Specification Library

Fastener Identification Marking

Grade Identification Marking Specifications Material Nominal Size Proof Load Stress Tensile Strength
Min.
ksi
Hardness Rockwell
Min. Max.
SAE J429 Grade 1 Low or Medium
Carbon Steel
1/4 thru 1-1/2 33 60 B70 B100
SAE J429 Grade 2 1/4 thru 3/4 over 3/4 thru 1-1/2

55

33

74

60

B80

B70

B100

B100

ASTM A307 – Grade A 1/4 thru 4 60 B69 B100
SAE J429 – Grade 5 Medium Carbon
Steel,Quenched
and Tempered
1/4 thru 1
over 1 thru 1-1/2
85 120 C25 C34
ASTM A449 – Type 1 74 105 C19 C30
ASTM A325 – Type 1
Refer to Note 4
Medium Carbon
Steel,Quenched
and Tempered
1/2 thru 1
over 1 to 1-1/2

85

74

120

105

C24

C19

C35

C31

ASTM A325 – Type 2 Low Carbon
Martensite Steel,
Quenched and
Tempered
ASTM A325 – Type 3
Refer to Note 5
Atmospheric
Corrosion Resistant
Steel,Quenched
and Tempered
1/2 thru 1
over 1 to 1-1/2

85

74

120

105

C24

C19

C35

C31

ASTM A354 -Grade BC Medium Carbon
Alloy Steel,
Quenched and
Tempered

1/4 thru 2-1/2

over 2-1/2 thru 4

105

95

125

115

C26

C22

C36

C33

SAE J429 – Grade 8 Medium Carbon
Alloy Steel,
Quenched and
Tempered
1/4 thru 1-1/2

120

120
105

150

150
140

C33

C33
C33

C39

C39
C39

ASTM A354 – Grade BD
Refer to Note 6
1/4 thru 2-1/2
over 2-1/2 thru 4
SAE J429 – Grade B2 Low Carbon Martensite Steel, Quenched and Tempered 1/4 thru 1 120 150 C33 C39
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 2 Low Carbon Martensite Steel, Quenched and Tempered 1/2 thru 1 120

150 min.

170 max.

C33 C38
ASTM A490 – Type 3
Refer to Note 5
Atmospheric Corrosion Resistant Steel, Quenched
and Tempered
1/2 thru 1-1/2 120

150 min.

170 max.

C33 C38
ASTM A-193 – Grade B7 4140 Alloy Steel Quenched and Tempered 1/2 to 3-1/2 105 125 min.

Notes regarding Fastener Identification Marking

  1. In addition to the indicated grade marking, all grades included in this table must be marked for manufacturer identification.
  2. While hex heads are shown, grade markings apply equally to products with other head configurations.
  3. Hardness are Brindell Hardness numbers.
  4. A325 Type 1 bolts may also be marked with 3 radial lines 120 degrees apart in addition to the A325 marking.
  5. The bolt manufacturer, at his option, may add other markings to indicate the use of atmospheric corrosion resistant steel.
  6. A354 Grade BD products, in sizes 1-1/2” and smaller, are identified as shown and, at the manufacturer’s option, may have the letters BD added. Larger sizes are marked only BD.
  7. Specifications:
    ASTM 325 High strength bolts for structural steel joints
    SAE J429 Mechanical and material requirements for externally threaded fasteners
    ASTM A307 Carbon steel externally threaded standard fasteners
    ASTM A449 Quenched and tempered steel bolts and studs
    ASTM A354 Quenched and tempered alloy steel bolts, studs and other externally threaded fasteners
    ASTM A490 Heat treated steel structural bolts, 150 ksi minimum tensile strength
    ASTM A193-B7 Quenched and tempered alloy steel heavy hex bolts