Structural Carbon Steel Hex Bolt ASTM F3125 / F3125M

Place of Origin CHINA
Brand Name QBH
Certification ISO9001
Model Number 1/2 to 1-1/2
Minimum Order Quantity 900kg
Price Negotiation
Packaging Details 25kg Carton+900kg/Pallet
Delivery Time 30days
Payment Terms L/C, T/T,OA
Supply Ability 500TON/MONTH

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Product Details
Material Carbon Steel Size 1/2 To 1-1/2
Surface Treatment Plain,Zinc,Black,H.D.G Grade A325, F1852, A490, F2280
Process Cold Forging,Hot Forging Sample Free Sample
Packaging 25kg Carton+900kg/Pallet Head Type Heavy Hex Head
Application Industry,structural Buliding Length 10mm-800mm
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ASTM F3125 Steel Hex Bolt


Structural Steel Hex Bolt


ASTM F3125M Steel Hex Bolt

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Product Description

ASTM F3125/F3125M is a structural bolt specification covering inch and metric bolt grades. This specification contains 4 inch series bolting grades: A325, F1852, A490, and F2280. These will be addressed in this article. When looking at the mechanical requirements of bolts it appears that a grade A325 and SAE J429 Grade 5 are identical as do the grade A490 and the SAE J429 Grade 8.


This begs the question, "Can an SAE J429 Grade 5 be used when an ASTM F3125 grade A325 is specified?" The answer is definitely no. This is also the case for substituting a Grade 8 when grade A490 is specified, and here are some reasons why:

First, grade A325 and A490 bolts are produced with a heavy hex head configuration which provides a wider bearing surface over which to distribute the load. Grade 5 and 8 bolts are produced to standard hex cap screw configuration and therefore cannot distribute the load as much as is needed for structural applications.

Second, the shank length (non-threaded portion of the body) on the grade A325 and A490 bolts is designed to be greater (shorter thread lengths) than your standard hex bolt or hex cap screw. Remember, the weakest section of standard carbon steel fasteners is through the threaded region. Minute design changes such as this can create a stronger tensile connection.

Third, the difference in thread length is also likely to result in a change in shear strength. The following two diagrams demonstrate this difference:




Structural Carbon Steel Hex Bolt ASTM F3125 / F3125M 0

Screw Thread
1/2 5/8 3/4 7/8 1 1-1/8 1-1/4 1-3/8 1-1/2
ds max
s Nominal Size
e max
k Nominal Size
b Ref.
0.515 0.642 0.768 0.895 1.022 1.149 1.277 1.404 1.531
0.482 0.605 0.729 0.852 0.976 1.098 1.223 1.345 1.47
7/8 1-1/16 1-1/4 1-7/16 1-5/8 1-13/16 2 2-3/16 2-3/8
0.875 1.062 1.25 1.438 1.625 1.812 2 2.188 2.375
0.85 1.031 1.212 1.394 1.575 1.756 1.938 2.119 2.3
1.01 1.227 1.443 1.66 1.876 2.093 2.309 2.526 2.742
0.969 1.175 1.383 1.589 1.796 2.002 2.209 2.416 2.622
5/16 25/64 15/32 35/64 39/64 11/16 25/32 27/32 15/16
0.323 0.403 0.483 0.563 0.627 0.718 0.813 0.878 0.974
0.302 0.378 0.455 0.531 0.591 0.658 0.749 0.81 0.902
1 1.25 1.38 1.5 1.75 2 2 2.25 2.25




Note: In 2016, ASTM A325 was officially withdrawn and replaced by ASTM F3125, in which A325 now becomes a grade under the F3125 specification. The F3125 specification is a consolidation and replacement of six ASTM standards, including; A325, A325M, A490, A490M, F1852, and F2280. We are choosing to keep this technical information about the now obsolete A325 specification on our website for reference and informational purposes only.




Prior to its withdrawl in 2016, the ASTM A325 specification covered high strength heavy hex structural bolts from 1/2″ diameter through 1-1/2″ diameter. These bolts are intended for use in structural connections and therefore have shorter thread lengths than standard hex bolts. Refer to the Structural Bolts page of our site for thread lengths and other related dimensions.

This specification is applicable to heavy hex structural bolts only. For bolts of other configurations and thread lengths with similar mechanical properties, see Specification A449.

Bolts for general applications, including anchor bolts, are covered by Specification A449. Also refer to Specification A449 for quenched and tempered steel bolts and studs with diameters greater than 1-1/2″ but with similar mechanical properties.



Mechanical Properties of ASTM F3125/F3125M Grades A325 & A490 Structural Bolts with Nut Compatibility

Mechanical Properties of ASTM F3125/F3125M Grades A325 & A490 Structural Bolts with Nut Compatibility



Grade A325 bolts are available in diameters from 1/2 to 1-1/2 inch (for diameters greater than 1-1/2, ASTM A449 specifications should be considered) with a minimum tensile strength of 120,000 PSI. They also come in two types. Type 1 is a medium carbon steel and can be galvanized; Type 3 is a weathering steel that offers atmospheric corrosion resistance similar to that of ASTM A242 or A588 steels. Type 3 grade A325 bolts shall be marked "A325" to distinguish them from standard grade A325s.

Grade A490 bolts are available in diameters from 1/2 to 1-1/2 inch diameters with a minimum tensile strength of 150,000 PSI for all diameters, and are offered in two types. Type 1 is alloy steel, and Type 3 is weathering steel that offers atmospheric corrosion resistance similar to that of ASTM A242 or A588 steels. Type 3 grade A490 bolts shall be marked "A490".

ASTM A490 bolts should not be galvanized or electroplated. The problem with hot dip galvanizing is that the molten bath of zinc exceeds the fastener's tempering temperature and would cause the fastener to anneal in the bath. In addition, a major problem with hot dip galvanizing and electroplating grade A490 bolts is the potential for hydrogen embrittlement. This scenario may occur when atomic hydrogen is introduced during the pickling process that takes place prior the plating or hot dip galvanizing process.




Process flow


Cold forging

Annealing treatment(if need) ➨ wiredrawing ➨ clod forging ➨ thread rolling ➨make heat treatmentFinish Packing


Hot forging

Cutting material hot forging turning shrink diameter(half thread)thread rolling make heat treatmentFinish Packing





Materials and Chemical compstition




C Si Mn P S Cr Ni Cu
0.34 0.13 0.73 0.012 0.002 0.02 0.01 0.02






C Si Mn P S Cr Ni Cu
0.45 0.23 0.58 0.014 0.006 0.057 0.008 0.016




C Si Mn P S Cr Ni Cu
0.4 0.21 0.54 0.015 0.008 0.95 0.02 0.02
















Packing in small boxes according to customer’s requirements

Packing in plastic bag according to customer’s requirements




EURO Pallet







In brief Type 3 grade A325 bolts shall be marked “A325” to distinguish them from standard grade A325s. Likewise Grade A490 bolts are available in diameters from 1/2 to 1-1/2 inch diameters with a minimum tensile strength of 150,000 PSI for all diameters, and are offered in two types.

In Fact ASTM A325 is an ASTM International standard for heavy hex structural bolts, titled Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength. It defines mechanical properties for bolts that range from 12 to 1 12 inches (13 to 38 mm) in diameter.

In accordance with ASTM A325, all threaded components of the fastener assembly must be galvanized by the same process and the supplier’s option is limited to one process per item with no mixed processes in a lot.



This Specification deals principally with two strength grades of high-strength
bolts, ASTM A325 and A490, and with their design, installation and inspection in
structural steel joints. Equivalent fasteners, however, such as ASTM F1852
(equivalent to ASTM A325) twist-off-type tension-control bolt assemblies, are
also covered. These provisions may not be relied upon for high-strength fasteners
of other chemical composition, mechanical properties, or size. These provisions do
not apply when material other than steel is included in the grip; nor are they
applicable to anchor rods.
This Specification relates only to the performance of fasteners in structural
steel joints and those few aspects of the connected material that affect this
performance. Many other aspects of connection design and fabrication are of equal
importance and must not be overlooked. For more general information on design
and issues relating to high-strength bolting and the connected material, refer to
current steel design textbooks and the Guide to Design Criteria for Bolted and
Riveted Joints, 2 nd Edition (Kulak et al., 1987).




The advantages of QBH

  • QBH brand sales to the main quality assurance.
  • Years of export trade management, excellent service, word-of-mouth guarantee.
  • By working with TUV,escort for quality.
  • Customization of non-standard parts can be made according to customer's requirements and drawings.
  • For quality customers,we can provide a certain credit period.




1. How do you let me trust you.
Jiaxing City Qunbang Hardware Co.,ltd hs its own right of import and export,QBH trademark in China,United States,European Union have been registered.At the same time,you can also check the registration information of our company in the China industry and Commerce system.
2. How about your price.
We will be based on different markets,for different quality and quantity,tailor-made prices for customers,in order to achieve win-win goal.
3. How do you control your quality.
Incoming quality contral( IQC)→Process Quality control(PQC)→Output quality control(OQC),and the random samples is sent to TUV for testing.If the customer received the goods and found quality problems,QBH company promises to be responsible for returning money or replenishing the goods
4. Could you provide free samples?
For new customer, We can provide free samples for standard fastener, But the clients will pay the express
charges. For old customer, We will send you free samples and pay express charges by ourself.
5. Do you accept small order?
QBH company can accept small orders if we have them in stock.Generally speaking,the stock probability of stainless steel fasteners is higher than that of carbon steel fasteners.
6. How about your delivery time
What we pursure is the high efficiency movement pattern,the stainless steel fastener delivery time about 15days,the carbon steel fastener will it about 30days
7. What is your packing.
Usually 25KG/carbon,36CTNS on the pallets,or 20-30kg/Bags,then on the pallet,QBH company personalized packagingis also available,like 10PCS/plastic bag or 10pcs/box,it can print some information
such as LOGO and pattern of customers.
8. What is your payment term
Normally,our terms of payment are TT and L/C,if we cooperate for a long time,we can reach the point of mutual trust,and fully support our customers to become bigger and stronger in the local market.
Not only in the price concessions,but also in the payment can also be made on credit,Specific credit sales time needs to be negotiated separately