Summary
ASTM A668 covers untreated and heat-treated carbon and alloy steel forgings for general industrial use. A668 cover carbon forgings in six classes, and alloy steel forgings in seven classes. Other forging specifications are available for specific applications. A common item Portland Bolt supplies that is made to ASTM A668 are Clevises as used in tie rod assemblies. The standard class is class A, although other classes can be quoted upon request. Available strength in kips per AISC available on our website.
A668 Chemical Requirements
| Element | Classes A to F and AH to FH | Classes G to N and GH to NH |
|---|---|---|
| Manganese % max | 1.35 | - |
| Phosphorous % max | 0.050 | 0.040 |
| Sulfur % max | 0.050 | 0.040 |
A668 Mechanical Requirements
| Class | Size, inches | Tensile, min ksi | Yield, min ksi | Elong, % min in 2” | RA, % min | Hardness, HBN |
|---|---|---|---|---|---|---|
| A | Up to 20 | 47 | - | - | - | 183 max |
| B | Up to 20 | 60 | 30 | 24 | 36 | 120-174 |
| C | Up to 12 | 66 | 33 | 23 | 36 | 137-183 |
| 12 to 20 | 66 | 33 | 22 | 34 | 137-183 | |
| D | Up to 8 | 75 | 37.5 | 24 | 40 | 149-207 |
| 8 to 12 | 75 | 37.5 | 22 | 35 | 149-207 | |
| 12 to 20 | 75 | 37.5 | 20 | 19 | 149-207 | |
| Over 20 | 75 | 37.5 | 19 | 30 | 149-207 | |
| E | Up to 8 | 85 | 44 | 25 | 40 | 174-217 |
| 8 to 12 | 85 | 44 | 23 | 37 | 174-217 | |
| 12 to 20 | 83 | 43 | 22 | 35 | 174-217 | |
| F | Up to 4 | 90 | 55 | 20 | 39 | 187-235 |
| 4 to 7 | 85 | 50 | 20 | 39 | 174-217 | |
| 7 to 10 | 85 | 50 | 19 | 37 | 174-217 | |
| 10 to 20 | 82 | 48 | 19 | 36 | 174-217 | |
| G | Up to 12 | 80 | 50 | 24 | 40 | 163-207 |
| 12 to 20 | 80 | 50 | 22 | 38 | 163-207 | |
| H | Up to 7 | 90 | 60 | 22 | 44 | 187-235 |
| 7 to 10 | 90 | 58 | 21 | 42 | 187-235 | |
| 10 to 20 | 90 | 58 | 18 | 40 | 187-235 | |
| J | Up to 7 | 95 | 70 | 20 | 50 | 197-255 |
| 7 to 10 | 90 | 65 | 20 | 50 | 187-235 | |
| 10 to 20 | 90 | 65 | 18 | 48 | 207-255 | |
| K | Up to 7 | 105 | 80 | 20 | 50 | 212-269 |
| 7 to 10 | 100 | 75 | 19 | 50 | 207-269 | |
| 10 to 20 | 100 | 75 | 18 | 48 | 207-269 | |
| L | Up to 4 | 125 | 105 | 16 | 50 | 255-321 |
| 4 to 7 | 115 | 95 | 16 | 45 | 235-302 | |
| 7 to 10 | 110 | 85 | 16 | 45 | 223-293 | |
| 10 to 20 | 110 | 85 | 14 | 40 | 223-293 | |
| M | Up to 4 | 145 | 120 | 15 | 45 | 293-352 |
| 4 to 7 | 140 | 115 | 14 | 40 | 285-341 | |
| 7 to 10 | 135 | 110 | 13 | 40 | 269-331 | |
| 10 to 20 | 135 | 110 | 12 | 38 | 269-341 | |
| N | Up to 4 | 170 | 140 | 13 | 40 | 331-401 |
| 4 to 7 | 165 | 135 | 12 | 35 | 331-401 | |
| 7 to 10 | 160 | 130 | 11 | 35 | 321-388 | |
| 10 to 20 | 160 | 130 | 11 | 35 | 321-402 | |
| Classes with an added ‘H’ are supplied on the basis of hardness values only. For example, AH. Classes A-F are carbon steel, classes G-N are alloy steel | ||||||
A668 Heat Treatment
| Class | Heat Treatment |
|---|---|
| A | Untreated |
| B | Annealed, or normalized, or normalized and tempered |
| C | Annealed, or normalized, or normalized and tempered |
| D | Annealed, or normalized, or normalized and tempered |
| E | Normalized and tempered or double normalized and tempered |
| F | Quenched and tempered, or normalized, quenched and tempered |
| G | Annealed, or normalized, or normalized and tempered |
| H | Normalized and tempered |
| J | Normalized and tempered, or normalized, quenched and tempered |
| K | Normalized, quenched and tempered |
| L | Normalized, quenched and tempered |
| M | Normalized, quenched and tempered |
| N | Normalized, quenched and tempered |
| Classes with an added ‘H’ are supplied on the basis of hardness values only. For example, AH. | |