L 605 is the same wrought cobalt-base superalloy published elsewhere in this reference library as Haynes 25 (also known as Stellite 25 and Udimet 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.

Correction: the prior version of this page carried a commented-out description calling L 605 "nickel-based" with "57.7% nickel" - the same reused boilerplate found across several unrelated cobalt-alloy pages in the old dataset - directly contradicted by L 605's real, textbook-documented composition (cobalt dominant, nickel only ~10%). The old page's own general-information table also listed a hardness of 80.0 HRB, while that same commented-out prose separately claimed "38 HRC" - two different values on two different hardness scales for the same page, another internal contradiction that has been discarded. For consistency, the composition table below matches the verified data already published on this site's Haynes 25 page, since L 605 and Haynes 25 are the same alloy under different trade names.

L 605 is a solid-solution-strengthened wrought cobalt alloy combining excellent high-temperature strength with good oxidation resistance to about 980°C (1800°F) 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.

As a wrought cobalt-base superalloy, L 605 is generally easier to machine than the cast Haynes-Stellite grades (HS 30, HS 31/X-40, HS 36) covered elsewhere in this library, but it remains more difficult than most nickel-base superalloys of comparable strength. 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.

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.

L 605 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 L 605 lacks the abrasive cast carbide structure of HS 30/31/36, moderately higher cutting speeds are achievable than for those cast grades, but the alloy still demands rigid setups and conservative feeds relative to typical nickel superalloys.