Direct laser cladding of Ni-based alloy powder for industrial applications

摘要

Coatings of the nickel-based Metco 16C on the chromium steel substrate of a composition designed for the steam turbine blades are produced in a direct laser cladding process. A cw 1.2 kW CO2 laser stand equipped with a multi-stream nozzle mounted co-axially with the focusing optics is applied. Experiments are performed for the non-preheated as well as the preheated base material. Differences in microstructure, chemical composition, and in the cracking susceptibility between coatings produced on preheated (800-900K) and non-preheated substrates are analyzed by means of scanning electron microscopy (SEM) and the Energy Dispersive X-ray Spectroscopy (XEDS). Results indicate a significant improvement of the clad quality with the increase of preheating temperature. The presence of Fe in the coating is ascribed to migration from substrate due to preheating.