Note: In 2016, specifications A325 and A490 were officially withdrawn by ASTM and replaced by ASTM F3125.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.
*F1136, F2833 and F3019, as of 2020, have been withdrawn and combined into a new coating standard, F3393.
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
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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.