DIAGRAMS FOR LASER MATERIALS PROCESSING

An analytical heat flow model is used to identify dimensionless parameter groups which determine the temperature field produced in a material by a scanning laser beam. The groups are used to plot experimental data for metallic alloys on a processing diagram for a range of continuous CO2 laser treatments. Practical operating regions for each type of treatment are thus identified, which coincide with those predicted using the heat flow model. The model is extended in order to construct more detailed diagrams for transformation hardening, surface melting and keyhole welding, which quantify the depth of treatment. By using realistic estimates of certain poorly-known process variables, good agreement is observed between measured and predicted data. Methods for optimising processing parameters with respect to various criteria are presented for transformation hardening. The diagrams, which are constructed on a personal computer, are a useful tool for summarising current data, optimising practical processing parameters, and assessing the potential of novel laser treatments on new materials.