ASTM F3125-15

The ASTM F3125-15 specification consolidates and covers high strength structural bolts, both Hex Head & TC Bolts, that previously fell under A325, A490, F1852 & F2280. Bolts manufactured under this specification come in sizes from 1/2″ to 1-1/2″ inclusive. For bolts that do not fall under the diameter and length requirements for the above grades but have a similar mechanical values, see either ASTM Spec A354-BD or A449.

3.Ordering Information
NOTE 2—Bolts are sometimes detailed with names such as A325 HS, A325 SC, A325 X or A490 N. These names relate to connection design and bolt installation, but do not change the manufacturing requirements and are preferably not shown on bolt orders.

F3125-15 Classification

GradeMin StrengthTypeHead Style
A325120 ksi13Heax Head
F1852120 ksi13Twist-off (TC)
A490150 ksi13Hex Head
F2280150 ksi13Twist-off (TC)
Source: F3125-15

Heavy Hex Bolts may be ordered individually, packaged with nuts and washers or as assemblies and may be re lubricated in the field, using a stick wax or bee’s wax.

Tension Control Bolts are only shipped as an assembly of 1 bolt, 1 nut and 1 washer. TC Bolts MAY NOT BE RE LUBRICATED IN THE FIELD and may only be re lubricated by the manufacturer.

Table 1: Dimensions, Threads, Marking Matching Components

120 ksi Min Tensile150 ksi Min Tensile
Type 1Type 3Type 1Type 3
Hex Head Bolt Dimensions, ASME ᴮB18.2.6B18.2.6B18.2.6B18.2.6
Hex Head Bolt Thread Fit ASME ᴮB1.1 UNC 2AB1.1 UNC 2AB1.1 UNC 2AB1.1 UNC 2A
Hex Head Bolt Grade Marking ᴬᴰA325A325A490A490
Twist-Off Bolt Dimensions, ASME ᴮB18.2.6B18.2.6B18.2.6B18.2.6
Twist-Off Bolt Thread Fit ASME ᴮB1.1 UNC 2AB1.1 UNC 2AB1.1 UNC 2AB1.1 UNC 2A
Twist-Off Bolt Grade Marking ᴬᴰA325TCA325TCA490TCA490TC
Twist-Off Bolt Alt Marking ᴬᶜA325A325A490A490
Recommended Plain Nut A563 DHA563 DH3A563 DHA563 DH3
Recommended Alternative Nut DH3, D, C, C3C3
Recommended Coated Nut A563 DHA563 DH3A563 DHA563 DH3
Flat, Bevel or Thick WasherF436-1F436-3F436-1F436-3
Source: ASTM F3125-15

Table 2: Chemical Requirments

Heat Analysis120 ksi Min, Grade A325 & F1852150 ksi Min, Grade A490 & F2280
Type 1Type 3Type 1Type 3
Carbon or Alloy ᴰ with or without BoronComposition AComposition BBased on Corrosion Index ᴱAlloy ᴰ Steel with or without BoronBased On Corrosion Index ᴱ
Carbon0.30 - 0.520.33 - 0.400.38 - 0.480.3 - 0.52 max0.3 - 0.48 ᴬ0.3 - 0.53
Manganese0.60 min0.90 - 1.200.70 - 0.900.6 min0.6 min0.6 min
Phosphorus max0.0350.0350.0350.0350.0350.035
Sulfur max0.
Silicon0.15 - 0.300.15 - 0.300.3 - 0.5ʙʙʙ
Boron0.003 maxʙʙʙ0.003 maxʙ
Copperʙ0.25 - 0.450.2 - 0.40.2 - 0.60 ʙʙ0.2 - 0.6 ᴱ
Nickelʙ0.25 - 0.450.5 - 0.80.20 ʙ,c minʙ0.2 ᴱ,ᶠmin
Chromiumʙ0.45 - 0.650.5 - 0.750.45 ʙ minʙ0.45 ᴱ min
Molybdenumʙʙ0.063 max0.10 ʙ,c minʙ0.1 ᴱ,ᶠ min
Source ASTM F3125-15

Table 3: Number of Tests and Test Method or Criteria

Table 3 Number of Tests & Test Method or Criteria
All Grades, Types, StylesSample Size Per LotTest Method Notes
Tensile StrengthF1470F606/F606MWedge or Axial Full Size. Machined See 8.1.1
Proof LoadF1470F606/F606MMethod 1 or 2 optional. See 8.1.2
Dimensions and Thread FitASME B18.18ASME B18.2.6 B1.1 2A
Surface DiscontinuitiesF1470F788
Coating Weight/ThicknessF1470 ᴮProduct Specification
150 ksi grades all types/styles
Magnetic ParticalF1470F788Guide E709 of Practice E1444/E1444M
Carburization/DecarburizationAt least 1F2328
All Twist Off Assemblies
Fastener TensionF1470This Standard
Rotational Capacity ᴬF1470Annex A2
Source: ASTM F3125-15

Table 4: Tensile Strength Requirements for Bolts Tested Full Size

  120 ksi - A325 (Hex) & F1852 (Twist-Off)150 ksi - A490 (Hex) & F2280 (Twist-Off)
DiameterStress Area in ²Tensile min lbfProof Load min lbfProof Load min lbfTensile min lbfTensile max lbfProof Load min lbfProof Load min
Above values based on 120,000psi85,000psi92,000psi150,000psi173,000psi120,000psi130,000psi
Source: ASTM F3125-15

Table 5: Tensile Strength Requirements For Specimens Machined from Bolts

 Tensile minTensile maxYield minElongation in 4D minReduction of Area, min
120 ksi A325 & F1852120000 psiNA92,000 psi0.140.35
150 ksi A490 & F2280150000 psi173,000 psi130,000 psi0.140.4
Source: ASTM F3125-15

Table 6 Hardness Requirments for Bolts

  120 ksi Tensile, Grde A325 & F1852150 ksi Tensile, Grade A490 & F2280 
Brinell HBRockwell HRCBrinell HBRockwell HRC
≤ 1"Less than 2 x Diameter25331925343113523338
≤ 1"2 x Diameter and longer-319-34-352-38
Over 1"Less than 3 x Diameter25331925343113523338
Over 1"3 x Diameter and Longer-319-34-352-38
Source: ASTM F3125-15

F3125-15 Table 7 Twist-Off Style Assembly Installation Tension Test (Minimum Tension, lbf)

Source: ASTM F3125-15

ASTM F3125-15 approved Jan. 1st, 2015.


  • Contact Information

    Telephone: 215-537-8700
    FAX: 215-537-5569
    Postal address:
    1181 Unity Street Philadelphia, PA 19124
    Get Directions