Design, Development and Characterization of high-alloyed steels

High-alloyed steels can be divided into the two groups of corrosion-resistant and tool steels, whereby the latter can be subdivided into cold work tool steels, hot work tool steels and high speed steels. Accordingly, there is a very broad field of applications of these steel groups, which ranges for example from household goods via plastic mould steels to forging dies, mills and drillers for machining. The alloy design, especially the carbon content, is essential for fulfilling the required mechanical properties such as wear resistant, toughness or creep resistance.

The aim of the research group is to reveal the structure-property relationships and the establishment of a deep understanding of the microstructure of these high-alloyed steels in order to lay the foundations for optimizations and new product developments. This should allow more efficient solution as well as reveal new fields of application.

In the field of high-alloyed tool steels, a method for the determination of the thermo-mechanical fatigue strength was evaluated, which is now successfully used for the testing of steels. This property is connected with the microstructure of dual hardening steels, which are used as plastic mould steels. Therefore, the precipitates and carbides are characterized by atom probe tomography. An exemplary measurement is shown in the figure below.

Atom probe tomography of a dual hardening steel with a concentration profile of a selected cylinder volume. The purple-coloured areas correspond the V enriched carbides, the green areas to intermetallic NiAl precipitate and the orange areas to Cu particles.