The transformation hardening of steel surfaces by laser beams—I. Hypo-eutectoid steels

Abstract Surfaces can be treated with a scanning laser beam to modify their properties. The beam subjects the near-surface to a thermal cycle with an amplitude and shape which depends on the process variables: the beam size, energy, scan rate and on whether the laser is pulse or continuous, and the chemistry and metallurgy of the steel. Approximate solutions to the equations of heat flow are combined with kinetic models to predict the near-surface structure and hardness of plain carbon steels after laser treatment. The results are assembled into diagrams which show immediately the combination of process variables for a desired surface structure and the associated hardness profile.