ASTM A449 Types

ASTM A449 is made in two different types of materials, Type 1 and Type 3.

ASTM A449 Type 1

A449 bolts are most commonly manufactured in Type 1 material. This is a medium carbon or alloy steel that undergoes a quench and tempering process to meet the mechanical properties of the specification. Because these bolts are prone to corrosion from natural elements, they are often hot-dip galvanized or zinc plated to prevent rust if used in exterior applications.

ASTM A449 Type 3

A449 fasteners made to Type 3 specification are manufactured from weathering steel. Weathering steel has atmospheric corrosion resistance and weather properties. The steel is designed to weather and rust over time but not corrode. Unlike Type 1 which has a coating to protect it from rusting, Type 3 bolts use their rust as a protective coating to seal the bolt and prevent further corrosion.

Grade Marking Specification Material and Treatment Nominal Size (In.) Mechanical Properties Hardness Rockwell
Proof Load Min (ksi) Yield Strength Min (ksi) Tensile Strength Min (ksi) Elong % Min [9] RA % Min [10] Min Max
ASTM A325 Type 1 A325 Type 1 Medium Carbon Steel, Q & T 1⁄2” – 11⁄2“ 85 92 120 14 35 C25 C34
ASTM A325 Type 3 A325 Type 3 Atmospheric Corrosion Resistant Steel, Q & T
ASTM A449 Type 1 A449 Type 1 Medium Carbon Steel, Q & T 1⁄4” – 1″ 85 92 120 14 35 C25 C34
11⁄8” – 11⁄2“ 74 81 105 C19 C30
15⁄8” – 3″ 55 58 90 B91 B100
ASTM A449 Type 3 A449 Type 3 Weathering Steel, Q & T 1⁄4” – 1″ 85 92 120 14 35 C25 C34
11⁄8” – 11⁄2“ 74 81 105 C19 C30
15⁄8” – 3″ 55 58 90 B91 B100

The way to distinguish between the two grades is the head marking. Type 1 bolts have a manufacturer’s logo (PB) with the grade symbol underneath. Type 3 bolts have the grade symbol underlined to distinguish that it is Type 3 as shown in the tables above.