Investigation of the Laser Material Interaction Regimes during Thermal and Compositional Superposition in Laser Surface Improvement

摘要

The objectives of the research are to (1) understand the reactions occurring within the indexed and surrounding regions as a result of the thermal and compositional cycling experienced during the formation of a laser surface modified layer, and (2) to evaluate the process kinetics, solidification and growth morphologies based on thermodynamic and heat conduction considerations. In order to accomplish these objectives, the laser surfacing process was divided into three significant categories. These are (1) the alloyed surface region and the phase reactions within that surface, (2) the grain growth/solid state transformation and tempered regions and the transformations within those regions, and (3) the thermal temporal history occurring during processing as determined both experimentally and computationally. Processing parameters for all of the trials are given in Table I. compositions of the base alloys used are given in Table II. In all cases, a Nd:YAG fiber optically delivered laser was used.