ASTM A325

Last updated

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. [1]

Contents

The equivalent metric standard is ASTM A325M, which is titled Standard Specification for Structural Bolts, Steel, Heat Treated 830 MPa Minimum Tensile Strength. It defines mechanical properties for sizes M12–36. [2]

This is a standard set by the standards organization ASTM International, a voluntary standards development organizations that sets technical standards for materials, products, systems, and services.

In 2016, ASTM officially withdrew specification A325 and replaced it with ASTM F3125. [3] To minimize confusion, bolt head markings are unchanged and the designation A325 is retained as a grade name within the new standard. [4] In 1951, A325 bolts were recognized as equivalent to a hot driven ASTM A141 rivet. [5]

Types

The type refers to the type of material used to make the bolt. The standard currently defines two types, however it previously defined the following three: [6]

There is also a T version, which is used to refer to fully threaded bolts. [6]

Note that independent of the material the bolt is quenched and tempered. [7]

Connection types

There are also three connection types defined: [6]

Mechanical properties

Mechanical properties, imperial

These types of bolts are designed to be tightened to near their proof strength, in order to create significant bolt tension. The standard states that the bolts must be tightened to at least 70% of the tensile yield strength. These bolts use the same material as their common cousins (ASTM F568M for metric bolts), but have a thicker and wider head to more effectively distribute the load. This modified geometry is often referred to as heavy hex geometry. [8] Nuts must meet ASTM A563, which also uses heavy hex geometry. [9] Dimensions of heavy hex geometry are per document ANSI/ASME B18.2.6, which uses "coarse" threads as defined by Unified Thread Standard.

ASTM 325 bolts can be considered equivalent to Grade 8.8 bolts according to ASTM F568M.[ citation needed ]

For a higher strength version of this type of bolt, see ASTM A490.

Head markings and mechanical properties for imperial sizes [7]
Head markingGradeNominal size range

[in]

Proof strength

[ksi]

Yield strength (min)

[ksi]

Tensile strength (min)

[ksi]

Core hardness

[Rockwell] [10]

Hex cap screw-ASTM A325.svg
or [10]
Hex cap screw-ASTM A325 lines.svg
Type 112–1 (inc.)8592120C24–35
1–1+127481105C19–31
Hex cap screw-ASTM A325 type 2.svg Type 212–18592120C24–35
Hex cap screw-ASTM A325 type 3.svg [11] Type 312–18592120C24–35
1–1+127481105C19–31

Mechanical properties, metric

Head markings and mechanical properties for metric sizes [8]
Head markingGradeNominal size range

[mm]

Proof strength

[MPa]

Yield strength (min)

[MPa]

Tensile strength (min)

[MPa]

Core hardness

[Rockwell]

Hex cap screw-ASTM A325M 8S.svg Type 112–36 [2] 600660830C23–34
Hex cap screw-ASTM A325M type 2.svg Type 2
Hex cap screw-ASTM A325M 8S3.svg Type 3

/mm

See also

Related Research Articles

<span class="mw-page-title-main">Rebar</span> Steel reinforcement

Rebar, known when massed as reinforcing steel or steel reinforcement, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has low tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface features a continuous series of ribs, lugs or indentations to promote a better bond with the concrete and reduce the risk of slippage.

<span class="mw-page-title-main">Rivet</span> Permanent mechanical fastener

A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the tail. On installation, the deformed end is called the shop head or buck-tail.

<span class="mw-page-title-main">Fastener</span> Hardware device that mechanically joins or affixes two or more objects together

A fastener or fastening is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or dismantled without damaging the joining components. Steel fasteners are usually made of stainless steel, carbon steel, or alloy steel.

<span class="mw-page-title-main">Bolted joint</span> Mechanical joint secured by a threaded fastener

A bolted joint is one of the most common elements in construction and machine design. It consists of a male threaded fastener that captures and joins other parts, secured with a matching female screw thread. There are two main types of bolted joint designs: tension joints and shear joints.

<span class="mw-page-title-main">Structural steel</span> Type of steel used in construction

Structural steel is a category of steel used for making construction materials in a variety of shapes. Many structural steel shapes take the form of an elongated beam having a profile of a specific cross section. Structural steel shapes, sizes, chemical composition, mechanical properties such as strengths, storage practices, etc., are regulated by standards in most industrialized countries.

<span class="mw-page-title-main">SAE steel grades</span> Standard alloy numbering system for steel grades

The SAE steel grades system is a standard alloy numbering system for steel grades maintained by SAE International.

<span class="mw-page-title-main">Anchor bolt</span> Connection elements that transfer loads and shear forces to concrete.

Anchor bolts are used to connect structural and non-structural elements to concrete. The connection can be made by a variety of different components: anchor bolts, steel plates, or stiffeners. Anchor bolts transfer different types of load: tension forces and shear forces.

<span class="mw-page-title-main">Shear force</span> Coplanar forces acting on the same body in opposite directions

In solid mechanics, shearing forces are unaligned forces acting on one part of a body in a specific direction, and another part of the body in the opposite direction. When the forces are collinear, they are called tension forces or compression forces. Shear force can also be defined in terms of planes: "If a plane is passed through a body, a force acting along this plane is called a shear force or shearing force."

<span class="mw-page-title-main">Screw</span> Type of fastener characterized by a thread wrapped around a cylinder core

A screw is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to the head. The most common uses of screws are to hold objects together and there are many forms for a variety of materials. Screws might be inserted into holes in assembled parts or a screw may form its own thread.

<span class="mw-page-title-main">Nut (hardware)</span> Type of fastener with a threaded hole

A nut is a type of fastener with a threaded hole. Nuts are almost always used in conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads' friction, a slight stretching of the bolt, and compression of the parts to be held together.

ASTM A992 steel is a structural steel alloy often used in the US for steel wide-flange and I beams. Like other carbon steels, the density of ASTM A992 steel is approximately 7850 kg/m3. ASTM A992 steel has the following minimum mechanical properties, according to ASTM specification A992/A992M. Tensile yield strength, 345 MPa (50 ksi); tensile ultimate strength, 450 MPa (65 ksi); strain to rupture in a 200-mm-long test specimen, 18%; strain to rupture in a 50-mm-long test specimen, 21%.

ISO 898 is an international standard that defines mechanical and physical properties for metric fasteners. This standard is the origin for other standards that define properties for similar metric fasteners, such as SAE J1199 and ASTM F568M. It is divided into five (nonconsecutive) parts:

ASTM F568M is an ASTM International standard for metric bolts, screws and studs that are used in general engineering applications. It is titled: Standard Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners. It defines mechanical properties for fasteners that range from M1.6 to 100 in diameter. The standard was withdrawn in 2012. and has been replaced by ISO 898-1

ASTM A354 is an ASTM International standard that defines chemical and mechanical properties for alloy steel bolts, screws, studs, and other externally threaded fasteners. It is officially titled: Standard Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners.

ASTM A490 and ASTM A490M are ASTM International standards for heavy hex structural bolts made from alloy steel. The imperial standard is officially titled Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength, while the metric standard (M) is titled Standard Specification for High-Strength Steel Bolts, Classes 10.9 and 10.9.3, for Structural Steel Joints.

<span class="mw-page-title-main">Threaded rod</span> Rod with ridges wrapped around it

A threaded rod, also known as a stud, is a relatively long rod that is threaded on both ends; the thread may extend along the complete length of the rod. They are designed to be used in tension. Threaded rod in bar stock form is often called all-thread (ATR); other names include fully-threaded rod, redi-rod, continuously-threaded rod, and TFL rod.

<span class="mw-page-title-main">Bolt (fastener)</span> Threaded fastener with an external male thread requiring a matching female thread

A bolt is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to a matching nut. The bolt has an external male thread requiring a matching nut with a pre-formed female thread.

<span class="mw-page-title-main">Direct tension indicator</span> Mechanical Load Cells

Direct tension indicators, or DTIs, are single-use mechanical load cells used to indicate when the required tension has been achieved in structural fastener assemblies.

Adhesive bonding is a process by which two members of equal or dissimilar composition are joined. It is used in place of, or to complement other joining methods such mechanical fasting by the use nails, rivets, screws or bolts and many welding processes. The use of adhesives provides many advantages over welding and mechanical fastening in steel construction; however, many challenges still exist that have made the use of adhesives in structural steel components very limited.

The Research Council on Structural Connections (RCSC) is a research organization focused on bolted structural connections. Their technical standard on this subject is cited in the US steel design code.

References

  1. ASTM A325 - 09 , retrieved 2009-06-13.
  2. 1 2 ASTM A325M - 09 , retrieved 2009-06-13.
  3. "A325 Structural Bolts". Portland Bolt. Retrieved 2019-01-18.
  4. Shaw, Robert E. Jr. (Nov 2015). "New Twists and Turns". STRUCTURE Magazine.
  5. Research Council on Structural Connections (Jan 1951), Specifications for Assembly of Structural Joints Using High Tensile Steel Bolts, American Institute of Steel Construction
  6. 1 2 3 "ASTM A325 - Portland Bolt" . Retrieved 2009-06-13..
  7. 1 2 3 ASTM, SAE and ISO grade markings and mechanical properties for steel fasteners , retrieved 2009-06-06.
  8. 1 2 "Metric structural fasteners". University of Iowa. Archived from the original on 1999-04-21. Retrieved 2009-06-06..
  9. Kulak, Geoffrey L. (2001). Guide to Design Criteria for Bolted and Riveted Joints (PDF) (2nd ed.). American Institute of Steel Construction. p. 37. ISBN   978-1564240750.
  10. 1 2 Grade Markings: Carbon Steel Bolts , retrieved 2009-05-30.
  11. Other markings may be used to denote atmospheric corrosion resistant material