ASTM F3125

Note: In 2016, specifications A325 and A490 were officially withdrawn by ASTM and replaced by ASTM F3125. A325 and A490 heavy hex structural bolts are now grades under the new F3125 specification. Summaries of the now obsolete A325 and A490 specifications remain on our site for reference purposes only.

This specification covers the chemical, physical and mechanical requirements for structural bolts manufactured from steel and alloy steel, in two strength grades, two styles and two types. This specification is a consolidation of and replacement for six ASTM standards ranging from 1/2″ through 1-1/2″ diameter:  A325, A325M, A490, A490M, F1852 and F2280. The main difference between this standard and the older, existing standards is that A325s from 1-1/8” to 1-1/2” now have the same mechanical requirements as A325s 1” and under. Previously the larger bolts had slightly lower requirements.

F3125 Bolt Types

Grade Min Strength, Tensile Type Style
A325 120ksi min 1 or 3 Heavy Hex Head
A325M 830MPa min 1 or 3 Heavy Hex Head
F1852 120ksi min 1 or 3 Twist-Off/TC
A490 150-173ksi 1 or 3 Heavy Hex Head
A490M 1040MPa 1 or 3 Heavy Hex Head
F2280 150ksi 1 or 3 Twist-Off/TC
  • Type 1 – 120ksi - carbon, carbon boron, alloy, or alloy boron steel
  • Type 1 – 150ksi – alloy or alloy boron steel
  • Type 3 – weathering Steel

Chemical Requirements – Type 1

Heat Analysis 120ksi, % 150ksi, %
Carbon 0.30 – 0.52 0.30 – 0.48*
Manganese 0.60 min 0.60 min
Phosphorus 0.035 max 0.035 max
Sulfur 0.040 max 0.040 max
Silicon 0.15 – 0.30 -
Boron 0.003 max 0.003 max
Copper - -
Nickel - -
Chromium - -
Molybdenum - -
*Carbon 0.35-0.53% for 1-1/2” A490/150ksi bolts

Chemical Requirements – Type 3

Heat Analysis 120ksi, % Comp A 120ksi, % Comp B 120ksi, % Index 150ksi, % Index
Carbon 0.33 – 0.40 0.38 – 0.48 0.30 – 0.52 0.30 – 0.53
Manganese 0.90 – 1.20 0.70 – 0.90 0.60 min 0.60 min
Phosphorus 0.035 max 0.035 max 0.035 max 0.035 max
Sulfur 0.040 max 0.040 max 0.040 max 0.040 max
Silicon 0.15 – 0.30 0.30 – 0.50    
Copper 0.25 – 0.45 0.20 – 0.40 0.20 – 0.60 0.20 – 0.60
Nickel 0.25 – 0.45 0.50 – 0.80 0.20 min* 0.20 min*
Chromium 0.45 – 0.65 0.50 – 0.80 0.20 min 0.20 min
Molybdenum   0.06 max 0.10 min* 0.10 min*
*Either Nickel or Molybdenum must be present in the amount specified *Corrosion Index based on ASTM Guide G101

F3125 Mechanical Properties

Grade Tensile, ksi Yield, ksi min Elongation, % min RA, % min
120ksi (A325/F1852) 120 min 92 14 35
150ksi (A490/F2280) 150-173 130 14 40

F3125 Marking Requirements & Matching Components

120ksi, Type 1 120ksi, Type 3 150ksi, Type 1 150ksi, Type 3
Marking A325 A325 A490 A490
Nut, Plain A563 DH A563 DH3 A563 DH A563 DH3
Nut, Coated A563 DH A563 DH3 A563 DH A563 DH3
Washer F436-1 F436-3 F436-1 F436-3
  • A194 2H nuts are an acceptable substitute for A563 DH nuts
  • Suitable plain finish nut alternatives can be found in the full F3125 text
  • Supplementary requirements S1 and S2 have special marking requirements.

F3125 Permitted Coatings

Bolt F2329 Hot Dip Galvanizing B695 Mechanical Galvanizing F1136 Zinc/Aluminum (Geomet) F2833 Zinc/Aluminum
A325 Approved Class 55 Grade 3 Grade 1
F1852 Not Approved Class 55 Not Approved Not Approved
A490 Not Approved Not Approved Grade 3 Grade 1
F2280 Not Approved Not Approved Not Approved Not Approved
*Other coatings may be used on 120ksi/A325 fasteners upon agreement between purchaser and user. Coatings on 150ksi/A490 fasteners must be qualified by ASTM committee F16.

F3125 Nut Overtap Allowances

Size F2329 and B695, in F1136 and F2833, in
½-13 0.018 0.009
5/8-11 0.020 0.010
¾-10 0.020 0.010
7/8-9 0.022 0.011
1-8 0.024 0.012
1-1/8-7 0.024 0.012
1-1/4-7 0.024 0.012
1-3/8-6 0.027 0.014
1-1/2-6 0.027 0.014
  • Hot dip galvanized nuts are tapped after coating. Other coatings are applied after nut tapping
  • Nuts overtapped for use with 150ksi/A490 bolts shall be proof load tested to 175ksi minimum after overtapping

F3125 Supplemental Requirements

S1 A325/120ksi bolts up to 4x the diameter threaded full length. Mark A325T
S2 Alternate head geometry or thread length. Mark A325S or A490S
S3 Lubricants
S4 Rotational Capacity Testing