SAE J995 Technical Data

The SAE J995 specification is formally known as Mechanical and Material Requirements for Steel Nuts. The SAE J995 Standard covers the mechanical and material requirements for three grades of steel nuts ranging in size from ¼ to 1-1/2 inches with dimensions adhering to SAE J428 or ASME B18.18. The nuts in the standard are typically used in automotive and related engineering applications.

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SAE J995 Grades & Identification Markings

There are three grades of nuts within the SAE J995 Standard. The grades are 2, 5, and 8. As the grade number increases, the tensile strength of the nut increases. For each of the three grades, there are three acceptable styles of grade marking. Style A of marking is applicable to all sizes of nuts. Style B is applicable to hex nuts sized 5/8 inches or larger. Style C is applicable to nuts that are fabricated by cutting from a hex bar.

Grades & Identification Markings

Chemical Composition Requirements 1
NUT GradeC MaxMn MinP MaxS MaxGrade Identification Marking
20.55-0.12 20.15 3grade2
50.550.30.05 4,50.15 3,5grade5
80.550.30.040.15 6grade8


1. All values are for ladle analysis (percent by weight) and subject to standard variations for check analysis as given in SAE J409.
2. Resulfurized and rephosphorized material is not subject to rejection based on check analysis for sulfur.
3. If agreed between purchaser and producer, sulfur content may be 0.23 maximum.
4. Phosphorus content may be 0.13 maximum for acid bessemer steel only.
5. If agreed between purchaser and producer, sulfur content may be 0.35 maximum and phosphorus content may be 0.12 maximum provided that manganese content is 0.70 minimum.
6. If agreed between purchaser and producer, sulfur content may be 0.33 maximum provided that manganese content is 1.35 minimum.

SAE J995 Mechanical Properties

SAE J995 mechanical requirements specify the proof load the nut must be able to withstand according to the nut size, thread series, and nut type. The mechanical properties also include requirements for tensile stress areas and nut hardness limits.


Nut Grade258
Nut Size1/4 thru 1 1/21/4 thru 1 1/21/4 thru 11/4 thru 1Over 1 thru 1 1/2Over 1 thru 1 1/21/4 thru 1 1/21/4 thru 1 1/2
Thread SeriesUNC and 8UNUNF, 12 UN and FinerUNC and 8UNUNF, 12 UN and FinerUNC and 8UNUNF, 12UN and FinerUNC and 8UNUNF, 12UN and Finer
Nut TypeProof Load Stress, psi1Proof Load Stress, psi1Proof Load Stress, psi1Proof Load Stress, psi1Proof Load Stress, psi1Proof Load Stress, psi1Proof Load Stress, psi1Proof Load Stress, psi1
Hex Flange900008000012000010900010500094000150000150000
Hex Jam25400048000720006500063000570009000090000
Heavy Hex Jam25400048000720006500063000570009000090000
Hex Slotted2710006500096000870008400075000120000120000
Heavy Hex210000090000133000120000116000105000165000150000
Hex Thick210000090000133000120000116000105000165000150000
Hex Thick Slotted27900071000105000960009200084000132000120000
Hex High210000090000133000120000116000105000165000150000
Hex High Slotted27900071000105000960009200084000132000120000
Heavy Square7900071000105000960009200084000132000120000

1. The proof load in pounds for nuts is computed by multiplying the proof load stress, in psi (lbf/in2 ), for the nut grade, size, thread series, and type, as shown in Table 2, and tensile stress area in square inches (in2 ), for the applicable size and thread series shown in Table 3. (For tabulated values see Appendix A.) To convert the inch based pounds per square inch (psi) values above to metric Megapascal (MPa) units, multiply the above values by .00689.

2. Proof load stress values for hex jam, heavy hex jam, hex slotted, heavy hex, hex thick, heavy hex slotted, and hex thick slotted nuts are based on the requirement for hex nuts. Primarily, each value is derived from the ratio of the minimum thickness of the product involved to the minimum thickness of similar hex or square machine screw nuts and hex nuts (see B18.2.2) of the same size


Coarse Thread Series UNC Nominal Size and Threads Per InchCoarse Thread Series UNC Tensile Stress Area, sq in. Fine Thread Series UNF Nominal Size and Threads Per InchFine Thread Series UNF Tensile Stress Area, sq in. 8-Thread Series 8 UN Nominal Size and Threads Per Inch8-Thread Series 8 UN Tensile Stress Area, sq in.
1/4 - 200.03181/4 - 280.0364--
5/16 -180.05245/16 -240.0580--
3/8 - 160.07753/8 - 240.0878--
7/16 - 140.10637/16 - 200.1187--
1/2 - 130.14191/2 - 200.1599--
9/16 - 120.1829/16 - 180.203--
5/8 - 110.2265/8 - 180.256--
3/4 - 100.3343/4 - 160.373--
7/8 - 90.4627/8 - 140.509--
1 - 80.6061 - 120.6631 - 8 0.606
1-1/8 - 70.7631-1/8 - 120.8561-1/8 - 80.790
1-1/4 - 70.7631-1/8 - 120.8561-1/8 - 80.790
1-1/4 - 70.9691-1/4 - 121.0731-1/4 - 81.000
1-3/8 - 61.1551-3/8 - 121.3151-3/8 - 81.233
1-1/2 - 61.4051-1/2 - 121.5811-1/2 - 81.492



Nut GradeNominal Nut SizeHardness
21/4 thru 1-1/232 HRC max
51/4 thru 1-1/232 HRC max
81/4 thru 5/824-34 HRC
8Over 5/826-34 HRC
8Over 1 thru 1-1/226-36 HRC

SAE J995 Materials & Chemical Properties

The chemical composition requirements outlined by the SAE J995 Specification set the maximum amounts of carbon, phosphorus, and Sulphur as well as the minimum amount of manganese in the composition of the steel used to manufacture the nut.


Nut SizeMarking Lines1 WidthMarking Lines1 LengthMarking Lines1 Depth
1/4 and 5/160.0150.050.01
3/8 thru 9/
5/8 thru 7/
1 and larger0.030.120.01

1. For hex flange nuts, lines on the top of the flange may be up to two times the dimensions shown.