ASTM A572 Grade 50 ERW Pipe
ASTM A572 Grade 50 ERW Pipe: High-Strength Low-Alloy Structural Steel for Welded Tubes
Explore the chemical, mechanical and physical properties of ASTM A572 Grade 50 steel used for electric-resistance-welded (ERW) pipe, including international equivalents and typical applications.
Suitable for all common welding methods, cutting, cold forming, and hot bending. ERW pipe is manufactured by cold forming and electric resistance welding of strip.
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ASTM A572 Grade 50 ERW Pipe Introduction
ASTM A572 Grade 50 is a high-strength low-alloy (HSLA) structural steel with a minimum yield strength of 50 ksi (345 MPa). It is widely used in welded structural applications, including ERW (Electric Resistance Welded) pipe. The material offers an excellent combination of strength, weldability, and notch toughness, making it suitable for bridges, buildings, and heavy machinery. The controlled chemistry with micro-alloying elements such as niobium or vanadium enables fine grain structure and improved mechanical properties without the need for heat treatment beyond normalizing rolling. ERW pipe produced from A572 Grade 50 sheets or coils retains the same strength and ductility as the parent material and is commonly supplied in the as-rolled or normalized condition.
ASTM A572 Grade 50 ERW Pipe Chemical Composition
The chemical composition of ASTM A572 Grade 50 is designed to meet the specified mechanical properties. Maximum contents are given for carbon, manganese, phosphorus, and sulfur. Silicon is required for deoxidation when the steel is killed, and micro-alloying elements like niobium and vanadium are added optionally for grain refinement.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | 0.23 max | For plates and shapes ≤ 1.5 in. (40 mm) |
| Manganese (Mn) | 1.35 max | For thicknesses up to 1.5 in. (40 mm) |
| Phosphorus (P) | 0.030 max | |
| Sulfur (S) | 0.030 max | |
| Silicon (Si) | 0.15 – 0.40 | Required for killed steel; max 0.40 for shapes |
| Niobium (Nb) | 0.05 max | Optional grain refiner; when added |
| Vanadium (V) | 0.08 max | Optional grain refiner; when added |
| Titanium (Ti) | 0.02 max | Residual, if not intentionally added |
| Copper (Cu) | 0.20 min if specified | When copper-bearing steel is ordered |
ASTM A572 Grade 50 ERW Pipe Thermal and Electrical Physical Properties
These physical properties are typical for low-carbon, low-alloy structural steels and apply to ASTM A572 Grade 50 ERW pipe. The actual values may vary slightly with temperature and processing conditions.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | at 20 °C |
| Modulus of Elasticity (E) | 200 | GPa | at 20 °C |
| Shear Modulus (G) | 80 | GPa | at 20 °C |
| Poisson's Ratio (ν) | 0.30 | — | at 20 °C |
| Thermal Expansion Coefficient (α) | 11.7 | 10⁻⁶/K | 20–100 °C |
| Thermal Conductivity (λ) | 51.9 | W/(m·K) | at 100 °C |
| Specific Heat Capacity (cp) | 486 | J/(kg·K) | 0–100 °C |
| Electrical Resistivity (ρe) | 0.142 | µΩ·m | at 20 °C |
ASTM A572 Grade 50 ERW Pipe Mechanical Properties
Tensile and elongation requirements for ASTM A572 Grade 50 plates and bars are applied here to ERW pipe because the pipe is manufactured from the same grade of steel strip. Values depend on the wall thickness. The yield and tensile strengths are independent of thickness up to 4 in. (100 mm).
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 345 | MPa | All thicknesses up to 100 mm |
| Tensile Strength (Rm) | ≥ 450 | MPa | All thicknesses up to 100 mm |
| Elongation (A) in 50 mm gauge | ≥ 21 | % | Thickness ≤ 19 mm |
| Elongation (A) in 50 mm gauge | ≥ 21 | % | Thickness 19–32 mm |
| Elongation (A) in 50 mm gauge | ≥ 18 | % | Thickness 32–64 mm |
| Elongation (A) in 50 mm gauge | ≥ 17 | % | Thickness 64–100 mm |
| Elongation (A) in 200 mm gauge | ≥ 18 | % | Thickness ≤ 19 mm |
| Elongation (A) in 200 mm gauge | ≥ 18 | % | Thickness 19–32 mm |
| Elongation (A) in 200 mm gauge | ≥ 16 | % | Thickness 32–64 mm |
| Elongation (A) in 200 mm gauge | ≥ 15 | % | Thickness 64–100 mm |
ASTM A572 Grade 50 ERW Pipe Completely Equivalent Material Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-2 | S355J0 / S355J2 | Minimum yield strength 355 MPa; close match in chemical and mechanical properties; J2 includes impact test down to -20 °C. |
| Japan | JIS G 3106 | SM490A | Yield strength 325–365 MPa (thickness dependent); suitable for welded structures. |
| China | GB/T 1591 | Q355D | Equivalent to S355; offers low-temperature impact properties; widely used in construction. |
| International | ISO 630 | Fe 510B | Former designation; minimum yield 355 MPa; structural quality. |
ASTM A572 Grade 50 ERW Pipe Application Introduction
ASTM A572 Grade 50 ERW pipe combines high strength, excellent weldability, and good formability. It is used in a wide range of structural and mechanical applications where weight savings and toughness are critical. The pipe can be further processed by cold bending, cutting, drilling, and welding.
Product Applications: Structural hollow sections (square, rectangular, round ERW pipe), Pipe piling for foundations, Bollards and guardrail posts, Poles for lighting, traffic signals, and utilities, Conveyor rollers and machinery frames, Water and gas transmission pipes (subject to coating/lining requirements)
Processed into products: Column and beam sections in steel frameworks, Tower legs and lattice members, Welded pipe trusses, Trailer chassis and frame rails, Railing and handrail posts, Shoring and scaffolding components, Shafts and sleeves in industrial machinery
Application industries: Structural engineering and construction, Bridge building, Heavy machinery and equipment manufacturing, Transmission and telecommunication towers, Piling and foundation works, Oil and gas distribution (non-sour service), Agricultural and transport equipment
ASTM A572 Grade 50 ERW Pipe Similar / Closely Related Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A572 | Grade 55 | Higher strength (380 MPa yield) but otherwise similar chemistry and weldability. |
| USA | ASTM A500 | Grade C | Standard specification for cold-formed welded structural tubing; similar strength (345 MPa yield) but for direct pipe/tube products. |
| USA | ASTM A36 | — | Lower strength (250 MPa yield) structural steel; often used where A572 Grade 50 is over-specified; still widely weldable. |
| Europe | EN 10025-2 | S275J0 | Lower yield (275 MPa) alternative for less demanding structural applications. |
Notes:
ASTM A572 Grade 50 is not inherently a pipe specification; it describes the steel plate or strip from which ERW pipes are manufactured. The pipe itself may be covered by standards such as ASTM A139, ASTM A252 (for piling), or customized structural tube specifications. When ordering ERW pipe in this grade, supplementary requirements for impact testing, weld seam heat treatment, or tighter tolerances should be agreed upon between the buyer and the manufacturer.
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