DIN 1629 ST37.0 Seamless Circular Tubes Material
ST37.0 Seamless Circular Tube (DIN 1629) – Non-Alloy Steel Properties, Equivalents & Applications
Explore the complete technical data sheet for ST37.0 seamless circular tubes under DIN 1629, covering chemical composition, mechanical and thermal properties, international equivalents, and typical applications in structural and mechanical engineering.
Hot rolling, cold drawing, normalizing, machining, welding (for further fabrication)
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DIN 1629 ST37.0 Seamless Circular Tubes Introduction
ST37.0 is a non-alloy structural steel grade defined in the German standard DIN 1629, which specifies seamless circular tubes made from unalloyed steels with special quality requirements. This material is widely used for general engineering and structural applications due to its balanced combination of good weldability, adequate strength, and excellent formability. The tubes are typically supplied in the hot-rolled or normalized condition. Key features:
- Minimum yield strength of 235 MPa for wall thickness up to 16 mm
- Tensile strength range of 350–480 MPa
- Good ductility with elongation values not less than 25% (longitudinal)
- Supplied with special quality requirements ensuring reliable performance in load-bearing structures
DIN 1629 ST37.0 Seamless Circular Tubes Chemical Composition
The chemical composition of ST37.0 is defined by DIN 1629 to ensure good weldability and mechanical properties. The steel is unalloyed with controlled levels of carbon, manganese, and impurities such as phosphorus and sulfur. Aluminum may be added for grain refinement but is not mandatory. All values are maximum unless a range is indicated.
| Element | Requirement (%) | Remarks |
|---|---|---|
| C (Carbon) | ≤ 0.17 | Max. for heat analysis |
| Si (Silicon) | ≤ 0.35 | Max. for heat analysis |
| Mn (Manganese) | ≥ 0.35 | Min. for heat analysis; no max. specified but typically ≤ 1.20 |
| P (Phosphorus) | ≤ 0.040 | Max. for heat analysis |
| S (Sulfur) | ≤ 0.040 | Max. for heat analysis |
| Al (Aluminum) | ≤ 0.020 | Optional; if added for killing, aluminium content is limited to this value (total Al) |
DIN 1629 ST37.0 Seamless Circular Tubes Thermal and Electrical Physical Properties
The following physical properties are representative for non-alloy carbon steels such as ST37.0 at room temperature unless stated otherwise. These values are typical and not specified in DIN 1629, but they are essential for design calculations. Actual values may vary slightly with specific heat treatment and composition.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Modulus of Elasticity (E) | 210 | GPa | 20 °C |
| Shear Modulus (G) | 81 | GPa | 20 °C |
| Poisson's Ratio (ν) | 0.30 | – | 20 °C |
| Thermal Expansion Coefficient (α) | 11.1 × 10⁻⁶ | /K | 20 – 100 °C |
| Thermal Conductivity (λ) | 53 | W/(m·K) | 20 °C |
| Specific Heat Capacity (c) | 460 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρe) | 0.15 | Ω·mm²/m | 20 °C |
DIN 1629 ST37.0 Seamless Circular Tubes Mechanical Properties
Mechanical properties of ST37.0 tubes are guaranteed in the delivery condition (as-rolled or normalized). The values depend on wall thickness. Tensile testing is performed on longitudinal or transverse test pieces. Bending test with a mandrel is required for tubes as a quality control. The minimum yield strength applies for thickness ≤ 16 mm.
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 235 | MPa | Wall thickness t ≤ 16 mm |
| Yield Strength (ReH) | ≥ 225 | MPa | Wall thickness 16 < t ≤ 40 mm |
| Tensile Strength (Rm) | 350 – 480 | MPa | All thicknesses |
| Elongation (A) | ≥ 25 | % | Longitudinal test piece, gauge length 5.65√S₀ (A5) |
| Elongation (A) | ≥ 23 | % | Transverse test piece, A5 |
| Bend Test | No cracks | – | Bend angle 180°, mandrel diameter 0.5 × wall thickness (t ≤ 40 mm) |
DIN 1629 ST37.0 Seamless Circular Tubes Equivalent Material Standards and Substitutible Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10210-1 | S235JRH | Hot finished structural hollow sections; direct technical equivalent for seamless circular tubes |
| USA | ASTM A53 | Grade B | Seamless and welded pipe for mechanical and pressure applications; similar chemical and mechanical requirements |
| Japan | JIS G3444 | STK400 | Carbon steel tubes for general structural purposes; comparable strength level |
| International | ISO 630 | Fe 360B | Structural steel plates; not a tube standard but shares chemical and strength characteristics |
DIN 1629 ST37.0 Seamless Circular Tubes Application Introduction
ST37.0 seamless tubes under DIN 1629 are versatile and cost-effective structural materials. Their combination of moderate strength, excellent weldability, and reliable quality makes them suitable for a wide range of demanding environments. They are commonly used where the joint efficiency of welded connections is critical, and where pressure tightness is not a primary design requirement.
- Ideal for lightweight frames and trusses
- Extensively used in hot-dip galvanized structures for corrosion resistance
- Machinable and cold-formable for precision components
Product Applications: Structural framing systems, Roll cages and chassis members, Transmission towers and lighting poles, Greenhouse frames, Conveyor rollers, Bicycle frames and motorcycle components
Processed into products: Round tubular sections (welded into assemblies), Turned and milled sleeves and bushings, Cold-drawn precision spacers, Flanged pipe connectors (where pressure code does not apply), Drilled and slotted structural connectors, Bent arches and handrailing systems
Application industries: Construction and civil engineering, Automotive and transportation, Agricultural machinery, General mechanical engineering, Furniture and scaffold manufacturing, Heating and ventilation (non-pressure parts)
DIN 1629 ST37.0 Seamless Circular Tubes Similar or Closely Related Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Germany | DIN 17100 | ST37-2 | General structural steel (plates, sections) with same base designation; slightly broader composition limits |
| European Union | EN 10025-2 | S235JR | Hot-rolled structural steel; very similar chemical composition and mechanical properties |
| China | GB/T 700 | Q235B | Chinese carbon structural steel; analogous strength and weldability |
| USA | ASTM A36 | A36 | Common structural steel; comparable mechanical range but used mainly for shapes and plates |
Notes:
Special quality requirements: DIN 1629 stipulates that ST37.0 tubes are suitable for welding and general structural applications, but they are not intended for pressure purposes. For pressurized systems, refer to DIN 1626 (welded) or DIN 17175 (seamless) grades. Welding: Readily welded by all common methods; preheating not required for thin sections. Dimensional tolerances: Governed by DIN 1629 Part 2; outside diameter typically ±1% with minimum ±0.5 mm. Certification: Inspection certificate 3.1 according to EN 10204 is standard.
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