Effect of Laser Power and Substrate on the Hastelloy C276^TM Coatings Features Deposited by Laser Cladding

Abstract

Laser power influences the range of dilution with the substrate and thus, the microstructure and properties of the coatings. This work evaluated the effect of laser power on the dilution, microstructure, hardness and wear behavior of Hastelloy C276^TM alloy coatings deposited on AISI 304L stainless steel and GGG40 ductile iron. The microstructure was comprised of γ (Ni-FCC) dendrites and molybdenum-rich interdendritic regions containing carbides. The coatings showed similar second phase nature and fraction and equivalent hardness and wear behavior for the lowest laser power condition. Otherwise, higher power on 304L induced to a lower fraction of blocky-like M₂₃C₆/MC carbides; whilst on GGG40 led to a higher fraction of a predominantly lamellar M₆C type carbide. Largely diluted coatings on ductile iron entailed differences in the strengthening mechanisms which led to higher hardness and lower wear rate. Moreover, wear tracks showed surface oxidation which in turn negatively influenced the performance of specimens with low dilution on both substrates. On the other way, with high dilution, this feature was only observed on stainless steel.

Keywords
: Laser Cladding; Hastelloy C276^TM; Dilution; Microstructure; Hardness; Wear Behavior; AISI 304L stainless steel; GGG40 ductile iron