Control of defects during laser surface alloying

Abstract

Laser surface alloying is a new and promising technique for generating surface alloys having a wide range of favourable properties. The process involves altering the surfaces of inexpensive substrates by adding small quantities of alloying elements to a pool of molten metal produced by local melting using the intense heat of a laser. Certain defects such as cracks, porosity, surface roughness, compositional inhomogeneity, and excessive dilution have been observed during laser alloying (pulsed Nd : YAG laser) with chromium on mild steel, and with molybdenum and Ni–Mo on stain less steel. Specific deterioration in surface properties has been observed and discussed and the techniques utilised to control such defects have been outlined.