Stellite 25 is the same wrought cobalt-base superalloy published elsewhere in this library as Haynes 25 and L-605, UNS R30605. It is cross-referenced to AMS 5537 (sheet/strip/plate), AMS 5759 (bar and forging stock), AMS 5796/5797 (welding wire/rod), and Werkstoff-Nr. 2.4964. Cobalt is the majority element at roughly 51%, alloyed with chromium, tungsten, and a moderate nickel addition - Kennametal's own current Stellite 25 datasheet confirms this same nominal chemistry (Cr 20%, W 15%, C 0.1%, balance Co with Ni/Fe/Si/Mo/Mn) and describes it as a "special low-carbon alloy with exceptional thermal fatigue resistance."

Unlike the numbered Stellite hardfacing grades (3, 20, 21, 23, 30) covered elsewhere in this library, Stellite 25/L-605 is a solid-solution-strengthened wrought alloy rather than a cast, carbide-network structure. It combines excellent high-temperature strength with good oxidation resistance to about 980degC (1800degF) for prolonged exposure, plus strong resistance to sulfidation and metal galling. Historic and current applications include gas turbine engine components (rings, blades, combustion chamber parts) and, notably, ball bearings and bearing races, where its cold-worked strength and wear resistance are used directly.

For consistency, the composition, machinability discussion, and cutting-speed table below match the verified data already published on this site's Haynes 25 and L 605 pages, since all three trade names refer to the identical UNS R30605 alloy.

As a wrought, solid-solution cobalt-base superalloy, Stellite 25/L-605 is generally easier to machine than the cast Stellite/Haynes-Stellite grades (21, 23, 30, 31/X-40) covered elsewhere in this library, because it lacks their carbide-network microstructure. It remains more difficult than most nickel-base superalloys of comparable strength, however. Thermal conductivity is very low - on the order of 10.5 W/m-K at room temperature - so heat generated in the cut concentrates at the tool-chip interface rather than dissipating into the chip, accelerating crater wear and edge deformation if speeds run too high.

Stellite 25/L-605 work-hardens very rapidly - Haynes International's own fabrication data notes that the alloy requires frequent intermediate anneals just to form cold, a strong signal of how aggressively it work-hardens under cutting forces as well. Any hesitation, rubbing, or light/inconsistent feed leaves a hardened layer that is significantly tougher to cut on the next pass, making steady, adequate chip load essential.

The alloy also retains strength at elevated temperature better than most nickel solid-solution alloys, so tool edges stay under heavy mechanical and thermal load throughout the cut. Its exceptional resistance to galling - a benefit in bearing and wear applications - is a liability at the cutting edge, promoting strong built-up edge and edge chipping unless tools are sharp, coated, and run with generous coolant. Because it lacks the abrasive cast carbide structure of the numbered hardfacing grades, moderately higher cutting speeds are achievable than for those grades, but rigid setups and conservative feeds relative to typical nickel superalloys are still required.