Maraging C250 is the workhorse mid-strength grade of the 18% nickel maraging steel family, and like every alloy in this group it earns its strength through a two-step "martensite + aging" process rather than conventional carbon hardening. Cooling from solution-annealing temperature transforms the very low-carbon, nickel-cobalt-molybdenum-titanium chemistry into a soft, dislocation-rich martensite that machines and cold-forms comparatively easily. A follow-up aging treatment at moderate temperature then precipitates fine nickel-molybdenum and nickel-titanium intermetallic compounds through that martensite, which is what actually delivers the strength — without the coarse carbide structure and brittleness that would come from hardening a similar-strength conventional alloy steel.

The "250" designation reflects the alloy's approximate minimum yield strength once fully aged — roughly 250,000 psi, or about 1,720 MPa — a step up from C200 thanks to higher molybdenum and titanium content. That combination of very high strength, good fracture toughness, and excellent dimensional stability through heat treatment makes C250 one of the most widely used maraging grades in aerospace landing gear and structural components, high-performance tooling, and precision shafting where both strength-to-weight ratio and reliability under load matter.

C250's machining behavior depends heavily on which side of the aging cycle the stock is on. In the solution-annealed (unaged) condition — typically around 30-32 HRC — the low-carbon martensite is comparatively soft and machines much like a mild alloy steel, with moderate cutting forces and predictable tool life. This is the condition most bar and forging stock arrives in, and it's when the bulk of roughing and semi-finish machining is normally done, before the part goes through its final aging heat treatment.

After aging, C250 reaches roughly 50-52 HRC, and the picture changes: cutting forces climb, tool wear accelerates, and any post-aging machining is usually confined to grinding or light, precision finishing rather than significant stock removal. Because the strength in aged maraging steel comes from fine, coherent intermetallic precipitates rather than a coarse carbide network, it doesn't cut like an equally hard conventional tool steel — it's less abrasive, but the process window narrows considerably. The cutting parameters below apply to the solution-annealed condition, which is how this material is most commonly machined before final heat treatment.