughness at 20°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.

Equivalent grades: Q420B ↔ Q390B (lower strength domestic), EN 10025 S460JR (Europe), ASTM A572 Grade 60 (USA).

International Grade Comparison

Europe (EN 10025-2)

S460JR

Impact: 20°C (27J)

Yield: 460MPa

C: ≤0.22%

Si: ≤0.60%

Mn: ≤1.80%

P: ≤0.030%

S: ≤0.030%

Nb: ≤0.05%

V: ≤0.12%

Ti: ≤0.05%

USA (ASTM A572)

Gr.60

Impact: Not specified

Yield: 415MPa

C: ≤0.26%

Si: ≤0.40%

Mn: ≤1.35%

P: ≤0.025%

S: ≤0.025%

Nb: ≤0.05%

V: ≤0.15%

Ti: ≤0.05%

China (GB/T 1591)

Q390B

Impact: 20°C (34J)

Yield: 390MPa

C: ≤0.20%

Si: ≤0.55%

Mn: ≤1.70%

P: ≤0.035%

S: ≤0.035%

Nb: ≤0.05%

V: ≤0.13%

Ti: ≤0.05%

Note: Q420B offers higher strength than Q390B and is comparable to S460JR and ASTM A572 Grade 60; always verify specific requirements before substitution.

China Grade Comparison: Q420B vs Q420C vs Q420D vs Q420E

Q420B

Grade B

Impact: 20°C

KV2 (L): 34J

P: ≤0.035%

S: ≤0.035%

Q420C

Grade C

Impact: 0°C

KV2 (L): 34J

P: ≤0.030%

S: ≤0.030%

Q420D

Grade D

Impact: -20°C

KV2 (L): 34J

P: ≤0.030%

S: ≤0.025%

Q420E

Grade E

Impact: -40°C

KV2 (L): 27J

P: ≤0.025%

S: ≤0.020%

Note: Q420 series grades share similar tensile properties. The key differences are impact test temperature and impurity limits: B (20°C, 34J, P≤0.035%, S≤0.035%), C (0°C, 34J, P≤0.030%, S≤0.030%), D (-20°C, 34J, P≤0.030%, S≤0.025%), E (-40°C, 27J, P≤0.025%, S≤0.020%).

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.

20°C Impact Toughness

Grade B provides guaranteed impact energy of 34J at 20°C (longitudinal), suitable for general 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.

Q420B Chemical Composition (GB/T 1591-2018)

Grade Quality C Si Mn P S
Q420 B ≤0.20 ≤0.55 ≤1.7 ≤0.035 ≤0.035
Nb V Ti Cr Ni Cu Mo N Als (min)
≤0.05 ≤0.13 ≤0.05 ≤0.3 ≤0.8 ≤0.4 ≤0.2 ≤0.015 ≥0.015

Notes:

a. For bars, P/S upper limit +0.005%.

b. V+Nb+Ti ≤0.22%, Mo+Cr ≤0.30%.

c. Ti up to 0.20% maximum.

d. Alt (total aluminum) can substitute Als with minimum 0.020%. When Nb/V/Ti added at specified levels, Als lower limit not required.

e. Steel must contain at least one grain-refining element (Al, Nb, V, Ti) with content not less than specified minimum.

Q420B Tensile Properties (GB/T 1591-2018)

Upper yield strength ReH/MPa ≥
Grade ≤16mm 16-40mm 40-63mm 63-80mm 80-100mm 100-150mm 150-200mm 200-250mm
Q420B 420 400 390 370 360 340 330 320
Property Thickness Range Value
Tensile Strength Rm ≤100mm 520-680 MPa
100-200mm 500-650 MPa
200-250mm 500-650 MPa
Elongation A % ≤16mm 19%
16-40mm 19%
40-63mm 19%
63-80mm 18%
80-200mm 18%
200-250mm 18%
Impact Energy Longitudinal Transverse
KV2 (J) at 20°C 34 27

Notes: When yield not obvious, use Rp0.2.

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 - 250 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 20°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

What is Q420B?

Q420B is a hot-rolled low-alloy structural steel per GB/T 1591-2018 with 420MPa min yield and 34J impact at 20°C.

What are the equivalents of Q420B?

Q420B is comparable to Q390B (domestic), EN 10025 S460JR (Europe), and ASTM A572 Grade 60 (USA).

Weldability?

Good weldability with appropriate procedures due to controlled chemistry and low carbon content.

Available thickness?

3mm to 250mm plates, 1.5-20mm coils/sheets with custom cutting available.

Mill certificates?

Yes, EN 10204 3.1 MTC with full data including 20°C impact test results.

Difference between B, C, D, E?

Impact temperature: B (20°C), C (0°C), D (-20°C), E (-40°C) with tightening impurity limits.