Can I substitute Grade 5 or A449 bolts for F1554 grade 55 bolts?
In most circumstances the answer is no. For Grade 5 the answer is never. Although, Grade 5 meets the minimum yield requirements of F1554gr55, the minimum tensile requirements exceed the maximum tensile requirements in all cases.
A449 is similar in regards to meeting the minimum yield strength of F1554 Grade 55 across the board but is a little different in regards to tensile strengths due to there being different strength requirements for specific diameter ranges. Looking at the chart below, you can see that A449 runs into the same tensile problems as Grade 5 in diameters 1⁄4” – 11⁄2”. In diameters 15⁄8”-3”, the minimum tensile strength for A449 drops down to 90 ksi leaving a small window to comply with F1554 Grade 55 requirements. In addition to hitting the tensile perfectly, the elongation must also be well above its minimum of 14% and hit 21%.
|Grade||Marking||Size, inches||Tensile, ksi||Yield, ksi min||Elong. % min||RA % min||Meets|
|Grade 5||1⁄4 – 1||120||92||14||14||NO|
|F1554 Grade 55||1⁄2 - 2||75 - 95||55||21||30||-|
|21⁄4 - 21⁄2||75 - 95||55||21||22||-|
|23⁄4 - 3||75 - 95||55||21||20||-|
|31⁄4 - 4||75 - 95||55||21||18||-|
|A449||1⁄4 - 1||120||92||14||35||NO|
|11⁄8 - 11⁄2||105||81||14||35||NO|
|15⁄8 - 3||90*||58||14**||35||YES*|
|*Only if the tensile falls between 90-95ksi. **Elongation must meet or exceed 21%.|
If there is a supplemental weldabilty requirement (S-1) requested by the engineer; this is all null and void because both Grade 5 and A449 are heat treated to gain their strength properties. When heat is reapplied to a bolt that has been heat treated, it is probable that the physical properties (strength) of the bolt may be altered. See Welding High Strength Bolts for further information. Portland Bolt stocks from 1⁄2” through 31⁄4” diameter F1554 grade 55 round bar that complies to the S-1 supplemental requirement for weldability.
For The Grade 5, 105 > 75-95 ,and 81 > 55. Why not substitude Grade 5 for F1554 Grade 55 ?
@Kevin- There are several reasons why F1554g55 might be a more suitable material. First is cost. Apples to apples, F1554g55 is lower in cost. It is not a heat treated item and is made in much the same way as A36 or mild steel, so the cost to procure is typically much lower than a heat treated, medium carbon grade 5. Second is that F1554g55 is more ductile, which is advantageous in anchoring situations. Third is weldability. Most G55 material is weldable whereas grade 5 is not. If your application calls for any welding, F1554g55 will be a better option.