Abstract
In order to protect industrial components, cobalt base alloys are applied as hardfacing material through welding techniques. A large number of papers have shown that controlling the chemical composition is a key point regarding the wear and corrosion resistance of coatings. This paper investigated the effect of bead overlapping on the microstructure and properties of CoCrWC alloy coatings. Mechanical properties were determined by hardness, sliding wear and microtensile tests. Bead overlapping reduces dilution during the previous bead melting, which in turn induces lower iron content. From the second bead on, an increase in the amount of interdendritic carbides and solid solution alloying was verified, accounting for the higher mechanical properties of the coatings.
Highlights
Surface engineering continuously seeks to protect industrial components in order to improve their service life, either with new alloys or advanced manufacturing processes
It is worth noting that bead overlapping promoted a reduction in the iron content, reducing the dilution of coatings
An investigation of the chemical distribution by Energy Dispersive Spectrometry (EDS) (Fig. 10) pointed out the main phases in the microstructure and confirmed the results obtained in the chemical composition, showing a similar tendency regarding the iron content punctually analyzed in the cobalt-rich solid solution matrix (Co-SS) (Table 5)
Summary
Surface engineering continuously seeks to protect industrial components in order to improve their service life, either with new alloys or advanced manufacturing processes. Nuclear power plants have reported the risk resulting from the conversion of cobalt wear debris into radioactive 60Co, and have demanded a reduction of wear rate. Another typical harsh environment is met in hot-dip galvanizing lines. Bushings and bearings are exposed to a complex degradation mechanism, which involves abrasive wear, high temperature and molten metal corrosion, reducing the service life of parts[1,2,3,4,5,6]. The carbide reinforced alloy system can be selected for its inherent high strength, wear and corrosion resistance and ability to retain hardness at elevated temperatures[7]. Its microstructure consists of hard carbide particles dispersed in a cobalt-rich solid solution matrix (Co-SS)[7,8].chemical composition considerably influences microstructure and, mechanical properties and resistance to abrasion, since it dictates the volume fraction of carbides[1,2,3,7,8]
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