DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel for Automobile Structures
Detailed properties and chemical composition of StE420 steel according to DIN 17102, a fine-grain structural steel used in automobile engineering and heavy vehicle chassis components.
Normalizing (+N) or thermo-mechanical rolling (+M); suitable for cold forming, bending, welding, cutting, machining
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DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Introduction
StE420 is a weldable fine-grain structural steel defined under the German standard DIN 17102, specifically designed for automobile structures and other dynamically loaded welded constructions. This steel is characterized by a minimum yield strength of 420 MPa in thicknesses up to 16 mm. It achieves its high strength and excellent toughness through grain refinement by microalloying elements (Nb, V, Ti) and a controlled rolling or normalizing process.
The steel offers a good combination of high load-bearing capacity, good weldability, and reliable low-temperature impact properties, making it suitable for critical safety components in trucks, trailers, and heavy machinery.
- Minimum yield strength: 420 MPa (t ≤ 16 mm)
- Good cold forming and bending properties
- Excellent weldability with low carbon equivalent
- Available as normalized or thermo-mechanically rolled
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Chemical Composition
The chemical composition of StE420 is controlled to ensure high strength and good weldability. Maximum limits are given for most elements, while the total content of grain-refining elements (Nb, V, Ti) is restricted. The carbon equivalent (CEV) is also limited to guarantee crack-free welding.
| Element | Standard Value | Remarks |
|---|---|---|
| C | ≤ 0.20 | Max |
| Si | ≤ 0.50 | Max |
| Mn | 1.00 – 1.70 | Range |
| P | ≤ 0.035 | Max |
| S | ≤ 0.030 | Max |
| Al (total) | ≥ 0.020 | Min, for fine grain |
| N | ≤ 0.015 | Max |
| Nb1 | ≤ 0.05 | Grain refiner |
| V1 | ≤ 0.10 | Grain refiner |
| Ti1 | ≤ 0.10 | Grain refiner |
| CEV | ≤ 0.45 | Carbon equivalent, for t ≤ 40 mm |
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Thermal and Electrical Physical Properties
The following physical properties are typical for low-carbon microalloyed steel and are not mandatory requirements of the standard. They provide useful values for engineering calculations.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At room temperature |
| Modulus of elasticity (E) | 210 | GPa | At 20 °C |
| Shear modulus (G) | 81 | GPa | At 20 °C |
| Poisson's ratio (ν) | 0.3 | – | At 20 °C |
| Thermal expansion (α) | 11.1 | 10⁻⁶ /K | Between 20 °C and 100 °C |
| Thermal expansion (α) | 12.5 | 10⁻⁶ /K | Between 20 °C and 200 °C |
| Thermal conductivity (λ) | 45 | W/(m·K) | At 20 °C |
| Specific heat capacity | 460 | J/(kg·K) | At 20 °C |
| Electrical resistivity (ρₑ) | 0.22 | µΩ·m | At 20 °C |
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Mechanical Properties
Mechanical properties are guaranteed for specified thickness ranges in the normalized or thermo-mechanically rolled condition. The values below meet the requirements of DIN 17102 StE420. Impact properties are determined on Charpy-V specimens at different temperatures.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield strength (ReH) | ≥ 420 | MPa | Thickness ≤ 16 mm |
| Yield strength (ReH) | ≥ 400 | MPa | Thickness > 16 ≤ 40 mm |
| Yield strength (ReH) | ≥ 370 | MPa | Thickness > 40 ≤ 63 mm |
| Tensile strength (Rm) | 520 – 680 | MPa | All thicknesses ≤ 63 mm |
| Elongation (A5) | ≥ 19 | % | Longitudinal, t ≤ 40 mm |
| Elongation (A5) | ≥ 14 | % | Transverse, t ≤ 40 mm |
| Impact energy (KV2) | ≥ 27 | J | At 0 °C, longitudinal (StE420) |
| Impact energy (KV2) | ≥ 27 | J | At -20 °C, longitudinal (StE420 L) |
| Bend test (mandrel dia.) | 3t (t ≤ 16 mm) | – | 180° bend, d = 3 × thickness |
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Fully Equivalent Material Standards and Alternative Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Germany | DIN 17102 | StE420 | Original standard, normalized or thermo-mechanically rolled |
| European Union | EN 10025-3 | S420N | Normalized fine-grain structural steel, same yield class |
| European Union | EN 10025-4 | S420M | Thermo-mechanically rolled, same strength level |
| United States | ASTM A572 | Grade 60 | High-strength low-alloy structural steel (yield ≥ 415 MPa) |
| Japan | JIS G3106 | SM490YA | Welded structural steel with min. 490 N/mm² tensile, approximate |
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Application Introduction
StE420 is optimized for dynamically loaded welded structures in the automotive and heavy machinery industries. It is used where weight reduction and high fatigue resistance are critical. Typical processing includes thermal cutting, cold forming (bending, roll forming), and subsequent welding. The fine-grain structure ensures consistent mechanical properties after forming and welding, with minimal risk of brittle fracture.
Product Applications: Heavy-duty transport welded steel pipes, Welded H-beams and box sections, Wear-resistant bucket tooth, Hydraulic cylinder bracket, Bridge bearing structures
Processed into products: Truck frame side rails and cross members, Trailer chassis and gooseneck beams, Container underframes and lifting lugs, Excavator booms and arms, Press brake formed structural brackets
Application industries: Automotive manufacturing (truck, bus, trailer), Construction and earth-moving machinery, Crane and lifting equipment, Pressure vessel and tank production, Offshore and shipbuilding (secondary structures)
DIN 17102 StE420 High-Strength Weldable Fine-Grain Structural Steel Recommended Similar / Alternate Materials
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 1591 | Q420ND | Normalized fine-grain steel, comparable yield and toughness |
| Russia | GOST 19281 | 10ChSND (grade 345-420) | Similar strength low-alloy steel |
| International | ISO 4951 | S420N | ISO equivalent to S420N in EN standards |
Notes:
This steel can be supplied with optional ultrasonic testing according to EN 10160. For welded structures, preheating and interpass temperature control is recommended when ambient temperature is below +5 °C. The CEV value given in the chemical composition is based on ladle analysis; product analysis may have slightly higher limits per standard. When ordering StE420 to DIN 17102, the delivery condition (+N or +M) and any supplementary requirements (e.g., impact temperature class L for -20 °C) must be specified.
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