1. The Same Section Under Two Names
Angle steel and angle iron are two names for the same product: a hot rolled steel section with an L shaped cross section. The term angle iron dates from the early days of the steel industry when such sections were made from wrought iron, and the name stayed in common use long after production switched to steel. Today every angle iron on the market is made of steel, so the two terms can be used interchangeably in the steel trade.
2. Material Facts
Modern angle iron is not iron at all in the metallurgical sense; it is a low carbon steel with a carbon content of about 0.20 percent or less. The steel is produced in grades such as Q235, A36 and S275JR, with yield strengths between 235 and 275 MPa and tensile strengths around 370 to 550 MPa. Cast iron and wrought iron, the historical materials, are no longer used for structural angles because steel offers better strength, ductility and weldability.
3. How the Section Is Made
Angle sections are produced by hot rolling: a reheated steel bloom passes through shaped rolls that gradually form the L profile in a series of passes. The process gives the section a scale-covered surface, rounded corners on the inside and a controlled cross section that follows the shape table of the standard. Cold formed angles, made by bending steel strip, are also available but are a different product with thinner walls and tighter tolerances.
4. Manufacturing Standards
The dimensions and tolerances of hot rolled angles are defined by standards such as GB/T 706 in China, ASTM A6 in North America and EN 10056 in Europe. The standards state the leg sizes, thicknesses, corner radii and unit weights, and they also define the permitted deviations for length, straightness and section dimensions. When ordering, the standard should be named together with the grade so that the supplier delivers the correct profile.
5. How to Specify an Angle Correctly
To avoid confusion, an angle order should state the product as angle steel or angle iron, the leg sizes, the thickness, the grade, the standard and the length. For example, equal angle 50x50x5 in Q235B to GB/T 706 in 6 m lengths leaves no room for ambiguity. Specifying in this way ensures that the delivered section, its mechanical properties and its certificate all match the design assumption.
Frequently Asked Questions
Q: Is angle iron actually made of iron? No, angle iron is made of low carbon steel; the name is historical and dates from the time when similar sections were made from wrought iron.
Q: Which term should be used in an order? Both terms are understood, but it is safer to write angle steel in technical documents and to add the grade, size and standard to make the order unambiguous.
Q: Is there any strength difference between angle steel and angle iron? No, they are the same product, and the strength is determined by the steel grade, not by the name used.
Q: How are angle sections manufactured? Standard angles are produced by hot rolling the section in a series of shaped roll passes, and thin walled angles can also be cold formed from steel strip.
Q: What information should an angle order contain? The order should state the leg sizes, thickness, steel grade, manufacturing standard, length and quantity, together with any surface treatment such as galvanizing.