Abstract
The structure and properties of laser track material result from the interaction bet-ween the laser beam and the metal surface. During the treatment a laser transformation hardening with or without surface melting occurs. In carbon steels the microstructure in the surface layer of the hardened zone is formed by twinned martensite and in the deeper zones also a low-carbon lath martensite occurs. The microhardness of martensite in the laser track is lower than that formed after quenching in water due to self-tempering. The large size of prior austenitic grain is a negatíve property of the laser track materiál. In the transformation hardened zóne there is a higher content of retained austenite than in materiál quenched in water.

Key words
12 060 steels, microhardness, martensite, mechanical properties, structure

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