ASTM A490 andASTM A490M areASTM International standards for heavy hex structuralbolts made fromalloy steel. The imperial standard is officially titledStandard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength, while themetric standard (M) is titledStandard Specification for High-Strength Steel Bolts, Classes 10.9 and 10.9.3, for Structural Steel Joints.[1][2]
In 2016, specifications A325 and A490 were officially withdrawn by ASTM and replaced by ASTM F3125.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.[3]
There are also three connection types defined:[4]
These bolts are equivalent toASTM A325 bolts in application and geometry, but are made to a higher strength. The imperial grades are made to the same strength specifications asASTM A354 grade BD. The metric grades are made to the same strength specifications asASTM F568M property class 10.9.[5] Also, unlike their weaker counterparts they may not be coated byhot-dip galvanization,mechanical deposition, orelectroplating.[4]
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.[4]
| Grade identification marking | Specification | Nominal size range [in] | Proof strength[ksi] | Yield strength (min) [ksi] | Tensile strength (min) [ksi] | Core hardness [Rockwell] |
|---|---|---|---|---|---|---|
 | ASTM A490 Type 1 | 1⁄2–1-1⁄2 | 120 | 130[7] | 150 minimum 173 maximum[1] | C33–38 |
 | ASTM A490 Type 2 (withdrawn) | 1⁄2–1 | ||||
 [8] | ASTM A490 Type 3 | 1⁄2–1-1⁄2 |
| Grade identification marking | Specification | Nominal size range [mm] | Proof strength [MPa] | Yield strength (min) [MPa] | Tensile strength (min) [MPa] | Core hardness [Rockwell] |
|---|---|---|---|---|---|---|
 | ASTM A490M Type 1 | 12–36 | 830 | 940 | 1040 | C33–39 |
 | ASTM A490M Type 2 (withdrawn)[10] | |||||
 | ASTM A490M Type 3 |