ISO P — Steel · P50
P50 — High-strength steel
Hardness range: 280–350 HB. 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 — P50
- ISO designation
- P50 (ISO P — Steels)
- Material
- High-strength steel
- Hardness
- 280–350 HB
- 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 high-strength steel — starting point
- ISO application class
- P (steel), high-strength. Higher strength means higher cutting forces and heat, so run a tougher grade and a lower speed, with a rigid setup. 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
- Tough CVD-coated carbide, P25–P35, with a secure edge.
- Geometry
- Negative geometry with a honed edge for roughing security; rigid clamping and short overhang.
- Starting parameters
- Vc ≈ 120–220 m/min (lower than mild steel), fn ≈ 0.10–0.35 mm/rev. Confirm in the advisor or on a sample part.
high-strength steel: what goes wrong, and what to check first
- High cutting forces and deflection
- High-strength steel pushes back; shorten overhang, clamp rigidly, use a robust edge.
- Crater and flank wear from heat
- Use a CVD grade and ease the speed.
- Plastic deformation
- If the edge rounds or depresses it is too hot; drop Vc and feed or use a harder, more deformation-resistant grade.
- Chatter
- Rigidity first; then a robust edge.
Reference data
Insert grade index
ISO insert-code index
CNMG120408 — general turning
CCMT09T304 — positive finishing
Tool-wear diagnosis
Get cutting parameters for High-strength steel
The AI advisor maps your specific material condition and operation to a verified insert grade, coating, and Vc/fn range — with live search across the latest tooling catalogs.
Related materials