| Maximum Diameter of Round or Equivalent Round, in.a | |||||||
|---|---|---|---|---|---|---|---|
| Ftu, ksi | 0.5 | 0.8 | 1.0 | 1.7 | 2.5 | 3.5 | 5.0 |
| 270 & 280 | 300Mc | ||||||
| 260 | AISI 4340b | AISI 4340c | AISI 4340d | ||||
| 220 | AMS Gradesb,e | AMS Gradesc,e | D6ACb | D6ACc | |||
| 200 | AISI 8740 | AISI 4140 | AISI 4340b AMS Gradesb,e | AISI 4340c AMS Gradesc,e | AISI 4340d | D6ACc | |
| ≤180 | AISI 4130 and 8630 | AISI 8735 4135 and 8740 | AISI 4140 | AISI 4340b AMS Gradesb,e | AISI 4340c AMS Gradesc,e | AISI 4340d D6ACb | D6ACc |
- a This table indicates the maximum diameters to which these steels may be through hardened consistently by quenching as indicated. Any steels in this table may be used at diameters less than those indicated. The use of steels at diameters greater than those indicated should be based on hardenability data for specific heats of steel.
- b Quenched in molten salt at desired tempering temperature (“martempering”).
- c Quenched in oil at a flow rate of 200 feet per minute.
- d Quenched in water at a flow rate of 200 feet per minute.
- e 4330V, 4335V, and Hy-Tuf.