Grades

ASTM A307 Grade A

This specification is manufactured from low-carbon mild steel and  covers your everyday, run of the mill bolts. Stock finishes include plain black, zinc plated, and hot-dip galvanized. One end of each rod requires a permanent grade symbol and manufacturer’s identifier, however this requirement is largely ignored due to their implementation in noncritical applications and the fact that they are often cut to length in the field.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
1⁄4" - 4" - - 60 ksi min 18 min - B69 B100

ASTM A307 Grade B

This low-carbon, mild steel bolt specification covers heavy hex bolts and fully threaded studs that are intended for cast iron flanged joints in piping systems with cast iron flanges. A307 Grade B differs from A307 Grade A in that it has a maximum tensile strength requirement. Common finishes include plain black, zinc, and hot-dip galvanized. One end of each rod requires a permanent grade symbol and manufacturer’s identifier.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
1⁄4" - 4" - - 60 min
100 max		 18 - B69 B95

ASTM F1554 Grades 36, 55, and 105

This specification covers anchor bolts that are designed for anchoring structural supports to concrete foundations. Bolts under this specification can conform to a headed bolt, straight rod or bent anchor bolt configuration. There are three grades within this specification, 36, 55, or 105.  These grade numbers represent the minimum yield strength (ksi) requirement of the anchor bolt. The bolts are color coded at the end that will project from the concrete to easily identify the grade used in the field (Grade 36: Blue, Grade 55: Yellow, Grade 105: Red). Permanent stamping with grade symbol and manufacturer’s identifier instead of color coding is a supplementary requirement.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
ASTM F1554 Grade 36Grade 36 1⁄2" - 4" - 36 58 min
80 max		 23 40 - -
ASTM F1554 Grade 55Grade 55 1⁄2" - 2" - 55 75 min
95 max		 21 30 - -
21⁄4"- 21⁄2" 21 30
23⁄4" - 3" 21 30
31⁄4" - 4" 21 30
ASTM F1554 Grade 105Grade 105 1⁄2" - 3" - 105 125 min
150 max		 15 45 - -

ASTM A449

The A449 specification is a high strength grade manufactured from a medium carbon or alloy steel which undergoes a heat-treating process to develop its strength. It is intended for general engineering applications.

Many engineers incorrectly specify A325 all thread rod, which is not a proper specification due to fact that A325 requires a forged head. ASTM A449 is virtually identical in chemistry and strength to the ASTM A325 specification in diameters 1/2″ – 1″; however, A449 is more flexible considering it is not restricted to a specific configuration. If you have a project with A325 all thread rod specified, have the engineer of record consider moving to an A449 grade instead for diameters 1″ and less. Common finishes are plain black and hot-dip galvanized. One end of each rod requires a permanent grade symbol and manufacturer’s identifier.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
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 A193 Grade B7

This specification is the other primary grade of all thread rod that is mass produced and readily available off the shelf. It is made from a medium-carbon, alloy steel that has been quenched and tempered to reach its higher strength. This grade of all thread is designed for high temperature or high pressure applications and intended for use in flanges, valves, pressure vessels and fittings.

It is important to note that in this specification, the threading standard for rods above 1” in diameter is 8 threads per inch (tpi). However, B7 threaded rod with Unified National Coarse (UNC) threads is also readily available. Both threading options are stock items so make sure to double check which thread pattern you need for your application. Common finishes are plain black and hot-dip galvanized. One end of each rod requires a permanent grade symbol and manufacturer’s identifier.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
1⁄4" - 21⁄2" - 105 125 16 50 - C35
25⁄8" - 4" 95 115 16 50 C35
41⁄8" - 7" 75 100 18 50 C35

ASTM A320 Grade L7

This specification is designed for rods being used in low temperature applications. It is made from medium-carbon, alloy steel which undergoes a heat-treating process to reach the required strength properties and requires a Charpy impact test to ensure its performance at low temperatures. Common finishes are plain black and hot-dip galvanized. One end of each rod requires a permanent grade symbol and manufacturer’s identifier stamp. Please note that rods above 1” in diameter require 8 threads per inch (tpi) unless otherwise specified.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
1⁄4" - 21⁄2" - 105 125 16 50 - -

ASTM A354 Grade BC

This specification covers quenched and tempered alloy steel bolts, studs and other fasteners 4” in diameter and under. This is a high-strength specification that does not have configuration limitations and is used for general applications.  Common finishes are plain black and hot-dip galvanized. One end of each rod requires a permanent grade symbol and manufacturer’s identifier.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
1⁄4" - 21⁄2" 105 109 125 16 50 C26 C36
25⁄8" - 4" 95 94 115 16 45 C22 C33

ASTM A354 Grade BD

This grade covers medium carbon, alloy steel that has been quenched and tempered to reach its high strength requirements.  It is virtually identical to the A490 specification in chemical and mechanical properties; however, it does not have the configuration limitations that A490 has.  If you have a project with A490 all thread rod specified, you should ask the Engineer of Record to consider A354 Grade BD in its place. A354 Grade BD is higher in strength than the other grades listed on this page and is subject to the risk of hydrogen embrittlement when plated or galvanized.  One end of each rod requires a permanent grade symbol and manufacturer’s identifier.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max
1⁄4" - 21⁄2" 120 130 150 14 40 C33 C39
25⁄8" - 4" 105 115 140 C31 C39

SAE J429 Grades 2, 5, and 8

The J429 specification covers requirements for fasteners used for automotive purposes, OEM applications, and other related industries. There are three common grades (2, 5 and 8) that readily available or can be made as fully threaded rods. There are ASTM specifications that have similar strength properties which may be easier to find in the form of all thread rod than their SAE equivalent. SAE threaded rods do not require permanent grade markings on the ends of the rods like many ASTM specifications do. Common finishes include plain black, zinc plated, and hot-dip galvanized for Grades 2 and 5. Grade 8 is typically provided plain finish only due to the potential risk of hydrogen embrittlement when plated or galvanized.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max

Grade 1		 1⁄4" - 11⁄2" 33 36 60 18 35 B70 B100

Grade 5		 1⁄4" - 3⁄4" 55 57 74 18 35 B80 B100
7⁄8" - 11⁄2" 33 36 60 18 B70 B100

Grade 8		 1⁄4" - 11⁄2" 120 130 150 12 35 C33 C39

Stainless Steel

Stainless steel all thread rod is common in the maketplace and is sold under several different ASTM specifications. The two most common forms of stainless all thread rod are bought and sold simply as AISI Type 304 or Type 316 stainless steel. However, stainless steel all thread rod is often specified under a variety of ASTM specifications including A193, A320, and F593.  The type of stainless steel desired for the project will be specified as a grade within the A193 and A320 specifications or as a alloy group and condition within the F593 specification.

Grade Marking Nominal Size Mechanical Properties Hardness Rockwell
Proof Load Yield Str. Tensile Str. Elong. % R.A. % Min Max

Grade B8
Class 1		 All - 30 75 30 50 223 max 35 max

Grade B8M
Class 1		 All 30 75 30 50 223 max 96 max

Grade B8
Class 2		 Up to 3/4 100 125 12 35 321 max 35 max
7/8 - 1 80 115 15 35
1-1/8 - 1-1/4 65 105 20 35
1-3/8 - 1-1/2 50 100 28 45

Grade B8M
Class 2		 Up to 3/4 95 110 15 45 321 max 35 max
7/8 - 1 80 100 20 45
1-1/8 - 1-1/4 65 95 25 45
1-3/8 - 1-1/2 50 90 30 45

ASTM A36

ASTM A36 is a steel grade, not a fastener specification. Technically, all thread rod made from A36 steel should be ordered to a fastener specification such as A307 Grade A, A307 Grade B, F1554 Grade 36, or SAE J429 Grade 2. The appropriate fastener specification will depend on the application. However, some companies stock all thread rod manufactured from A36 steel and can certify it as such upon request.