ASTM A706 covers deformed and plain low alloy steel bars for concrete reinforcement with restrictive mechanical properties and chemical composition in order to enhance weldability. This specification covers bars and coils in two grades, Grade 60 and Grade 80. The grade designates the yield strength of the material, i.e. Grade 60 has a 60ksi minimum yield.
A706 Designation Numbers
| Bar No. | Nominal Diameter |
|---|---|
| 3 | 0.375” |
| 4 | 0.500” |
| 5 | 0.625” |
| 6 | 0.750” |
| 7 | 0.875” |
| 8 | 1.000” |
| 9 | 1.128” |
| 10 | 1.270” |
| 11 | 1.410” |
| 14 | 1.693” |
| 18 | 2.257” |
A706 Mechanical Requirements
| Grade 60 | Grade 80 | |
|---|---|---|
| Tensile, ksi | 80 | 100 |
| Yield, ksi | 60-78 | 80-98 |
| Elongation in 8” | ||
| Bar size #3,4,5,6 | 14 | 12 |
| 7,8,9,10,11 | 12 | 12 |
| 14,18 | 10 | 10 |
| *Tensile strength shall not be less than 1.25 times the actual yield strength | ||
A706 Chemical Requirements
| Element | Max % |
|---|---|
| Carbon | 0.30 |
| Manganese | 1.50 |
| Phosphorous | 0.035 |
| Sulfur | 0.045 |
| Silicon | 0.50 |
A706 Bend Test Requirements
| Bar Designation# | Pin Dia, Grade 60 | Pin Dia, Grade 80 |
|---|---|---|
| 3,4,5 | 3d | 3-1/2d |
| 6,7,8 | 4d | 5d |
| 9,10,11 | 6d | 7d |
| 14,18 | 8d | 9d |
Weldability
In addition to the above chemical requirements, A706 rebar must also have a carbon equivalent (CE) not exceeding 0.55%. The way to calculate this is to plug the chemical composition figures for a given heat lot of steel into the following formula:
CE = %C + (%Mn / 6) + (%Cu / 40) + (%Ni / 20) + (%Cr / 10) – (%Mo / 50) – (%V / 10)
Rebar produced to this specification shall be marked with the letter “W” to indicate weldability.