Microstructural aspects of laser dissimilar welds of hard metals to steels

Laser beam welding has been widely used in industry in the past decade. Recently, applications in dissimilar welds involving hard metals have been investigated. Hard metals are commonly used in tool manufacturing and this application requires joining to steel holders. The physical, structural, and mechanical properties of these materials pose several welding problems thus stimulating the application of laser welding. Research efforts have been mainly focused on developing procedures in order to achieve narrow fusion and heat affected zones with minimal distortions. Investigations on the weld microstructures and defect formation were also carried out. This paper presents an analysis of the influence of CO2 and Nd:yttrium-aluminum-garnet laser welding parameters on the microstructural aspects of the welds, discusses solidification microstructures and solid state transformations in dissimilar welds of carbon steels to hard metals, aiming at understanding the weldability of these materials. (C) 2004 Laser Institute of America.