LASER METAL FORMING: PROCESS FUNDAMENTALS

Abstract

Laser metal fornling (LMF) is an innovative application for lasers with industrial potential for small series production, rapid prototyping, or repair engineering. It consists in the production of full strength metallic engineering components using a three-dimensional laser cladding process. Prototypes produced by LMF can be used to test the performance and reliability aspects of a particular design and must therefore have physical and mechanical properties similar to those of the mass produced part. The LMF technique can also be used to repair metallic parts and improve their life cycle behaviour. The fundamental aspects of this free forming technique were investigated to contribute to the physical understanding and to better control of the process. To this end, only simple geometrical parts have been produced. It was found that the dimensions, the shape, the shape instabilities, and the surface quality of the final components depend on the melt dynamics and on the kinetics of oxide formation at the surface of the alloy. Process conditions leading to the production of high quality parts have been determined for materials including steels, Stellite 6, IN 625 superalloy, and tin. The parts produced exhibit microstructures consisting of fine columnar dendritic grains without porosity and with mechanical properties equal to those of cast material.