MAR-M 905 is part of the same Martin Metals cast-superalloy naming family as MAR-M 302, MAR-M 322, MAR-M 509, and MAR-M 918, all developed for gas turbine hot-section hardware. Independent published data specific to MAR-M 905 is scarce, and this page has been rewritten to publish only the composition figures that can be treated as reliable rather than repeating a full data set inherited from an earlier, unverified source.

Data accuracy note: the equivalent-standards cross-reference previously listed for this page (AFNOR KC20N20Ta7) was found duplicated verbatim on the old record for the related alloy MAR-M 918, which strongly suggests the two pages' reference data were cross-contaminated at some point. That cross-reference has been removed from this page rather than republished. Similarly, a chromium figure of 0.5% previously listed for this material is inconsistent with every other alloy in this family (all of which carry roughly 20% chromium for oxidation resistance) and has been omitted as unreliable rather than republished. If you need a fully verified composition and equivalent-standard designation for MAR-M 905, consult a current mill certificate or the alloy manufacturer directly.

MAR-M 905 belongs to the same cast cobalt-nickel superalloy family used for turbine hot-section components as MAR-M 302, 322, 509, and 918, and general machining behavior can reasonably be extrapolated from that family even where the exact composition record is incomplete. Cast cobalt-base superalloys in this class retain hardness to very high temperatures - well beyond what steels or even many nickel alloys tolerate - so the cutting edge does not get the benefit of thermal softening at higher speeds the way it would on more conventional materials.

The cobalt-nickel matrix work-hardens readily under mechanical and thermal stress at the cutting edge, so consistent chip load without dwelling, rubbing, or light finishing passes is essential. If the alloy shares the carbide- or boride-strengthening approach common to the rest of the MAR-M family, expect embedded hard-phase particles in the cast microstructure to add an abrasive wear component on top of the base hot-hardness challenge.

Given the incomplete verified composition, treat this material with the same conservative approach used for its better-documented MAR-M relatives until it can be positively identified: low cutting speeds, sharp positive-rake ground carbide geometry, rigid workholding, and continuous coolant. Confirm actual hardness and microstructure with incoming material certification before committing to aggressive parameters.