A user commented in a live stream asking, “What materials are recommended for pre-hardened steel with a hardness of HRC 40?”
There are two main types of pre-hardened steel with a hardness of HRC 40: NAK80 and FDAC.
NAK80 is a time-hardening, pre-hardened plastic mold steel with a composition of 10Ni3MnCuAl and a hardness of HRC 40. Due to the addition of copper and aluminum, it offers excellent machinability and can be easily polished to a mirror finish. Compared to plastic mold steels such as P20 and 718H, it features higher hardness, better machinability, and superior polishing results, making it an excellent choice for plastic molds.
FDAC is a pre-hardened, free-cutting hot-work die steel with a hardness of HRC 40–44. Due to the addition of sulfur, it offers excellent machinability and eliminates the need for heat treatment typically required for hot-work die steels, thereby saving time and costs in mold production. It is generally used for rapid die-casting molds and can also be used for components such as sliders and inserts in die-casting molds; of course, it is also suitable for plastic molds.
These two grades are among the most well-known; other steel mills also produce grades with similar properties, though their performance and applications are largely comparable.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.