Tool steels

Given their chemical composition, with high carbon and alloying element contents, tool steels are mainly produced by the electrical industry, using ingot and consumable electrode remelting techniques. A significant proportion of grades are produced by powder metallurgy.

In fact, continuous casting is only practised for certain categories of steel that are close to mechanical engineering steels (silicon manganese steels, 102Cr6 bearing steels). Continuous casting trials for high-speed steels and alloyed tool steels were carried out in the 1960s and 1980s respectively, but were abandoned for reasons of cost and industrial reliability, despite some technical successes (e.g. high-speed steel milling cutters where the central part was eliminated by machining).

The detrimental influence of residual elements on the service properties of tool steels has led to the increasing use of special manufacturing processes such as vacuum or slag remelting. Prealloyed powder metallurgy was also introduced in this class of materials, notably high-speed steels and alloyed cold-work tool steels, in the early 1970s, with the joint development of hot isostatic compaction and hydrostatic extrusion.

The combined techniques of multidirectional forging and high-temperature annealing have enabled us to reduce the segregation rates of alloying elements in forged parts, with good isotropy of mechanical characteristics, aided by the use of numerical hot deformation calculation codes.

For further details on this subject, please consult the bibliographical references presented in the documentation section of this article.