Cladding of Ni-Cr-B-Si coatings with a high power diode laser

Laser surface cladding is a well recognised technique to obtain wear and corrosion resistance coatings, or for repairing damaged parts. Recently, the use of high power diode laser (HPDL) has undergone rapid growth for materials processing. The present work describes the process for obtaining two boride-containing nickel-based hardfacing alloy coatings, primarily composed of Ni-Cr-B-Si on carbon steel using a HPDL. After laser treatment the microstructure is composed of a matrix of gamma-Ni with different intermetallics depending on the initial composition of the powder. For the alloy with lower concentration of alloying elements, X-ray diffraction indicates the presence of nickel (Ni3Fe, Ni3Si,), boron (B4C, CrB) and chromium (Cr3Si) intermetallics. On the other hand, for the alloy with higher amount of C, B and Cr, the analysis revealed the presence of Ni3B together with lesser proportions of Ni3Fe and Ni3Si and the presence of chromium carbides Cr23C6 and (Fe-Ni)(23)C-6. (C) 2002 Elsevier Science B.V. All rights reserved.