CF-8 is a cast austenitic stainless steel and the casting-grade counterpart to wrought 304 — same basic 18% chromium, 8-11% nickel chemistry, but produced as a casting rather than rolled or forged bar and plate. It is defined under ASTM A743/A744 for corrosion- and heat-resistant castings and carries the Werkstoffnummer 1.4308, DIN/EN designation X6CrNi18-9, and JIS designation SCS13. Because it is a casting alloy, silicon content runs higher than wrought 304 to promote fluidity and castability, and the as-cast grain structure is coarser and less uniform than a wrought mill product.

CF-8 is the workhorse casting grade for valve bodies, pump casings and impellers, fittings, and other pressure-containing or corrosion-service components where the part geometry favors casting over machining from bar stock. It shares 304's basic corrosion resistance and non-magnetic, austenitic microstructure, and cannot be strengthened by heat treatment — only cold work increases its strength.

Ranges per ASTM A743/A744. The higher silicon maximum versus wrought 304 is intentional — it improves mold fluidity during casting. A composition table in this alloy's source content had been corrupted with data copy-pasted from an unrelated martensitic grade; it has been replaced here with verified ASTM A743 ranges.

CF-8 shares the gummy, work-hardening chip behavior of wrought 304, but the as-cast grain structure changes the picture in a few important ways. Castings are less homogeneous than wrought bar: grain size is coarser and can vary noticeably within a single part, porosity or sand/shrinkage inclusions may be present near the surface or in thicker sections, and the skin of a casting is often harder and more abrasive than the parent metal underneath due to sand or investment mold reaction. That skin can dull an edge quickly on the first pass even though the bulk material machines like ordinary austenitic stainless once you're through it.

Because of that, the first cut into a CF-8 casting should be treated more conservatively than a repeat pass on wrought bar — a tougher insert grade or a slightly reduced speed on the initial skin cut pays off in tool life. Once past the surface, the same fundamentals that apply to wrought 304 apply here: sharp, positive-rake geometry, firm feeds that avoid rubbing and work hardening, and good coolant to offset the alloy's low thermal conductivity.

Values assume favorable conditions on sound, machined-through material. Reduce speeds for the initial skin/surface cut on castings, which is often harder and more abrasive than the core.

Turning

Parting / Grooving

Milling