ASTM A490 and ASTM A490M are

ASTM International ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...

standards for heavy hex structural bolts made from

alloy steel Alloy steel is steel that is Alloy, alloyed with a variety of elements in amounts between 1.0% and 50% by weight, typically to improve its List of materials properties#Mechanical properties, mechanical properties. Types Alloy steels divide into ...

. The imperial standard is officially titled ''Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength'', while the

metric Metric or metrical may refer to: Measuring * Metric system, an internationally adopted decimal system of measurement * An adjective indicating relation to measurement in general, or a noun describing a specific type of measurement Mathematics ...

standard (M) is titled ''Standard Specification for High-Strength Steel Bolts, Classes 10.9 and 10.9.3, for Structural Steel Joints''... In 2016, specifications A325 and A490 were officially withdrawn by ASTM and replaced by ASTM F3125.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.

Connection types

There are also three connection types defined:. *SC: A slip critical connection. *N: A bearing type connection where the threads are on the shear plane. *X: A bearing type connection where the threads are not on the shear plane.

Mechanical properties

These bolts are equivalent to

ASTM A325 ASTM A325 is an ASTM International standard for heavy hex structural Bolt (fastener), bolts, titled ''Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength''. It defines mechanical properties for bol ...

bolts in application and geometry, but are made to a higher strength. The imperial grades are made to the same strength specifications as ASTM A354 grade BD. The metric grades are made to the same strength specifications as

ASTM F568M 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 ...

property class 10.9. Also, unlike their weaker counterparts they may not be coated by

hot-dip galvanization Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around . When expo ...

, mechanical deposition, or

electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...

. Because these bolts are designed to be used in structural applications the threaded length of the bolts are shorter to keep the threads out of the joint.

References

{{ASTM standards ASTM standards Screws Structural steel