Surface wear, material fatigue, and crack initiation in many mechanical components often originate at the surface, which makes surface properties crucial for their service life and operational reliability. For this reason, surface engineering plays an important role in improving the mechanical and tribological properties of structural materials. One of the modern methods for surface strengthening is laser surface hardening, which enables localized heating of the material, rapid cooling, and the formation of a hardened martensitic layer while preserving the mechanical properties of the core material. This master’s thesis presents an experimental analysis of microstructural changes and residual stresses in laser surface hardening of steels C45 and 42CrMo4. The experimental part includes laser hardening using an Nd:YAG laser system under different process parameters, where laser power, beam defocus, and the use of absorber were varied. After processing, metallographic microstructure analyses, microhardness measurements, and residual stress determination using X-ray diffraction were performed. The results show the formation of a martensitic hardened layer, increased microhardness, and a significant influence of process parameters on the hardened layer geometry and residual stress state.
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