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.

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.

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

Insert grade index ISO insert-code index CNMG120408 — general turning CCMT09T304 — positive finishing Tool-wear diagnosis

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