Abstract
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 C276TM 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.
Highlights
Different coating technologies have been adopted as a way to form protective layers at the surface of industrial components
Hastelloy C276TM stands out for its high amount of molybdenum, which leads to the highest resistance to pitting corrosion
Some authors observed a significant increase in the mechanical properties of the coatings
Summary
Different coating technologies have been adopted as a way to form protective layers at the surface of industrial components. Beyond wear resistance under adhesion or abrasion, corrosion can take place sometimes farther, creating aggressive and complex degradation mechanisms In this context, iron, as well as cobalt and nickel-base alloys, are often selected[1]. Hastelloy C276TM stands out for its high amount of molybdenum, which leads to the highest resistance to pitting corrosion Furthermost, it presents high strength even without heat treatment because of tungsten and molybdenum act as solid solution hardeners[2]. Taking into account these elements are strong carbide formers, the second phase fraction may be altered due to the alloy dilution with the substrate during deposition. The above-mentioned works highlight the importance of material selection for both clad and substrate, once it usually helps to predict coatings microstructure and properties
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