F1554 Grade 55


ASTM F1554 grade 55 anchor bolts are manufactured from a modified mild steel that has a higher minimum yield strength (55 ksi) than traditional A36 mild steel (36 ksi). This specification was widely used in the light pole and traffic signal industry long before the ASTM F1554 specification was introduced in 1994 and was commonly referred to as A36M55. Just as with grade 36, grade 55 covers anchor bolts in diameters ranging from 1/2″ through 4″.


F1554 grade 55 anchor bolts can be provided in either a black or galvanized condition.


Contrary to popular belief, not all grade 55 material is weldable. If weldability is required, supplementary requirement S1 must be specified. A weldable grade 55 may be substituted at the supplier’s option when grade 36 is specified. All of the grade 55 round bar that Portland Bolt stocks will meet the S1 weldability requirements.

Supplementary Testing

Charpy impact testing can be requested as a supplementary requirement. Supplemental S4 designates impact testing at +40°F and is applicable to both grades 55 and 105. Supplemental S5 designates impact testing at -20°F and is applicable only to grade 105. In both cases the minimum v-notch energy requirement is an average of 15ft-lbs for three specimens, with no one specimen falling below 12ft-lbs.

Material Substitution

Be skeptical of fastener distributors and manufacturers with limited manufacturing capabilities who attempt to substitute 1045 round bar or even A193 grade B7 material for F1554 grade 55. These materials and other grades of steel may exceed the tensile and yield requirements of the F1554 grade 55 specification, but will usually not meet the elongation and reduction of area requirements. Grade 55 round bar is not commonly available through local warehouses. Portland Bolt buys mill runs of round bar and stocks this material for immediate processing.

Mechanical Requirements

Grade Identification1 Size, Inches Tensile, ksi Yield, ksi min Yield, MPa min Elong. % min Reduction of Area %, min
55 ASTM F1554 Grade 55 1/4 – 2 75 – 95 55 380 21 30
2-1/4 – 2-1/2 75 – 95 55 380 21 22
2-3/4 – 3 75 – 95 55 380 21 20
3-1/4 – 4 75 – 95 55 380 21 18
1Color coding (yellow) is required while permanent stamping with manufacturer’s identification and grade designation are supplementary requirements.

Nuts and Washers

Grade Identification Size, Inches Recommended A563 Nut Washer
Plain Finish Hot-Dip or Mechanical Zinc Coated
Grade Style Grade Style
55 ASTM F1554 Grade 55 1/2 – 1-1/2 A Hex A Heavy Hex F436
1-5/8 – 4 A Heavy Hex A Heavy Hex
For additional compatible nuts see the Nut Compatibility Chart.