Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes - GB/T 1591
Complete material data sheet for Q420E steel according to GB/T 1591-2018, including chemical composition, mechanical and physical properties, international equivalents, and application guidance for LSAW pipes.
Hot rolling, controlled rolling, normalizing, thermo-mechanical controlled processing (TMCP)
- Phone : +8618037372205
- Email : [email protected]
- WhatsApp: Contact via Whtsapp
- WeChat: +8618037372205
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Introduction
Q420E is a high-strength low-alloy structural steel grade specified in Chinese standard GB/T 1591-2018. It offers a minimum yield strength of 420 MPa and excellent low-temperature toughness (≥34 J at -40°C), making it suitable for welded structures in cold climates. The steel is typically delivered in hot-rolled, controlled-rolled, or normalized condition with fine grain practice and microalloying elements such as Nb, V, Ti.
Key features:
- High strength and good weldability
- Low-temperature impact resistance down to -40°C
- Fine-grain microstructure for uniform properties
- Used in bridges, buildings, pressure vessels, and LSAW pipelines
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Chemical Composition
The chemical composition of Q420E steel is designed to ensure high strength, good weldability, and low-temperature toughness. Carbon equivalent (CEV) is controlled to facilitate welding. Maximum limits for sulfur and phosphorus are kept low to enhance ductility and impact properties. Microalloying elements Nb, V, and Ti are added for grain refinement and precipitation strengthening.
Values are according to GB/T 1591-2018.
| Element | Content (%) | Remarks |
|---|---|---|
| C | ≤0.18 | Max |
| Si | ≤0.50 | Max |
| Mn | 1.00 – 1.70 | Range |
| P | ≤0.020 | Max |
| S | ≤0.010 | Max |
| Nb | ≤0.07 | Max |
| V | ≤0.20 | Max |
| Ti | ≤0.20 | Max |
| Cr | ≤0.30 | Max |
| Ni | ≤0.50 | Max |
| Cu | ≤0.30 | Max |
| Mo | ≤0.10 | Max |
| N | ≤0.015 | Max |
| Als | ≥0.015 | Min, acid soluble Al |
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Thermal and Electrical Physical Properties
The following physical properties are typical for Q420E steel and may vary slightly depending on composition and condition. These values are not mandatory in the product standard but are widely accepted engineering references.
| Property | Typical Value | Unit | Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Modulus of Elasticity (E) | 206 | GPa | 20°C |
| Shear Modulus (G) | 79.3 | GPa | 20°C |
| Poisson's Ratio (ν) | 0.30 | – | – |
| Thermal Expansion Coefficient (α) | 12.0 × 10-6 | 1/K | 20 – 100°C |
| Thermal Expansion Coefficient (α) | 12.5 × 10-6 | 1/K | 20 – 200°C |
| Thermal Expansion Coefficient (α) | 13.1 × 10-6 | 1/K | 20 – 400°C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | 20°C |
| Specific Heat Capacity (Cp) | 460 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρe) | 0.22 × 10-6 | Ω·m | 20°C |
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Mechanical Properties
Mechanical properties of Q420E steel depend on the product thickness. The minimum upper yield strength (ReH), tensile strength (Rm), elongation after fracture (A), and impact energy (KV2) at -40°C are specified in GB/T 1591-2018. Bend test is required to verify formability.
The following values are for delivery condition (hot-rolled, controlled-rolled, or normalized) and apply to flat and long products.
| Property | Required Value | Unit | Condition/Thickness |
|---|---|---|---|
| Yield Strength (ReH) | ≥420 | MPa | thickness ≤ 16 mm |
| Yield Strength (ReH) | ≥400 | MPa | thickness 16 – 40 mm |
| Yield Strength (ReH) | ≥380 | MPa | thickness 40 – 63 mm |
| Yield Strength (ReH) | ≥360 | MPa | thickness 63 – 80 mm |
| Yield Strength (ReH) | ≥360 | MPa | thickness 80 – 100 mm |
| Yield Strength (ReH) | ≥340 | MPa | thickness 100 – 150 mm |
| Tensile Strength (Rm) | 520 – 680 | MPa | thickness ≤ 100 mm |
| Tensile Strength (Rm) | 510 – 670 | MPa | thickness 100 – 150 mm |
| Elongation (A) | ≥18 | % | thickness ≤ 40 mm |
| Elongation (A) | ≥18 | % | thickness 40 – 63 mm |
| Elongation (A) | ≥18 | % | thickness 63 – 80 mm |
| Elongation (A) | ≥18 | % | thickness 80 – 100 mm |
| Elongation (A) | ≥17 | % | thickness 100 – 150 mm |
| Impact Energy (KV2) | ≥34 | J | -40°C, longitudinal specimen |
| Bend Test (180°) | d = 3a (a ≤ 16 mm) | – | Bend diameter d, specimen thickness a |
| Bend Test (180°) | d = 4a (a > 16 mm) | – |
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Fully Equivalent Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-4 | S420ML | Thermo-mechanically rolled, impact energy ≥27 J at -50°C, similar strength and low-temperature properties. |
| Europe | EN 10025-3 | S420NL | Normalized fine grain steel, impact energy ≥27 J at -50°C, directly substitutable for Q420E. |
| International | ISO 630-2 | S420NL | Equivalent to EN S420NL, suitable for structural steel with -50°C impact. |
| USA | ASTM A572/A572M | Grade 60 [415] | 415 MPa minimum yield, impact toughness not specified; supplementary impact test at -40°C can make it comparable. |
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Application Introduction
Q420E is extensively used in load-bearing welded structures that require high strength, good weldability, and reliable toughness at sub-zero temperatures. It is especially suitable for LSAW (Longitudinal Submerged Arc Welded) pipes used in long-distance oil and gas transmission, offshore projects, and structural columns.
Application areas include:
Product Applications: Longitudinally Submerged Arc Welded (LSAW) pipes (OD 16''–64'', wall thickness up to 50 mm), Welded H-beams and other fabricated profiles, Bridge deck plates and box girders, Offshore platform legs and piles, Pressure vessel cylindrical shells, Heavy-duty structural frames
Processed into products: LSAW pipe sections for pipeline main lines, Gusset plates and connection plates in steel structures, Flanges and end caps for pressure vessels, Base plates and stiffeners in heavy machinery, Crane box sections, Offshore node cans
Application industries: Oil and gas pipeline (LSAW pipes for onshore and offshore transport), Construction and civil engineering (high-rise buildings, bridges, stadiums), Offshore and marine engineering (platforms, jack-up legs, wind turbine foundations), Heavy machinery manufacturing (crane booms, excavator arms), Pressure vessel and boiler components (shells, heads, where low-temperature toughness is needed), Shipbuilding (structural members of large vessels)
Q420E High-Strength Low-Alloy Structural Steel for LSAW Pipes Similar / Closely Related Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 1591 | Q420D | Same strength level, impact at -20°C instead of -40°C (≥34 J). Often used where lower toughness required. |
| China | GB/T 19879 | Q420GJE | High-strength structural steel for buildings, impact at -40°C, similar composition but with additional requirements for seismic performance. |
| Europe | EN 10025-3 | S420N | Normalized, impact at -20°C; less stringent low-temperature toughness. |
| Europe | EN 10025-4 | S420M | Thermo-mechanically rolled, impact at -20°C; suitable alternative where -40°C is not mandatory. |
| Japan | JIS G3106 | SM570 | 570 MPa tensile strength; similar yield (≥420 MPa), but impact test temperature is typically 0°C or –20°C based on agreement. |
Notes:
- All data are based on GB/T 1591-2018 (for rolled steels) and typical industry references.
- Q420E is not a standard pipe grade but commonly used to manufacture LSAW pipes when ordered with plate properties.
- Welding procedures must comply with the material's carbon equivalent (CEV typically ≤0.45) to avoid cold cracking.
- For LSAW pipe production, the steel plate is formed into a cylinder and welded longitudinally; post-weld heat treatment may be applied depending on application requirements.
- Share
