Home › Structural Steel › Q390NB Steel Plate

Q390NB STRUCTURAL STEEL

Chemical element composition – Chinese grade Q390NB low alloy high strength structural steel 🔍 Q390NB Grade Lookup →

Product Overview

Q390NB is a Chinese grade low-alloy high-strength structural steel conforming to GB/T 1591-2018 standard. It features a normalized or normalized plus tempered delivery condition, offering improved toughness and consistent properties. With minimum yield strength of 390MPa, it provides higher strength than Q355 series and is widely used in bridges, buildings, pressure vessels, and engineering structures requiring enhanced load-bearing capacity.

Chinese Standard GB/T 1591-2018: Q390NB is a normalized grade with 20°C impact toughness. The "N" denotes normalized delivery condition, offering improved grain refinement compared to as-rolled grades.

International Grade Comparison

Europe (EN 10025-3)

S420N

Impact: -20°C (40J)

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 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%

Note: Q390NB is a normalized grade comparable to S420N in delivery condition and to A572 Gr.60 in strength level; always verify specific requirements before substitution.

China Grade Comparison: Q390B vs Q355NB vs Q420NB

Q390B

Hot-Rolled Grade

Yield: 390MPa

Impact (20°C): 34J

Delivery: As-rolled

P: ≤0.035%

S: ≤0.035%

Q355NB

Normalized Grade

Yield: 355MPa

Impact (20°C): 34J

Delivery: Normalized

P: ≤0.035%

S: ≤0.035%

Q390NB

Normalized Grade

Yield: 390MPa

Impact (20°C): 34J

Delivery: Normalized

P: ≤0.035%

S: ≤0.035%

Q420NB

Normalized Grade

Yield: 420MPa

Impact (20°C): 34J

Delivery: Normalized

P: ≤0.035%

S: ≤0.035%

Note: Q390NB and Q390B share identical mechanical properties (yield strength, tensile strength, elongation, impact energy). The key difference is the delivery condition: Q390NB is normalized or normalized plus tempered, providing improved grain refinement and more consistent properties throughout the thickness, while Q390B is as-rolled. Q355NB and Q420NB are other normalized grades with different strength levels.

Key Advantages

Higher Strength

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

Normalized Condition

Delivered in normalized or normalized plus tempered state for improved grain refinement and consistent mechanical properties.

Enhanced Toughness

Grain-refining elements (Al, Nb, V, Ti) ensure excellent impact toughness at 20°C with 34J guaranteed.

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.

Q390NB Chemical Composition (GB/T 1591-2018)

Grade Quality C Si Mn P S
Q390N B ≤0.20 ≤0.50 0.90-1.70 ≤0.035 ≤0.035
Nb V Ti Cr Ni Cu Mo N Als (min)
0.01-0.05 0.01-0.20 0.006-0.05 ≤0.3 ≤0.5 ≤0.4 ≤0.1 ≤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.

Q390NB 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
Q390NB 390 380 360 340 340 320 310 300
Property Thickness Range Value Impact Energy (20°C)
Tensile Strength Rm ≤100mm 490-650 MPa 34J (Longitudinal)
27J (Transverse)
100-200mm 470-620 MPa
200-250mm 470-620 MPa
Elongation A % ≤16mm 20%
16-40mm 20%
40-63mm 20%
63-80mm 19%
80-200mm 19%
200-250mm 19%

Notes: Normalized condition includes normalized and tempered condition. 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 normalized heat treatment for optimal grain refinement

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 Q390NB?

A normalized low-alloy structural steel per GB/T 1591-2018, with min yield 390MPa and 20°C impact toughness.

Weldability?

Good weldability with appropriate procedures due to controlled chemistry and fine-grain normalized structure.

Available thickness?

3mm to 250mm plates, 1.5-20mm coils/sheets.

Micro-alloying elements?

Contains Nb (0.01-0.05%), V (0.01-0.20%), Ti (0.006-0.05%), with Als ≥0.015% for grain refinement.

Mill certificates?

Yes, EN 10204 3.1 MTC with full mechanical and chemical data, including normalized condition verification.

MOQ?

Standard 5 tons. Sample orders (1-2 tons) possible.

Difference between NB and B?

Same chemical composition and mechanical properties. "N" indicates normalized delivery condition, providing improved grain refinement and consistent properties through thickness.