ATS-34

ATS-34 is the Japanese twin of the American 154CM and was one of the most sought-after steels for high-end knives in the 1980s and 1990s. Here are the key facts:

Origin: ATS-34 is made by Hitachi Metals in Japan (renamed Proterial in 2023). Its composition is nearly identical to Crucible's American 154CM, which was originally developed for ball bearings in jet engines. This steel family became famous through legendary American knifemaker Bob Loveless, who was already using 154CM in the 1970s. When its quality slipped in the 1980s, Loveless switched to the Japanese ATS-34, and many custom knifemakers and manufacturers such as Benchmade followed. That made ATS-34 the premium steel of the knife world for about two decades.

Composition: ATS-34 consists of the following main elements:
Carbon (C): approx. 1.05%
Chromium (Cr): approx. 14.0%
Molybdenum (Mo): approx. 4.0%
Manganese (Mn): approx. 0.4%
Silicon (Si): approx. 0.35%

What stands out is the high molybdenum content of around 4%. It clearly sets ATS-34 apart from 440C and gives it a finer structure and better edge retention.

Hardness: typical range 58–61 HRC.

Edge Retention: somewhat better than 440C, but below D2 and clearly behind modern powder steels such as S30V or MagnaCut. In its day, that was considered top-tier.

Corrosion Resistance: good and fine for everyday use. However, ATS-34 is generally regarded as slightly less rust-resistant than 440C and falls well short of MagnaCut. It benefits from a little care in humid conditions.

Practical Takeaway: ATS-34 was the "super steel" of the 1990s, until the powder steel S30V replaced it as the premium standard in 2001. It sharpens fairly easily and takes a beautiful mirror polish, which made it popular with custom knifemakers. For collectors, it is chiefly interesting as the steel of the classic Loveless era and of many 1990s Benchmade models. It is less common today because many makers have moved to 154CM, which is once again produced to a high standard, or to its powder version, CPM-154.