Classic tempering steels like 42CrMo4 are widely chosen as a material for forged safety components with different cross sections. In the past, it has been shown that the fatigue life of these components can be increased, while reducing the development and manufacturing costs, if new material concepts are used. These materials achieve their final mechanical properties directly after forging, simply through air-cooling. Through the omission of the quenching and tempering procedure, energy can be saved which leads to decreased production costs and CO2-emissions.
It has been shown in the past that with microalloyed medium-Mn steels the above mentioned goals can be fulfilled. However, compared to the classic tempering steels these materials have decrease toughness values. The aim of our project is to modify the toughness and the durability of these steels through an optimization of the alloying concepts.
In order to deal with the problem of embrittlement in medium-Mn steels, labroratory melts were cast. The focus thereby was to prevent Mn-segregation to the former austenite grain boundaries and grain size control.
The microstructure and elemental distribution was characterized by LOM (light optical microscopy), SEM (scanning electron microscopy), EBSD (electron back scatter diffraction) and EDX (energy dispersive X-ray spectroscopy). The mechanical behavior of the different materials was tested by tensile and notch impact tests. The cyclic material behavior was characterized using incremental step tests, and the microstructure before and after the cyclic load were compared.