ISO P — Steel · P30
P30 — Case-hardened steel
Hardness range: 58–62 HRC surface. Part of the ISO P — Steels group. Steel is the most widely machined material. Carbon and alloy steels are the target material for the majority of turning and milling operations. Hardness ranges from ~125 HB (low-carbon) to 350 HB (high-strength structural). CVD-coated carbide (TiCN/Al₂O₃ multilayer) dominates. Positive geometry for finishing, negative for heavy roughing.
Material profile — P30
- ISO designation
- P30 (ISO P — Steels)
- Material
- Case-hardened steel
- Hardness
- 58–62 HRC surface
- ISO group colour
- Steel
Tooling guidance — P-group
- Group summary
- CVD-coated carbide at Vc 200–400 m/min. Positive geometry for finishing, negative for roughing.
Insert selection for case-hardened steel — starting point
- ISO application class
- P / H. The first question is whether you cut before carburizing (soft core, normal P-class) or after (hard 58–62 HRC case, effectively hard turning). Match the ISO P class across brands rather than the brand name (Sandvik, Kennametal, Iscar, Walter, Seco and Mitsubishi each publish one), then confirm the exact grade for your condition.
- Grade & coating
- Soft pre-carburized state: P-class CVD carbide. Hardened case (58–62 HRC): CBN or hard ceramic, like hard turning, with a honed/chamfered edge.
- Geometry
- For the hardened case, negative geometry with a chamfer plus hone and a rigid setup; for the soft state, normal turning geometry.
- Starting parameters
- Soft state Vc ≈ 180–280 m/min; hardened case with CBN Vc ≈ 100–180 m/min, fn ≈ 0.05–0.15 mm/rev. Confirm in the advisor or on a sample part.
case-hardened steel: what goes wrong, and what to check first
- Edge chipping cutting the hard case
- The hard 58–62 HRC case behaves like hard turning; use CBN with a chamfered honed edge and a rigid setup.
- Case-to-core transition shock
- Cutting through the hard case into soft core is an interruption in hardness; favour edge security.
- White layer on the case
- Keep the edge fresh and the speed in band.
- Wrong grade for the state
- Confirm before or after carburizing first; it changes everything.
Reference data
Insert grade index
ISO insert-code index
CNMG120408 — general turning
CCMT09T304 — positive finishing
Tool-wear diagnosis
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