M42

Technical Data

BS4659 BM42 is a cobalt high speed steel which achieves a high hardness with excellent cutting performance and good toughness. After heat treatment M42 has excellent wear resistance, M42 will achieve a high heat treated hardness of 68 to 70 Rockwell C.

Annealing: 
Annealed at 770 to 850°C. Soak thoroughly at this temperature and control furnace cool.  

Hardening:
For best results harden M42 in a vacuum or atmosphere furnace, or in a properly rectified salt bath. Pre heat throughly to 820 to 870°C, transfer to the high temperature salt bath or furnace. The exact hardening temperature to use will depend on the type of work being treated, but in general M42 components should be hardened from the range of 1160 to 1180°C in salt, or 1180 to 1190°C in atmosphere or vacuum furnaces. After a short hold at the hardening temperature, quench the M42 component without further soaking into salt at 540 to 595°C or warm oil. If salt quenched allow the M42 component to equalise at the bath temperature and then complete the quench in still air. The maximum temperature of the M42 component before tempering shoud be 65°C. Larger components should not be allowed to remain at room temperature without tempering.
Tempering: 
M42 components can be tempered between 510 to 595°C. For M42 high speed steel components a minimum tempering temperature of 540°C  is recommended to provide suitable relief to the hardening stresses. Triple tempering is recommended with a minimum of two hours at temperature per cycle. The M42 components should be cooled in still air to room temperature between tempering treatments.

BS4659 BM42 available in:-