4. Molded tools

There is still regular production of cast tools with the same chemical composition as wrought grades. These products are of interest because of their economic advantages and the improved surface finish made possible by certain manufacturing processes (chill casting). High solidification speeds enable relatively fine skin structures to be obtained, with generally favorable orientations in relation to tool stresses. Segregation rates of alloying elements can be reduced by prolonged homogenization treatments at temperatures between 1,100 and 1,200°C, particularly in the case of hot tool steels with lower carbon content. For example, the segregation rates of alloying elements such as chromium and molybdenum can be reduced by 50% after 20 h at 1,150°C in the case of a relatively coarse equiaxed crystallization structure.

In the case of hot-work tool steels, and in particular...