We study the laser-induced plume created during steel welding. The plume emission is measured with a spectrograph and a photodiodes array detector. We study the evolution of temperature and electron density for several welding parameters. Temperature and density calculations are based on the observation of line intensities and shapes. The other part of this study presents briefly a theoretical model which allows calculating the densities of each component of a complex plasma; like the one of stainless steel. These calculations yield the absorption of the laser energy in the plume.