ASTM A194 Grade 2HM is a standard material specification for high tensile nuts and other internally threaded fasteners, made from carbon steel. Grade 2HM nuts can be produced by means of hot forging, cold forging or machining from heat treated bar stock. ASTM A194 specification covers requirements for chemical composition, heat treatment, hardness, proof load, etc., for Grade 2HM nuts.
Element |
Carbon Steel |
|---|---|
| CompositionA, % | |
| Carbon | 0.15 min |
| Manganese | 1.00 max |
| Phosphorus | 0.04 max |
| Sulfur | 0.05 max |
| Silicon | 0.40 max |
AThe intentional addition of Bi, Se, Te, and Pb is not permitted.
| Grade | Completed Nuts | Sample Nut After Heat Treatment | |||
|---|---|---|---|---|---|
| Brinell Hardness, BHN |
Rockwell Hardness | Brinell Hardness, BHN, min |
Rockwell Hardness, HRB, min |
||
| HRC | HRB | ||||
| 2HM | 159 - 235 | ... | 84 - 99 | 159 | 84 |
Heat Treatment: Grade 2HM shall be quenched and tempered at a temperature of at least 1150 °F [620 °C].
| Nominal Size, Inch. | Threads Per Inch | Proof Load, lbf | |
|---|---|---|---|
| Heavy HexA | HexB | ||
| 1/4 | 20 | 4 770 | 4 300 |
| 5/16 | 18 | 7 860 | 7 070 |
| 3/8 | 16 | 11 620 | 10 460 |
| 7/16 | 14 | 15 940 | 14 350 |
| 1/2 | 13 | 21 280 | 19 160 |
| 9/16 | 12 | 27 300 | 24 570 |
| 5/8 | 11 | 33 900 | 30 510 |
| 3/4 | 10 | 50 100 | 45 090 |
| 7/8 | 09 | 69 300 | 62 370 |
| 01 | 08 | 90 900 | 81 810 |
| 1-1/8 | 08 | 118 500 | 106 700 |
| 1-1/4 | 08 | 150 000 | 135 000 |
| 1-3/8 | 08 | 185 000 | 166 500 |
| 1-1/2 | 08 | 223 800 | 201 400 |
A: Based on proof stress of 150 000 psi.
B: Based on proof stress of 135 000 psi.
| Commonly Produced Grade 2HM Nuts | ||||
|---|---|---|---|---|
| Hex Nuts | Heavy Hex Nuts | Jam Nuts | Heavy Hex Jam Nuts | Castle Nuts |
| Coupling Nuts | Square Nuts | Thin Square Nuts | All Metal Lock Nuts | Dome Nuts |