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ASTM A615
Rebar Tensile and Bend Testing 

ASTM A615 Bend Fixture for Concrete Rebar, Carbon Steel Bars
Universal Grip ASTM A615 bend fixture for universal testing machines

ASTM A615 - Deformed and Plain Carbon Steel Bars for Concrete
Reinforcement - PDF

ASTM A615 Bend Fixture – Universal Grip Data Sheet (PDF)

 

ASTM A615 is a specification for deformed and plain carbon-steel bars used in concrete reinforcement. In simple terms, it's the standard that tells manufacturers and engineers how steel rebar should be made and tested when it's used to reinforce concrete structures like buildings, bridges, and highways.

It mainly covers:

  • Grades of steel based on strength (Grades 40, 60, 75, 80 and 100).
     

  • Bar sizes and dimensions, from small to large diameters.
     

  • Requirements for chemical composition (what the steel is made of) and mechanical properties (like yield strength and elongation).
     

  • Guidelines for marking, testing, and certification to make sure the steel meets all necessary performance standards.
     

There are two types of bars in this standard:

  • Deformed bars, which have ridges or patterns to help grip the concrete.
     

  • Plain bars, which are smooth and used in specific structural situations.
     

This standard is widely used across the U.S. and globally, especially in structural and civil engineering projects.

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🔬 Lab Testing Requirements – ASTM A615

ASTM A615 requires that rebar (both deformed and plain bars) undergo several mechanical and chemical tests to ensure it meets the performance standards for structural applications.

 

1. 📏 Tensile Testing

Performed to determine yield strength, tensile strength, and elongation.

Equipment Needed:

Key Test Parameters:

Property

Requirement

Yield Strength

Minimum values based on grade (e.g., 60 ksi for Grade 60)

Tensile Strength

Must exceed yield strength (specific values per grade)

Elongation

Measured after fracture (usually in a 200 mm or 8 in. gage length)

Note: Yield point may be determined by:

  • The offset method (0.2% strain offset)
     

  • Extension under load method
     

 

2. 🧪 Bend Test

Tests ductility by bending the rebar around a mandrel.

Procedure:

  • A full-size bar is bent around a pin of a prescribed diameter, depending on the bar size and grade. Most sizes are bent 180°; #14 and #18 bars are bent 90°.
     

  • No cracking visible on the tension (outer) surface = Pass.
     

Mandrel Diameter (as a factor of bar diameter):

Pin diameters for Grade 60 bars (d = nominal bar diameter):

  • #3, #4, #5: 3½d, bent 180°

  • #6, #7, #8: 5d, bent 180°

  • #9, #10, #11: 7d, bent 180°

  • #14 and #18: 9d, bent 90°

Other grades use the pin diameters and bend angles in the bend test table of the current edition of A615. Grade 40 is only made in sizes #3 to #6.

 

3. ⚗️ Chemical Composition Testing

Ensures the steel composition falls within limits for elements like C, Mn, P, S, etc.

Common Techniques:

  • Optical Emission Spectroscopy (OES)
     

  • Inductively Coupled Plasma (ICP)
     

  • Wet chemistry methods
     

Important Limits:

  • A615 sets no limit on carbon, manganese or sulfur; they are reported on the mill certificate
     

  • Phosphorus is limited to 0.06% maximum
     

Note: The chemical composition is especially critical if the steel is dual-certified to ASTM A615 and A706 (weldability concerns).

 

4. 📄 Sampling and Retesting Criteria

  • Bars must be tested by heat number (each batch of molten steel).
     

  • One tension test and one bend test from the largest bar size rolled in each heat.
     

  • If a test fails, retests are allowed under certain conditions.
     

 

Optional or Supplementary Tests

Some projects may require:

  • Charpy impact tests (for seismic or cold regions—if dual certified with A706)
     

  • Hardness testing (as a quick QC check)
     

 

🧾 Reporting Requirements

A typical test report should include:

  • Grade and size of bar
     

  • Heat number
     

  • Results of tensile and bend tests
     

  • Chemical composition
     

  • Lab accreditation/certification details (e.g., ISO 17025)

ASTM A615 FAQ

What pin diameter is used for an ASTM A615 #5 Grade 60 bend test?

3½ times the nominal bar diameter, about 55 mm (2.2 in) for a #5 bar, bent 180° with no cracking on the outside of the bend.

What gauge length is used for rebar elongation?

Elongation is measured over an 8 in (200 mm) gauge length on the full-size bar.

How many tests does A615 require?

One tension test and one bend test from the largest bar size rolled in each heat.

What is the difference between A615 and A706?

A615 covers general carbon-steel rebar and limits only phosphorus in the chemistry. A706 is low-alloy, weldable rebar with limits on carbon, manganese and other elements, plus tighter tensile-to-yield requirements for seismic use.

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