ISO M — Stainless Steel · M30
M30 — PH stainless (17-4PH)
Hardness range: 28–44 HRC. Part of the ISO M — Stainless Steel group. Stainless steel presents work-hardening as the main challenge. Austenitic grades (304, 316L) built-up-edge and notch-wear rapidly. Positive, sharp geometry with high-pressure coolant at 15–20 bar is standard. Consistent depth of cut prevents re-cutting the hardened chip ramp.
Material profile — M30
- ISO designation
- M30 (ISO M — Stainless Steel)
- Material
- PH stainless (17-4PH)
- Hardness
- 28–44 HRC
- ISO group colour
- Stainless Steel
Tooling guidance — M-group
- Group summary
- Work hardening is the main challenge. Sharp positive geometry, high-pressure coolant 15–20 bar, consistent DOC.
Insert selection for 17-4PH stainless — starting point
- ISO application class
- M (stainless), but 17-4PH machinability depends heavily on its heat-treat condition. Match the insert's ISO class across brands (Sandvik, Kennametal, Iscar, Walter, Seco and Mitsubishi); for aged material treat it as tougher and slower.
- Grade & coating
- PVD-coated M-class carbide for solution-annealed 17-4PH (~28–33 HRC). For aged H900 / H1025 (~40–44 HRC), use a harder, more wear-resistant grade and lower the speed.
- Geometry
- Positive honed edge and a rigid setup. High-pressure coolant.
- Starting parameters
- Annealed Vc ≈ 100–160 m/min; aged H900 lower, ~80–120 m/min. fn ≈ 0.10–0.25 mm/rev. Condition matters most — confirm in the advisor or on a sample part.
Selection table: 17-4PH stainless
| Operation | Geometry | ISO class | Coating family | Coolant | First check |
|---|---|---|---|---|---|
| Roughing | Positive honed edge, rigid setup | M (tougher and slower when aged) | PVD-coated M-class carbide; harder, more wear-resistant grade for aged H900 / H1025 | High-pressure coolant | Heat-treat condition: annealed versus aged drives grade and speed |
| Finishing | Positive honed edge | M (M-class grade) | PVD-coated M-class carbide | High-pressure coolant | Built-up edge: raise Vc into the band, coolant at the edge |
| Interrupted cut | Positive honed edge, rigid setup | M (tougher M-class grade) | Tougher PVD-coated carbide | High-pressure coolant | Edge chipping on aged material |
| Low rigidity / thin wall | Positive honed edge; rigid setup, short overhang | M (M-class grade) | PVD-coated M-class carbide | High-pressure coolant | Work-hardening: keep DOC above the hardened layer, never dwell |
17-4PH stainless: what goes wrong, and what to check first
- Condition surprise (annealed vs H900)
- The same part number machines very differently solution-annealed versus aged. Confirm the heat-treat condition first — it drives both grade and speed. See the tool-wear guide.
- Work-hardening
- Keep DOC above the previously hardened layer and never let the tool dwell.
- Notch wear / built-up edge
- Vary the depth of cut, raise Vc into the band, and aim coolant at the edge.
- Edge chipping on aged material
- Use a tougher grade, a honed edge, and a rigid setup.
Reference data
Frequently asked questions
What insert should I use for 17-4PH stainless?
A PVD-coated M-class carbide — but first confirm the condition: solution-annealed machines easier than aged H900. Match the ISO M class across brands and confirm the exact grade in the advisor.
Does 17-4PH condition (annealed vs H900) change machining?
Yes, a lot. Aged H900 (~44 HRC) needs a harder grade and a lower speed than solution-annealed (~30 HRC). Confirm the condition before choosing a grade and speed.
What cutting speed for 17-4PH with carbide?
Roughly Vc 100–160 m/min solution-annealed, lower (~80–120) for aged H900, fn 0.10–0.25 mm/rev. Treat this as a starting band and confirm on a sample part.
Why does my 17-4PH tool wear unevenly?
Usually work-hardening from an inconsistent depth of cut or a dwelling tool. Keep the depth of cut above the hardened layer and keep the tool moving.
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Grade designations in this group
Each page cross-references the EN, Werkstoffnummer, AISI/UNS and JIS designations for one material, with the ISO machining group it falls in.
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