Abstract
This paper presents fracture characteristics and a fracture surface morphology of the laser track material at the surface of carbon steels. The surface of steels was heat-treated with CO₂ laser of the power of 1 and 2 kW at different speeds of the sample. The samples with laser track were impact-fractured at the temperatures 20, -20, and -196 °C. In the melt zone of the laser track the intercrystalline fracture mechanism was identified. In thermally affected zone where the martensitic transformation takes place, the fracture is prevalently intercrystalline and only rarely transcrystalline. The test temperature has no influence on the fracture characteristics.

Key words
fracture characteristics, fracture surface morphology, carbon steels, intercrystalline fracture mechanism

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