Tool steel, process for producing parts of such steel and a steel part obtained in such a manner

摘要

The present invention relates to a tool steel with the following composition of individual elements: 0.8 to 1,5 percent by weight of carbon 5.0 to 14 percent by weight of chromium, 0.2 to 3 percent by weight of manganese, less than 5 percent by weight of nickel, less than 1 percent by weight of vanadium, less than 0.1 percent by weight of niobium, less than 2 percent by weight of silicon and aluminium, less than 1 percent by weight of copper, less than 0.3 percent by weight of sulfur, less than 0.1 percent by weight of calcium, less than 0.1 percent by weight of selenium, less than 0.1 percent by weight of tellurium, 1.0 to 4 percent by weight of Mo+W/2, 0.06 to 0.15 percent by weight of Ti+Zr/2, 0.004 to 0.02 percent by weight of nitrogen whereby the rest of the composition is comprised of iron and impurities resulting from the production process including 2.5.10e-4%e2 being less than or equal to (Ti+Zr/2) x N. The invention also relates to a process for producing a part made of the above-described steel wherein the production process is characterized by producing a liquid steel by melting a set of elements of the said composition with exception of titanium and/or zirconium and subsequently adding to the steel melt titanium and/or zirconium, whereby formation of local excessive concentrations of titanium and/or zirconium in the steel melt at any arbitrary moment being prevented. The liquid steel is then cast to obtain an ingot or a slab, the ingot or the slab is then subjected to plastic deformation by hot forming and subsequently a heat treatment in order to obtain the required part. The invention further relates to parts manufactured from the above-described steel or by the above-indicated process.