Carbon Steel Bolt Grade Markings

In addition to the the indicated grade marking, all grades included in this table must be marked for manufacturer identification. While hex heads are shown, grade markings apply equally to products with other head configurations.

Grade Identification Marking Specification

Material

Nominal Size
(inch)
Proof Load Stress
(ksi)
Tensile Strength
(min ksi)
Rockwell Hardness
(min)
Rockwell Hardness
(max)
See Note
SAE J429- Grade 2 SAE J429 – Grade 2 Low or Medium Carbon Steel 1/4 thru 3/4 55 74 B80 B100 -
over 3/4 thru 1-1/2 33 60 B70 B100 -
ASTM A307 - Grade A ASTM A307 – Grade A Low or Medium Carbon Steel 1/4 thru 4 - 60 B69 B100 -
ASTM A307 Grade B ASTM A307 – Grade B Low or Medium Carbon Steel 1/4 thru 4 - 60 min
100 max
B69 B95 -
SAE J429 - Grade 5 SAE J429 – Grade 5 Medium Carbon Steel, Quenched and Tempered 1/4 thru 1 85 120 C25 C34 -
ASTM A449 - Type 1 ASTM A449 – Type 1 Medium Carbon Steel, Quenched and Tempered over 1 thru 1-1/2 74 105 C19 C30 -
over 1-1/2 thru 3 55 90 183 235 NOTE
ASTM A325 - Type 1 ASTM A325 – Type 1 Medium Carbon Steel, Quenched and Tempered 1/2 thru 1 85 120 C24 C35 NOTE
over 1 to 1-1/2 74 105 C19 C31 NOTE
ASTM A325 - Type 3 ASTM A325 – Type 3 Atmospheric Corrosion Resistant Steel, Quenched and Tempered 1/2 thru 1 85 120 C24 C35 NOTE
over 1 to 1-1/2 74 105 C19 C31 NOTE
ASTM A354 - Grade BC ASTM A354 – Grade BC Medium Carbon Alloy Steel, Quenched and Tempered 1/4 thru 2-1/2 105 125 C26 C36 -
over 2-1/2 thru 4 95 115 C22 C33 -
SAE J429 - Grade 8 SAE J429 – Grade 8 Medium Carbon Alloy Steel, Quenched and Tempered 1/4 thru 1-1/2 120 150 C33 C39 -
ASTM A354 - Grade BD ASTM A354 – Grade BD Medium Carbon Alloy Steel, Quenched and Tempered

 

1/4 thru 2-1/2 120 150 C33 C39 NOTE
over 2-1/2 thru 4 105 140 C31 C39 NOTE
ASTM A490 - Type 1 ASTM A490 – Type 1 Medium Carbon Alloy Steel, Quenched and Tempered 1/2 thru 1-1/2 120 150 min
170 max
C33 C38 -
ASTM A490 - Type 3 ASTM A490 – Type 3 Atmospheric Corrosion Resistant Steel, Quenched and Tempered 1/2 thru 1-1/2 120 150 min
170 max
C33 C38 NOTE