Evolution of microstructure and properties in laser cladding of a Ni-Cr-B-Si hardfacing alloy

Abstract

Ni-Cr-B-Si coatings are used in many industrial applications in order to improve wear and/or corrosion properties. These coatings have traditionally been deposited by thermal spray techniques but the laser cladding process is also being increasingly employed to produce Ni-Cr-B-Si coatings with superior functional properties. In this research, the microstructural evolutions and the phase formations in the laser cladding of a Ni-Cr-B-Si alloy and their effects on the hardness of the clad layer are discussed. Results of this study show various types of boride and carbide phases can form in each track of the clad layer. These changes demonstrate the potential for tuning the properties of these coating by controlling the processing conditions.

Laser power and scanning speed influence on the microstructure, hardness, and slurry erosion performance of Colmonoy-5 claddings

“…31 A similar study reported that the floret-shaped particles are eutectics consisting of Cr 2 B and Ni. 15 It was also stated that three types of Cr-borides can be formed namely, Cr 2 B, CrB, and Cr 5 B 3 wherein the formation of CrB occurs directly from the melt, while Cr 5 B 3 may form by the peritectic reaction of CrB and the melt or directly from the melt. 15 Another work involving the TEM examination of precipitates reported the formation of Cr 7 C 3 carbide and borides namely, Cr 2 B and CrB besides Ni 3 Si silicide in c-Ni matrix.…”

“…15 It was also stated that three types of Cr-borides can be formed namely, Cr 2 B, CrB, and Cr 5 B 3 wherein the formation of CrB occurs directly from the melt, while Cr 5 B 3 may form by the peritectic reaction of CrB and the melt or directly from the melt. 15 Another work involving the TEM examination of precipitates reported the formation of Cr 7 C 3 carbide and borides namely, Cr 2 B and CrB besides Ni 3 Si silicide in c-Ni matrix. 18 Thus, these results show that variation in the laser power had a significant influence on the precipitation behavior of Colmonoy-5 clads keeping in view that all other process parameters were kept unchanged.…”

“…14 The application of laser cladding has increased significantly due to the development of high power lasers leading to the commercial use of laser-based surface modification processes. 15 Due to widespread industrial applications of cladding for surface modification, repair, and refurbishing purposes, extensive work has been reported in the literature for different processes and alloy compositions. Das et al 16 studied the role of dilution on the microstructure and wear performance of NiCr hardfaced deposits and reported that wear resistance decreased with an increase in the level of dilution from the base material.…”

“…Similarly, Hemmati et al 21 highlighted the role of controlling the dilution level on the microstructural evolution and properties of Ni-based coatings. In another study 15 focused on microstructural evolution and phase formations in Ni-Cr-B-Si alloy laser clads, it was reported that despite similar chemical composition and cladding parameters, different types of microstructures could be obtained in the clads.…”

Analysis of tribotechnical characteristics of self-fluxing coating under rolling and sliding at non-stationary loading

“…Несмотря на повы-шенный интерес к таким покрытиям, многие вопро-сы, связанные с изучением их формирования, влияния структурно-фазовых изменений исходных материалов на физико-механические свойства покрытий, в том числе и сопротивление усталости системы «покрытие-основа», остаются нерешенными [5]. Проведенные исследования самофлюсующихся сплавов Ni-Cr-B-Si с высоким со-держанием Cr и B показали, что для них характерно формирование различных типов микроструктур, зави-сящих от скоростей охлаждения и температуры [6].…”