Starting cutting speed in m/min and sfm, feed in mm/rev and ipr, the carbide grade class and the setup by operation for AISI P20 (40CrMnMo7). The numbers are the published P20 Alloy steel (heat treated) sub-group starting band; the designations are on the cross-reference page.
| Item | Value |
|---|---|
| ISO 513 group | P Steel |
| Sub-group | P20 Alloy steel (heat treated) |
| Sub-group hardness / condition | 200–300 HB |
| Category | Mold steel (pre-hardened) |
| EN / Werkstoffnummer | 40CrMnMo7 · 1.2311 |
Hardness is the range published for the whole P20 Alloy steel (heat treated) sub-group on our material guide; the delivery condition of your AISI P20 may sit anywhere inside it or outside it.
| Condition | Vc m/min | Vc sfm | Feed mm/rev | Feed ipr |
|---|---|---|---|---|
| P20 Alloy steel (heat treated), 200–300 HB | 150–250 | 490–820 | 0.10–0.40 | .004–.016 |
Sub-group starting values for carbide inserts, from P20 Alloy steel (heat treated). They describe the whole sub-group and are not tuned to AISI P20. sfm and ipr are converted from the metric values (1 m/min = 3.281 sfm, 25.4 mm = 1 in). The published band is per sub-group, not per operation; the table below gives the setup by operation. Convert Vc to spindle speed with the speeds & feeds calculator, and see the speeds & feeds guide for the ISO P group range.
| Operation | Geometry | Coating family | Coolant | First check |
|---|---|---|---|---|
| Roughing | Negative geometry, economical for roughing | CVD-coated carbide with a hard top layer for crater resistance | Check coolant delivery | Crater wear on the rake face: ease Vc |
| Finishing | Positive geometry for finishing | CVD-coated carbide | Check coolant delivery | Plastic deformation: edge too hot, drop Vc and feed |
| Interrupted cut | Honed or chamfered edge for security | CVD-coated carbide | Check coolant delivery | Edge security in interruptions; lower the band as hardness climbs |
| Low rigidity / thin wall | Positive geometry for thin walls and low-rigidity setups | CVD-coated carbide | Check coolant delivery | Built-up edge at low speed: raise Vc |
Setup rows are the selection table of the P20 Alloy steel (heat treated) guide. They carry no speeds, so they do not change the starting band above.
Same sub-group, same starting band: AISI H13 · AISI O1 · AISI O2 · AISI H11
CVD-coated carbide for crater resistance. Heat-treated alloy steels like 42CrMo4 / 4140 (≈ 28–34 HRC) reward a hard CVD top layer: roughing around P25–P35, finishing around P10–P20.
The P, M, K, N, S or H number inside a grade range describes what the grade is built for, not the workpiece sub-group number, and the two scales must not be matched to each other. We name no single grade here: none of our published sources ties a named grade to this alloy. Pick by ISO class, then compare what the makers publish on the ISO P grade list and in the grade chart.
EN 40CrMnMo7, Werkstoffnummer 1.2311, US AISI P20 (UNS T51620). The full table, with the nearest-match flags, is on the P20 / 1.2311 cross-reference page.
Delivered pre-hardened around 28-34 HRC and machined in that state: firmly P20-position work. 1.2738 is the nickel-alloyed P20 variant for thicker sections and cuts similarly.
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The published starting band for the P20 Alloy steel (heat treated) sub-group is 150–250 m/min (490–820 sfm) at 0.10–0.40 mm/rev (.004–.016 ipr). It is a starting band for the whole sub-group, not a value tuned to AISI P20, so confirm on a sample part and adjust for condition, tool and rigidity.
CVD-coated carbide for crater resistance. Heat-treated alloy steels like 42CrMo4 / 4140 (≈ 28–34 HRC) reward a hard CVD top layer: roughing around P25–P35, finishing around P10–P20. Pick the grade by ISO class rather than by brand name, then confirm the exact grade for your condition. We name no single grade here because none of our published sources ties a named grade to this alloy.
EN 40CrMnMo7 (Werkstoffnummer 1.2311); US: AISI P20 (UNS T51620); JIS: none listed. Entries marked nearest are the closest commonly-cited counterpart, not a same-composition equivalent.
The advisor compares what the makers publish for your material and operation and shows the source behind each answer, or tells you it could not verify.