The story of CTS XHP begins in the 1990s when metallurgists at Carpenter Technology were looking to achieve what seemed like a balancing act: they wanted the supreme hardness found in tool steels like D2, yet also the stainless characteristics of steels like 440C. Back in 1994, a patent was granted for a steel called 440XH, the brainchild of Paul Novotny, Thomas McCaffrey, and Raymond Hemphill. Their experiments aimed to raise hardness beyond what 440C could offer while improving corrosion resistance relative to D2. These early trials involved casting and forging small, roughly 17‑pound ingots, with the team testing hardness across a range of austenitizing temperatures (between 1750 °F and 2000 °F), then subjecting samples to high humidity to rate rust resistance. Through trial and error, one variant stood out: alloy 89, which delivered both comparable corrosion resistance to 440C and significantly higher hardness.

At first, 440XH was produced conventionally, not as a powder‑metallurgy steel, which meant larger carbide formations and somewhat weaker toughness. But Carpenter didn’t stop there. Recognizing the limitations of the as‑forged version, they shifted to a powder‑metallurgy (PM) route. This allowed them to refine the carbide structure, eliminate elemental segregation, and ensure consistency from batch to batch, making the alloy much more reliable in real‑world applications. This shift toward PM helped transform 440XH into the steel we now know as CTS XHP.

CTS XHP’s big leap into mainstream production came when Cold Steel decided to roll it out across much of its catalog. Around 2015, they began phasing out AUS-8A, which had been a mainstay for years, and replacing it with CTS XHP in popular models such as the Recon 1. This was a significant step because it moved the steel out of the realm of limited runs and small-batch customs and placed it into the hands of a wide base of everyday knife users. The change was widely recognized as a performance upgrade, with reviewers and enthusiasts pointing to improved edge retention and cutting aggression, while sharpening remained within reach for anyone accustomed to maintaining modern stainless steels. Cold Steel often paired XHP with DLC coatings, further boosting its durability and wear resistance.

This period cemented CTS XHP as a steel that could compete directly with Crucible’s S30V and S35VN, two of the most popular stainless tool steels of the time. Independent testing confirmed that XHP could achieve edge retention comparable to those alloys while sometimes offering slightly higher attainable hardness. In terms of corrosion resistance, it remained closer to 440C than to high-molybdenum stainless steels, which meant it was plenty stainless for daily carry and outdoor use but not as resistant as something like Elmax or M390. For many users, though, the tradeoff was worth it because the steel sharpened cleanly and delivered a crisp, long-lasting edge.

In 2018, Cold Steel announced it was phasing out CTS XHP in favor of CPM S35VN, citing challenges in sourcing enough steel to support their production needs. The decision was not due to performance problems but purely supply-driven, and it underscored an important point about knife steels: no matter how well an alloy performs, it can only become widespread if supply chains can reliably support it. While this move reduced CTS XHP’s visibility in the mass market, it did not remove it from circulation entirely.

Since then, CTS XHP has continued to appear in knives from a variety of makers. Spyderco has used it in periodic Sprint Runs and exclusives, keeping it in front of dedicated collectors and steel enthusiasts. Custom makers and smaller brands also still turn to it, especially when they want a stainless blade that can take high hardness without sacrificing ease of sharpening.

Today, CTS XHP is seen as a steel that carved out its own niche. Born from a 1990s project to outdo 440C while matching the toughness of D2, refined into a powder metallurgy product, and proven by major brands in the 2010s, it still earns respect in the modern knife market. It might not dominate catalogs the way S35VN, M390, or MagnaCut does, but it continues to find its way into blades where its strengths can shine.