NAK 80 from International Mold Steel and Daido Steel is a pre-hardened mold steel (38-42 HRC) designed to be machined 10-15 percent faster than P20 steel. It does not contain sulfur, which enables it to achieve an optical polish that makes it suitable for lens-quality molds. It also is well-suited for EDM work.
According to the companies, the steel offers a uniform hardness and microstructure through to its interior, does not require stress-relieving, and is highly weldable. It is stocked in plate form ranging to 12.75" thick and in rounds from 0.512" to 9.921" in diameter.
Editor's PickHigh-Hardness Tool Steel Can Withstand High Temperatures
At 58-60 HRC, Bohler-Uddeholm’s Caldie is the toughest tool steel that the company carries, and that toughness is said to make it a suitable substitute for S7 applications such as smaller molds, core pins, cores and cavities.