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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Note: In 2016, specifications A325 and A490 were officially withdrawn by ASTM and replaced by ASTM F3125.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. A summary of the now obsolete A325 specification remains 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: 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

F3125 Chemical Requirements

Heat Analysis 120ksi Type 1, % 150ksi Type 1, % 150ksi Type 3, %
Carbon 0.30 0.52 0.30 0.48 0.30 0.53
Manganese 0.60 min 0.60 min 0.60 min
Phosphorus 0.035 max 0.035 max 0.035
Sulfur 0.040 max 0.040 max 0.040
Silicon 0.15 0.30 -
Boron 0.003 max 0.003 max
Copper - - 0.20 0.60
Nickel - - 0.20* min
Chromium - - 0.45 min
Molybdenum - - 0.10* min
  • Additional footnotes and A325 type 3 chemistries not included here for brevity
  • 150ksi type 3- Either Nickel or Molybdenum must be present

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.