ASTM, SAE and ISO Grade Markings for Steel Fasteners

Download a complimentary PDF of our Fastener Markings chart. Contact American Fastener with any questions or for a custom quote.

Identification
Grade Mark		 Specification Fastener
Description		 Material Nominal Size
Range (in.)		 Mechanical Properties
Proof
Load (psi)		 Yield
Strength
Min (psi)		 Tensile
Strength
Min (psi)
NoGradeMark SAE J429
Grade 1		 Bolts,
Screws,
Studs		 Low or
Medium Carbon Steel		 1/4 thru
1-1/2		 33,000 36,000 60,000
ASTM A307
Grades A&B		 Low Carbon
Steel		 1/4 thru 4 — —
SAE J429
Grade 2		 Low or
Medium Carbon Steel		 1/4 thru
3/4 Over 3/4 to 1-1/2		 55,000
33,000		 57,000
36,000		 74,000
60,000
NoGradeMark SAE J429
Grade 4		 Studs Medium
Carbon Cold Drawn Steel		 1/4 thru
1-1/2		 — 100,000 115,000
B5 ASTM A193
Grade B5		 AISI 501 1/4 Thru 4 — 80,000 100,000
B6 ASTM A193
Grade B6		 AISI 410 85,000 110,000
B7 ASTM A19 3
Grade B7		 AISI 4140,
4142, OR 4105		 1/4 thru 2-1/2 Over 2-1/2 thru 4Over 4 thru 7 — —- 105,000
95,00075,000		 125,000
115,000100,000
B16 ASTM A193
Grade B16		 CrMoVa
Alloy Steel		 105,000
95,00085,000		 125,000
115,000100,000
B8 ASTM A193
Grade B8		 AISI 304 1/4 and larger — 30,000 75,000
B8C ASTM A193
Grade B8C		 AISI 347
B8M ASTM A193
Grade B8M		 AISI 316
B8T ASTM A193
Grade B8T		 Bolts, Screws, Studs for High-Temperature Service AISI 321 1/4 and
larger		 — 30,000 75,000
B8 ASTM A19 3
Grade B8		 AISI 304 Strain Hardened 1/4 thr 3/4 Over 3/4 thru 1Over 1 thru 1-1/4Over 1-1/4 thru 1-1/2 — —— 100,000
80,00065,000

FASTENER IDENTIFICATION
MARKING

Grade
Identification
Marking		 Specification Material Nominal Size In. Proof
LoadStressksi		 Hardness
Rockwell		 See
Note
Min Max
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
ASTM A563
– Grade C		 Carbon
Steel
May be Quenchedand Tampered		 1/4 thru 4 144 B78 C38 5
ASTM A563
– Grade C3		 Atmospheric
CorrosionResistant SteelMay be Quenchedand Tampered		 1/4 thru 4 144 B78 C38 5,9
ASTM A563
– Grade D		 Carbon
Steel
May be Quenchedand Tampered		 1/4 thru 4 150 B84 C38 6
ASTM A563
– Grade DH		 Carbon
Steel
Quenchedand Tampered		 1/4 thru 4 175 C24 C38 6
ASTM A563
– Grade DH3		 Atmospheric
CorrosionResistant Steel,Quenchedand Tampered		 1/4 thru 4 175 C24 C38 5,9
ASTM A194
– Grade 1		 Carbon
Steel		 1/4 thru 4 130 B70 — 7
ASTM A194
– Grade 2		 Medium
Carbon Steel		 1/4 thru 4 150 159 352 7,8
ASTM A194
– Grade 2H		 Medium
Carbon
Steel, Quenchedand Tempered		 1/4 thru 4 175 C24 C38 7
ASTM A194
– Grade 2HM		 Medium
Carbon
Steel, Quenchedand Tempered		 1/4 thru 4 150 159 237 7,8
ASTM A194
– Grade 4		 Medium
Carbon
Alloy Steel,Quenchedand Tempered		 1/4 thru 4 175 C24 C38 7
ASTM A194
– Grade 7		 Medium
Carbon
Alloy Steel,Quenchedand Tempered		 1/4 thru 4 175 C24 C38 7
ASTM A194
– Grade 7M		 Medium
Carbon
Alloy Steel,Quenchedand 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 —
  11. ASTM A563 — Carbon and Alloy Steel Nuts. ASTM A194/A194M — Carbon and Alloy Steel Nuts for Bolts for High Pressure and High Temperature Service.