Stellite 151 is a cast cobalt-chromium-tungsten alloy positioned for combined wear and corrosion resistance rather than the extreme abrasion service of the highest-carbon Stellite grades. At roughly 65% cobalt, 20% chromium, 13% tungsten, and only about 0.5% carbon, it carries noticeably less carbide-forming carbon than Stellite 1, 12, or 19 - closer in that respect to the general-purpose grade Stellite 6 than to the extreme-wear grades. That lower carbide loading trades some abrasion resistance for better toughness and crack resistance, which suits it to cast valve and pump components that see both mechanical wear and exposure to corrosive or acidic process media.

Like Stellite 100, this alloy has been superseded in Kennametal Stellite's current published catalog and is not listed among the currently marketed Stellite grades, so this page relies on the store's existing reference record (independently corroborated for cobalt/nickel content against a third-party machinist materials database) rather than a live manufacturer datasheet. As a cast, moderate-carbide cobalt alloy, it belongs in the same broad wear-resistant category as the hardfacing Stellites in this library, but with a meaningfully different composition and use case than Stellite 1, 12, 19, or 100.

Stellite 151's lower carbon content (about 0.5%, versus 1.4-3.0% in Stellite 1, 12, and 19) gives it a noticeably less abrasive microstructure than the harder-wearing grades in this family, but it is still a cobalt-chromium alloy and still considerably harder to cut than plain steel or the high-temperature structural cobalt superalloys covered elsewhere in this library. Machinability is commonly rated in the same very-low tier as the rest of the cobalt-base superalloy group - poor thermal conductivity concentrates heat at the cutting edge, and the alloy work-hardens under light or interrupted cuts the same way its higher-carbon relatives do.

Because Stellite 151 is normally supplied as a casting for valve bodies, pump components, and similar corrosion/wear parts, most machining is finish or semi-finish work on cast blanks rather than heavy stock removal from bar. A positive, sharp cutting edge with adequate rigidity performs better here than the very robust, low-rake geometries needed for the higher-carbide hardfacing grades - Stellite 151's lower carbide fraction tolerates a somewhat more conventional approach, though still well short of what a plain carbon or low-alloy steel would allow.

Overall, expect Stellite 151 to machine somewhat more forgivingly than Stellite 1, 12, 19, or 100, but still notably more aggressively toward tool wear than S 816 or Stellite 188.