Hardness Regulation of Fe-Based Amorphous Composite Coatings by Laser Remelting

Abstract

A Fe-based amorphous composite coating was deposited on a carbon steel substrate by arc spraying, and remelted with different laser energies by the Nd: YAG laser cladding system, in order to improve the mechanical properties of the coatings. The microstructure and microhardness of the composite coatings were investigated. The variation of harndness was measured as a function of the modified layer depth, which indicates that the laser remelting improves the bonding strength and hardness. Increasing the laser power, the quality of coating gets better, but the amorphous volume fraction decreases. It is obtained that the optimal laser electric current for the coating of 280 μm thickness is about 300 A, in which the remelted coating with medium energy densities has the highest average Vickers hardness of 741. Through the volume fraction change of the nanocrytals, the hardness of the composite coating is regulated by the laser power input, which amplified the application fields of the amorphous coatings.

Fe-Based Amorphous Composite Coating Prepared by Plasma Remelting

“…The high temperature gradient determines the directional solidified fine grain structure of the remelted layer. In the surface of the remelted area which possesses the maximum temperature gradient, no dendritic grains formed [11]. Compared with the dendrite layer of the remelted area, the numbers of cellular dendritic phases are greatly reduced and the microstructure becomes more diffused and refined, which are beneficial to the uniform distribution of the carbide and boride reinforcing ceramics.…”