BOLT GRADES, STRENGTH AND MARKINGS

Bolt grades, strength and bolt grade markings for steel bolts as designated by ASTM and SAE .

Bolt Strength Chart
Bolt Grade
Markings
Bolt
Grades
Bolt
Material
Bolt
Size (in)
Min. Bolt Strength (10^3 psi)
Proof Tensile Yield
Bolt Mark Identifier Grade 2 and Grade 4 SAE Grade 1 Low or medium carbon 1/4 to 3/2 33 60 36
ASTM A307 Low carbon 1/4 to 3/2 33 60 36
SAE Grade 2 Low or medium carbon 1/4 to 3/4 55 74 57
7/8 to 3/2 33 60 36
SAE Grade 4 Medium carbon, cold drawn 1/4 to 3/2 65 115 100
Bolt Mark Identifier Grade 5 SAE Grade 5 Medium carbon, quench and temper 1/4 to 1 85 120 92
ASTM A449 9/8 to 3/2 74 105 81
ASTM A449 7/4 to 3 55 90 58
Bolt Mark Identifier 5.2 SAE Grade 5.2 Low-carbon martensite, quench and temper 1/4 to 1 85 120 92
Bolt Mark Identifier A325 Type 1 ASTM A325, Type 1 Medium carbon, quench and temper 1/2 to 1 85 120 92
9/8 to 3/2 74 105 81
Bolt Mark Identifier A325 Type 2 ASTM A325, Type 2 Low-carbon martensite, quench and temper 1/2 to 1 85 120 92
9/8 to 3/2 74 105 81
Bolt Mark Identifier A325 Type 3 ASTM A325, Type 3 Weathering steel, quench and temper 1/2 to 1 85 120 92
9/8 to 3/2 74 105 81
Bolt Mark Identifier A354 Grade BC ASTM A354, Grade BC Weathering steel, quench and temper 1/4 to 5/2 105 125 109
11/4 to 4 95 115  
Bolt Mark Identifier SAE Grade 7 SAE Grade 7 Medium-carbon alloy, quench and temper 1/4 to 3/2 105 133 115
Bolt Mark Identifier SAE Grade 8 SAE Grade 8 Medium-carbon alloy, quench and temper 1/4 to 3/2 120 150 130
ASTM A354, Grade BD Alloy steel, quench and temper 1/4 to 3/2 120 150 130
Bolt Mark Identifier SAE Grade 8.2 SAE Grade 8.2  Low-carbon martensite, quench and temper 1/4 to 1 120 150 130
Bolt Mark Identifier ASTM A490, Type 1 ASTM A490, Type 1 Alloy steel, quench and temper 1/2 to 3/2 120 150 130
Bolt Mark Identifier ASTM A490, Type 3 ASTM A490, Type 3 Weathering steel, quench and temper

Note: Minimum strengths are strengths exceeded by 99 percent of fasteners.

Reference: