FCAFastener Corporation

Fastener Identification Marking

ASTM, SAE, and ISO Grade Markings and Mechanical Properties for Steel Fasteners | Back to Reference Data

Grade
Identification
Marking
Specification Material Nominal Size
In.
Proof Load
Stress
(ksi)
Hardness
Rockwell
See
Note
min. max.
No Mark
No Mark
ASTM A563 - Grade 0 Carbon Steel 1/4 thru 1-1/2 69 B55 C32 3,4
ASTM A563 - Grade A Carbon Steel 1/4 thru 1-1/2 90 B68 C32 3,4
ASTM A563 - Grade B Carbon Steel 1/4 thru 1 120 B69 C32 3,4
over 1 thru 1-
1/2
105
Grade C ASTM A563 - Grade C Carbon Steel
May be
Quenched
and Tempered
1/4 thru 4 144 B78 C38 5
Grade C3 ASTM A563 - Grade C3 Atmospheric
Corrosion
Resistant Steel
May be
Quenched
and Tempered
1/4 thru 4 144 B78 C38 5,9
Grade D ASTM A563 - Grade D Carbon Steel
May be
Quenched
and Tempered
1/4 thru 4 150 B84 C38 6
Grade DH ASTM A563 - Grade DH Carbon Steel
Quenched
and Tempered
1/4 thru 4 175 C24 C38 6
Grade DH3 ASTM A563 - Grade DH3 Atmospheric
Corrosion
Resistant Steel,
Quenched
and Tempered
1/4 thru 4 175 C24 C38 5,9
Grade 1 ASTM A194 - Grade 1 Carbon Steel 1/4 thru 4 130 B70 -- 7
Grade 2 ASTM A194 - Grade 2 Medium Carbon Steel 1/4 thru 4 150 159 352 7,8
Grade 2H ASTM A194 - Grade 2H Medium Carbon Steel, Quenched and Tempered 1/4 thru 4 175 C24 C38 7
Grade 2HM ASTM A194 - Grade 2HM Medium Carbon Steel, Quenched and Tempered 1/4 thru 4 150 159 237 7,8
Grade 4 ASTM A194 - Grade 4 Medium Carbon Alloy Steel,
Quenched
and Tempered
1/4 thru 4 175 C24 C38 7
Grade 7 ASTM A194 - Grade 7 Medium Carbon Alloy Steel,
Quenched
and Tempered
1/4 thru 4 175 C24 C38 7
Grade 7M ASTM A194 - Grade 7M Medium Carbon Alloy Steel,
Quenched
and Tempered
1/4 thru 4 150 159 237 7
See Note 1,2 10            

NOTES:

  1. In addition to the indicated grade marking, all grades, except A563 grades O, A and B, must be marked for manufacturer identification.
  2. The markings shown for all grades of A194 nuts are for cold formed and hot forged nuts. When nuts are machined from bar stock the nut must be additionally marked with the letter 'B'.
  3. Nuts are not required to be marked unless specified by the purchaser. When marked, the identification marking shall be the grade letter O, A or B.
  4. Properties shown are those of nonplated or noncoated coarse thread hex nuts.
  5. Properties shown are those of coarse thread heavy hex nuts.
  6. Properties shown are those of coarse thread heavy hex nuts.
  7. Properties shown are those of coarse 8-pitch thread heavy hex nuts.
  8. Hardnesses are Brinell Hardness Numbers.
  9. The nut manufacturer, at his option, may add other markings to indicate the use of atmospheric corrosion resistant steel.
  10. Specifications:
    ASTM A563 -- Carbon and Alloy Steel Nuts.
    ASTM A194/A194M -- Carbon and Alloy Steel Nuts for Bolts for High Pressure and High Temperature Service.