ASTM A500

Product introduction

ASTM A500 Steel: Material Analysis and Mechanical Properties

1. Material Overview

ASTM A500 is the standard specification for cold-formed welded and seamless carbon steel structural tubing in rounds and shapes. This specification covers high-strength, low-alloy steel tubing used primarily for structural applications where strength-to-weight ratio and appearance are important considerations.

2. Chemical Composition Requirements

Element	Grade A %	Grade B %	Grade C %	Grade D %	Notes
Carbon (C)	≤ 0.26	≤ 0.26	≤ 0.23	≤ 0.27	Maximum limits
Manganese (Mn)	-	-	≤ 1.35	≤ 1.35	Grade C and D only
Phosphorus (P)	≤ 0.035	≤ 0.035	≤ 0.035	≤ 0.035	Impurity control
Sulfur (S)	≤ 0.035	≤ 0.035	≤ 0.035	≤ 0.035	Impurity control
Copper (Cu)	≥ 0.20	≥ 0.20	≥ 0.20	≥ 0.20	For atmospheric corrosion resistance

Note: ASTM A500 is primarily a mechanical property specification. Chemical composition requirements are minimal, with mechanical properties being the primary control point.

3. Mechanical Properties by Grade and Shape

Property	Grade A	Grade B	Grade C	Grade D	Shape Type
Tensile Strength, min	45,000 psi (310 MPa)	58,000 psi (400 MPa)	62,000 psi (427 MPa)	58,000 psi (400 MPa)	All shapes
Yield Strength, min	33,000 psi (228 MPa)	42,000 psi (290 MPa)	46,000 psi (317 MPa)	36,000 psi (248 MPa)	All shapes
Elongation in 2"	25%*	23%*	21%*	23%*	Varies by shape
Rectangular: YS min	39,000 psi (269 MPa)	46,000 psi (317 MPa)	50,000 psi (345 MPa)	36,000 psi (248 MPa)	Rectangular only
Round & Square: YS min	33,000 psi (228 MPa)	42,000 psi (290 MPa)	46,000 psi (317 MPa)	36,000 psi (248 MPa)	Round & Square

Note: Elongation requirements vary with wall thickness and shape. Values shown are for thickness ≤ 0.120".

4. Strength Progression Across Grades

Yield Strength Comparison (Rectangular Tubing)
↑ Yield Strength (ksi)
|
|55 ┼                                  ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ [Grade C]
|   |                                  |
|50 ┼                         ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
|   |                         |        |
|45 ┼▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ [Grade B]
|   |▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓|
|40 ┼▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ [Grade A]
|   |▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓|
|35 ┼▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
|   |▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ [Grade D]
|30 ┼─────────────────────────────────────────────────────────
|   |
|25 ┼─────────────────────────────────────────────────────────
|   |
    Grade A     Grade B     Grade C     Grade D

5. Key Characteristics

Manufacturing Methods: Available as welded (ERW) or seamless (seamless rounds only)
Shapes Available: Round, square, rectangular, and custom shapes
Surface Finish: Typically has a smooth, uniform finish suitable for painting or galvanizing
Consistency: Cold-forming provides uniform mechanical properties and dimensional accuracy
Weldability: Excellent due to controlled carbon content
Cost-Effective: More economical than hot-rolled structural shapes for many applications

6. Common Applications

Building construction (columns, beams, trusses)
Bridge components and guard rails
Industrial structures (racks, frames, supports)
Agricultural equipment and implements
Architectural features (handrails, canopies, decorative elements)
Vehicle frames and roll cages
Transmission towers and electrical poles

7. Comparison with Similar Structural Materials

Property	ASTM A500 (Structural Tubing)	ASTM A36 (Structural Shapes)	ASTM A53 (Pipe)	ASTM A513 (Mechanical Tubing)
Primary Use	Structural frameworks	General structural	Pressure/mechanical	Precision mechanical parts
Shapes	Rounds, squares, rectangles	Wide-flange, channels, angles	Rounds only	Rounds, squares, rectangles
Surface Quality	Good, suitable for painting	Mill scale, requires cleaning	Black or galvanized	Excellent, smooth finish
Dimensional Tolerance	Good	Fair	Pipe schedule	Excellent, tight tolerances
Cost Factor	Medium	Low	Low to medium	High
Common Joining	Welding, bolting	Bolting, welding	Threading, welding	Machining, welding

8. Fabrication Considerations

Welding: Easy to weld with common processes (MIG, TIG, Stick)
Cutting: Can be cut with saws, band saws, or abrasive cutters
Bending: Cold bending possible with proper equipment and bending radii
Connection Methods: Can be welded, bolted, or use specialized structural connectors
Finishing: Accepts paint, powder coating, or hot-dip galvanizing well
Notching & Coping: Common for connections; avoid sharp corners to prevent stress concentrations

9. Section Properties Advantages

ASTM A500 tubing offers excellent structural efficiency:

High strength-to-weight ratio
Uniform stress distribution (no sharp corners)
Good torsional resistance (closed sections)
Aesthetic appearance for exposed applications
Efficient material use in compression (high radius of gyration)

10. Limitations and Special Considerations

Not for pressure applications (use A53, A106 for pressure)
Wall thickness limitations based on forming capabilities
Corner radii are larger than sharp corners of fabricated boxes
Heat-affected zones from welding may reduce strength locally
Quality varies between manufacturers; specify requirements clearly
Inspection requirements should be defined for critical applications

Note: ASTM A500 is produced to meet minimum mechanical properties. For design purposes, always consult the AISC (American Institute of Steel Construction) specifications for structural steel buildings and current building codes. Grade selection should consider load requirements, connection methods, and environmental conditions.

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