Enhancement of damage tolerance of 52100 bearing steel by influencing the static and dynamic cold working features due to defined stabilized retained austenite

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The aim of the planned research project is to develop a damage tolerant 52100 bearing steel (german steel grade 100Cr6). From a methodical point of view, a significant increase in local work hardening ability combined with high local stress resistance and good dimensional stability have to be implemented. The scientific hypothesis to reach this goal is a specific combination of alloy and heat treatment to adjust the retained austenite content, distribution and stability. Therefore the physical relationships in a technical material have to be understood and a depth knowledge on the underlying microstructural mechanisms has to be acquired. For this purpose the stabilizing mechanisms acting under cyclic stress and cyclic induced local transformation of retained austenite to martensite and their dependency on increased operating temperature have to be investigated. If the aim of the research project is reached, the identified materials variant has an enhanced damage tolerance compared to conventional bearing steels. The enhanced work hardening rate due to local phase transformation strengthens the matrix around e.g. crack tips and therewith avoids, inhibits and stops fracture. Simultaneously the tolerance of the material against internal defects increases, so that the cost intensive increase of material purity can be avoided.