R-235 is a precipitation-hardening nickel-base superalloy standardized under SAE J467 as a "special-purpose superalloy" for high-temperature service. It is built on a nickel matrix (roughly 63% by weight) with substantial chromium (15%) for oxidation resistance, along with iron, molybdenum, titanium, and aluminum additions that combine solid-solution strengthening with age-hardening gamma-prime precipitation.

R-235 is essentially the wrought/bar counterpart of GMR-235, a cast nickel superalloy already documented in this reference library and historically used for precision-cast turbocharger wheels and small gas-turbine hot-section components. The two share the same core Ni-Cr-Fe-Mo-Ti-Al chemistry and the same SAE J467 lineage, so shops already familiar with GMR-235 machining behavior will find R-235 responds almost identically at the cutting edge.

Data note: Legacy supplier records for this grade listed aluminum at "20%," a figure inconsistent with any known Ni-Cr-Fe superalloy chemistry and almost certainly a decimal-placement error carried over from an earlier data-entry pass. Cross-checking against the published SAE J467 specification confirms the correct maximum aluminum content is 2.00%, which is the value used in the table below. Similarly, the legacy record's "AISI 686" cross-reference does not correspond to this alloy family — UNS N06686 is an unrelated corrosion-resistant Ni-Cr-Mo alloy — and has been replaced here with the verified SAE / GMR-235 cross-reference.

R-235 presents the standard set of nickel-superalloy machining challenges, though its moderate alloy content (as the lowest-chromium, lowest-cobalt member of this batch) keeps it somewhat more forgiving than fully cobalt-loaded grades. Thermal conductivity is low relative to steel, so heat generated at the shear zone concentrates at the cutting edge instead of evacuating in the chip, accelerating crater wear on unsuitable tooling.

Work hardening is the second major concern: any rubbing, dwell, or light cut lets the surface layer harden under mechanical and thermal stress, making the next pass noticeably tougher to cut. A consistent, adequate chip load — never allowed to trail off — is essential to stay ahead of the hardening front. The alloy also retains a large share of its room-temperature strength well into the red-heat range, so the speed-driven softening that helps machinability in carbon steel does not provide relief here; edge temperatures climb while mechanical loads stay high, which is what drives notch wear and edge chipping when speeds are pushed too far.

Nickel's chemical affinity for common tool substrates also promotes galling and built-up edge, tearing the finished surface if the edge is not kept sharp and properly honed. Rigid setups, positive-rake sharp carbide, and steady coolant delivery remain the standard countermeasures.