The graph illustrates the improved toughness of M2, as measured by the Izod unnotched impact test, that results from the use of lower-than-normal austenitizing temperatures. Numerous investigators have shown that the optimum means for attaining maximum toughness in high-speed steel is through reduced austenitizing temperatures rather than by full austenitizing and over-tempering to an equivalent hardness level.
Volume 4D, Heat Treating of Irons and Steels ⇒ Tool Steels -> Heat Treating of High-Speed Tool Steels ⇒ Recommended Heat-Treating Procedures
