The influence of laser remelting on microstructural changes and hardness level of flame-sprayed NiCrBSi coatings with tungsten carbide addition

Abstract

The presented article describes the influence of the laser remelting process on microstructural changes, heat-affected zone size, dilution effect and hardness level of hard-facing Ni-based coatings based on NiCrBSi system with the addition of W2C\\WC carbide in the context of thermal diffusivity and specific heat value. This relationship is practically not described in the literature. Three commercial systems, Metco 15E, Metco 36C and customized Metco 15E + DURMAT® FTC, were deposited by flame-spraying on carbon steel with the following laser remelting treatment with different energetical variants. The total deposited in coatings energy value was used as a comparison criterion. The reflectance effect was also considered as a factor influencing the total energy transferred to the coatings. The dilution effect, heat-affected zone size, and hardness level in the context of microstructural changes caused by the laser remelting process in the context of thermal diffusivity were analyzed. It was revealed that the reflectance factor can be omitted as a negligible form point of view of total deposited energy in the coating. The thermal diffusivity of coating materials is similar, but the difference in HAZ and dilution effect is very significant. It can suggest that the thermal diffusivity is an important factor affecting microstructural changing in laser remelting process of flame sprayed NiCrBSi systems, especially when is considered together with specific heat related to presences of different fraction of tungsten carbide.