Volume 8, Issue 5 (May 2011)
Laser Cladding and Heat Treatment of Ni–Co–Mo Maraging Steel
The subject of this paper is a surface-integrity analysis of Ni–Co–Mo laser cladded maraging steel (EN 10027-2, W. No. 1.2799). Experiments were performed on 3.3 kW Nd:YAG laser system with coaxial injection of Ni–Co–Mo powder alloy that integrates various modes of laser beam guidance and different degrees of overlapping. The specimens were subsequently solution and precipitation annealed in order to examine a precipitation hardening of the newly formed material using the scanning electron microscopy (SEM) with a microprobe for energy-dispersive spectroscopy analysis, supported by microhardness tests. The residual stresses were determined by a hole-drilling method, using the integral method for residual stresses calculation. Favourable compressive residual stresses are generated in laser cladded layers due to a phase transformation from austenite to lath-martensite. The optimal selection of laser cladding process parameters enables efficient and cost-effective maintenance of damaged surfaces on the vital parts of die-casting tools, made from 1.2799 maraging steel.