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Q390B STRUCTURAL STEEL PLATE

Chemical element composition – hot-rolled Q390B low-alloy high-strength structural steel 🔍 Q390B Grade Lookup →

Product Overview

Q390B 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 390MPa (≤16mm) and enhanced strength compared to Q355 grades, it is widely used in building structures, heavy machinery, and engineering applications requiring higher load-bearing capacity. Q390B offers excellent weldability and formability for general fabrication and manufacturing.

Equivalent grades: Q390B ↔ Q355B (domestic), ASTM A572 Grade 55 (USA), EN 10025 S355J2 (Europe).

International Grade Comparison

Europe (EN 10025-2)

S355J2

Impact: -20°C (27J)

Yield: 355MPa

C: ≤0.22%

Si: ≤0.55%

Mn: ≤1.60%

P: ≤0.025%

S: ≤0.025%

Nb: ≤0.05%

V: ≤0.12%

Ti: ≤0.05%

USA (ASTM A572)

Gr.55

Impact: Not specified

Yield: 380MPa

C: ≤0.25%

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)

Q355B

Impact: 20°C (34J)

Yield: 355MPa

C: ≤0.20%

Si: ≤0.50%

Mn: 1.00-1.60%

P: ≤0.035%

S: ≤0.035%

Nb: ≤0.07%

V: ≤0.15%

Ti: ≤0.20%

Note: Q390B is functionally comparable to these international grades; always verify specific requirements before substitution.

China Grade Comparison: Q390B vs Q390C vs Q390D vs Q355B

Q390B

Grade B

Impact: 20°C

KV2 (L): 34J

C: ≤0.20%

P: ≤0.035%

S: ≤0.035%

Q390C

Grade C

Impact: 0°C

KV2 (L): 34J

C: ≤0.20%

P: ≤0.030%

S: ≤0.030%

Q390D

Grade D

Impact: -20°C

KV2 (L): 34J

C: ≤0.20%

P: ≤0.025%

S: ≤0.025%

Q355B

Grade B

Impact: 20°C

KV2 (L): 34J

Yield: 355MPa

C: ≤0.20%

P: ≤0.035%

S: ≤0.035%

Note: Q390 series grades share identical tensile properties (yield strength, tensile strength, elongation). The key differences are impact test temperature and corresponding impurity limits: B (20°C, 34J), C (0°C, 34J), D (-20°C, 34J). Q355B shown for comparison with lower yield strength.

Key Advantages

Excellent Weldability

Controlled carbon content (≤0.20%) and micro-alloying elements ensure good weldability for most applications without preheating.

High Strength

Minimum yield strength of 390MPa (≤16mm) and tensile strength 490-650MPa, ideal for high-load structural applications.

20°C Impact Toughness

Guaranteed impact energy of 34J at 20°C, suitable for general structural applications.

Applications

Building Structures

High-rise buildings, industrial plants, stadiums, steel frameworks

Heavy Machinery

Construction machinery, crane booms, mining equipment, heavy vehicles

Q390B Chemical Composition (GB/T 1591-2018)

Grade C Si Mn P S Nb V Ti Cr Ni Cu Mo N
Q390B ≤0.20 ≤0.55 ≤1.7 ≤0.035 ≤0.035 ≤0.05 ≤0.13 ≤0.05 ≤0.3 ≤0.5 ≤0.4 ≤0.1 ≤0.015

Notes: a. For thickness >100mm, carbon content negotiable. b. For thickness >30mm, carbon ≤0.22%. c. For structural steel and bars, P/S upper limit may increase by 0.005%. d. Maximum for Q390/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.

Q390B Mechanical 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 >250-400mm
Q390B 390 380 360 340 340 320 — — —

Tensile Strength Rm (MPa)

Grade ≤100mm >100-150mm >150-250mm >250-400mm
Q390B 490-650 470-620 — —

Impact Energy KV2 at 20°C (J) min.

Grade Longitudinal Transverse
Q390B 34 27

Notes: a. When yield strength not obvious, use Rp0.2. b. Values for thicker sections apply only to quality grade D plates. c. Applicable only to structural steel and bars.

Size & Specification

Product Form Thickness (mm) Width (mm) Length (mm)
Plate 3 - 300 1000 - 4000 3000 - 18000
Sheet / Coil 1.5 - 20 900 - 2000 Coil or cut to length

Other sizes available. Tolerances per GB/T 709.

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

Quality & Manufacturing Assurance

Modern Production

Advanced continuous casting and controlled rolling

In-process Inspection

Spectral analysis, mechanical testing, 20°C impact

Full Documentation

Mill Test Certificate EN 10204 3.1

Packaging & Logistics

  • Packaging: Steel plates bundled with steel straps on wooden skids. Coils wrapped with waterproof paper.
  • Marking: Each bundle marked with grade, size, heat number, weight.
  • Logistics: FOB, CIF, CFR from main Chinese ports. Lead time 25-35 days.

Request a Quote

Emails go directly to customize@cehesteel.com — reply within 2h.

Frequently Asked Questions

Carbon content? ≤0.20% with lower limit of 0.22% for thicker sections.
Weldability? Excellent weldability due to low carbon equivalent (Ceq ≤0.45).
Thickness range? Available from 3mm to 300mm in plate form.
Yield strength? Minimum 390MPa for thickness ≤16mm, decreasing with thickness.
Mill certificates? Yes, EN 10204 Type 3.1 or 3.2 available upon request.
MOQ? 5 tons for stock sizes, negotiable for mill production orders.