Influence of picosecond laser pulses on the microstructure of austenitic materials

We investigate samples of austenitic materials ?C stainless steel and iron-based superalloy ?C which are widely used at high temperatures and pressures. The samples were exposed to Nd³⁺:YAG laser pulses with a wavelength of 1064 nm and a pulse duration of 170 ps. We employ different pulse energies and number of pulses. The spots appearing after the laser irradiation were examined by optical and scanning electron microscopy and analyzed by energy-dispersive spectroscopy. We also perform Vickers microhardness tests. We discuss the microstructure changes caused by different energy and number of pulses in air and in a He-enriched atmosphere with the aim to determine optimum laser parameters in surface-treatment technology.