Maraging C200 is the entry-strength grade in the 18% nickel maraging steel family, and its name is literally a contraction of "martensite" and "aging" — the two-step process that gives these alloys their unusual property combination. On cooling from solution-annealing temperature, the very low carbon, nickel-cobalt-molybdenum chemistry transforms into a soft, ductile martensite rather than the hard, brittle martensite typical of conventional carbon-hardened steels. That soft martensitic condition is easy to machine and cold-form. A subsequent aging treatment at a moderate temperature then precipitates fine intermetallic compounds throughout that martensite matrix, raising strength dramatically without the toughness penalty that usually comes with through-hardening a carbon steel.

The "200" in the designation refers to the alloy's approximate minimum yield strength in ksi once fully aged — roughly 200,000 psi, or about 1,380 MPa. C200 is the lowest-strength, highest-toughness member of the cobalt-bearing C-series maraging grades, making it a common choice where high strength-to-weight ratio and dimensional stability through heat treatment matter more than reaching the absolute highest strength in the family — aerospace structural fittings, tooling components, and precision shafts among them.

Maraging steels have a split machinability personality that depends entirely on which side of the aging treatment the material is on. In the solution-annealed (unaged) condition — roughly 28-32 HRC — the soft, low-carbon martensite machines about as easily as a mild alloy steel: cutting forces are moderate, chip formation is manageable, and tool life is good with standard carbide grades. Most bar and plate stock is supplied and rough-machined in this condition specifically because it's the easiest stage to remove material, before the part goes through its final aging cycle to reach full strength.

Once aged, C200 jumps to roughly 48-50 HRC, and machinability changes considerably: cutting forces rise, tool wear accelerates, and finish-machining after aging is normally limited to grinding or light, precision cuts rather than heavy stock removal. Because there's no free carbide network forming during aging — the strengthening comes from fine, coherent intermetallic precipitates rather than large abrasive carbides — aged maraging steel doesn't behave quite like an equally hard tool steel; it still cuts in a relatively controlled, non-abrasive way, but at a much narrower process window than the annealed condition. The cutting data below reflects the solution-annealed, pre-aging condition, which is how this material is most commonly rough-machined.