6F5 is the British die-steel designation for a nickel-chromium alloy tool steel, carried in Germany as DIN 55NiCr10 and Werkstoffnummer 1.2718, with an AFNOR cross-reference of 55NC10. With roughly 0.50-0.57% carbon and a substantial nickel addition around 2.5-3.0%, plus a modest chromium content, 6F5 is built around the same principle as its sister grade 6F3: nickel drives deep hardenability and toughness through heavy sections, letting large tooling harden evenly rather than developing a hard shell over a soft, unhardened core.

Compared to the more heavily alloyed 6F3, 6F5 carries no molybdenum or vanadium, which simplifies the alloy and keeps cost down while still delivering good through-hardening and high toughness for its carbon level. It is commonly used for die blocks, forging dies, and other large tooling where consistent hardness and resistance to cracking under repeated impact are more important than maximum wear resistance. Like other nickel-alloyed die steels, it responds well to tempering adjustments, giving toolmakers a way to trade hardness for toughness depending on the specific duty cycle of the tool.

Like 6F3, the nickel content in 6F5 makes it machine somewhat differently from a plain carbon or chromium-alloyed cold-work steel of similar hardness: the matrix is tougher and more ductile, which tends to produce longer chips and demands more attention to chip control than the annealed hardness (typically around 220 HB) alone would suggest. Cutting forces are moderate, but the material's resistance to shearing cleanly means edge geometry and chip breakers matter more here than raw speed.

6F5 is normally roughed and semi-finished in the annealed or lightly tempered condition, then hardened and finish-ground, so the bulk of metal removal happens before heat treatment. Rigid setups, adequate coolant, and coated carbide grades with good toughness handle the stock removal typical of die-block work well. As with other nickel-alloyed die steels, keeping the edge sharp on finishing passes helps avoid smearing or work-hardening the surface ahead of final grinding.

Speeds below are for the annealed condition (~210-230 HB).

Milling

Turning, parting, and grooving grade recommendations for 6F5 are not on file for this material yet. Browse the full turning/parting collection below for a grade suited to your hardness and finish requirements.