Laser direct writing of Co-superalloy lines for micro-fabrication applications

Abstract

Co-superalloy lines were deposited on stainless steel by a direct laser writing technique: laser micro-cladding by lateral powder injection. With the aim of producing small strips as thin and narrow as possible, the mean size of the powder used was 8 μm. Using such fine particles makes conventional powder feeders useless, due to the formation of agglomerates unable to be feed. Therefore a new powder feeder, here described, was designed, constructed and tested. A processing parameters map was established, identifying the working window for laser micro-cladding. The new power feeder and a high brightness, good beam quality fiber laser allowed producing fine lines just 14 μm wide and 7.2 μm thick. Microstructure and mechanical properties, in terms of Hardness and Elastic Modulus, were evaluated confirming that the fine strips maintain the main characteristics of the hardfacing alloy. Potential applications include micro-part fabrication and repairing such as micro-moulds, and production of 3D parts at sub-millimetre scales.