Chromium Substitution in High Speed Cutting Tools.

The chromium content of the cold work tool steel X155CrVMo121 (Thyrodur 2379) was reduced to about 10% and substituted by manganese in two steps. Although the alloy variations have no significant influence on the annealed microstructure they lead to a grain refining tendency in the hardened condition. Particularly the transformation behavior of the steels is influenced by the partial substitution of chromium. The increased manganese content stabilizes the austenite which causes a lower hardness in the as quenched state. Pearlite- and bainite-transformations are retarded and lowered in their temperature-range. The M//s-temperature is lowered as well as the A//C//1-temperatures. Chromium is partially substituted by manganese in the carbide composition which does not affect the amount and type of carbides. Among the mechanical and technological properties hardness, deformability, and wear resistance show indications of changes.