Abstract
The addition of Rhenium up to 6% to Ni-Cr alloys can dramatically improve the corrosion and oxide resistance of deposited coatings at high operating temperatures. Ni-Cr+Re layers can be successfully produced using conventional powder metallurgy, high rate solidification (HRS), or magnetron sputtering methods. However, in industrial applications, high-performance deposition methods are needed, e.g., laser cladding. Laser cladding has several advantages, e.g., metallurgical bonding, narrow heat-affected zone (HAZ), low dilution, and slight thermal damage to the substrate. In this paper, a powder Ni-Cr composite with 1% (wt.) of Rhenium was produced, then deposited onto a steel substrate (16Mo3) by laser cladding to assess the micro and macrostructural properties of the obtained layers. Besides the macro and microscopic observations, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) microanalysis of the deposit and HAZ as well as microhardness measurements have been conducted. The microstructure observations revealed four subareas of HAZ gradually changing from the fusion line towards the base material. Maximum hardness occurred in the HAZ, mainly in areas closer to the clad/substrate interface, reaching up to 350–400 HV. No sudden changes in the composition of the deposit and the area of fusion line were observed.
Highlights
The surfaces of machine parts working at elevated temperatures in harsh corrosion and erosion environments are subjected to increasingly higher performance requirements, which occur in many areas of application, e.g., energy, aerospace [1], chemical, and other industries [2]
One of the widely used materials for surface layers resistant to difficult working conditions at high temperatures are Ni-Cr alloys. They have found wide application, among others, for working surfaces of turbine blades in aircraft engines [3]. Another broad area of application of these materials is boiler surface elements used in the power industry [4], for which the protective requirements, e.g., high-temperature corrosion [5]
Metals,the thedepth, depth,chemical chemicalcomposition, composition,microstructure, microstructure,and and associated properties of the alloyed zone depend on the suitable choice associated properties of the alloyed zone depend on the suitable choiceofoflaser lasertype typeand and processing processingparameters, parameters,i.e., i.e.,incident incidentpower powerororenergy, energy,beam beamdiameter, diameter,shape shapeororprofile, profile, interaction interactiontime, time,thickness, thickness,chemical chemicalcomposition compositionand andphysical physicalproperties propertieslike likeabsorption absorption coefficient, thermal conductivity, melting point and density of materials used coefficient, thermal conductivity, melting point and density of materials used[32]
Summary
The surfaces of machine parts working at elevated temperatures in harsh corrosion and erosion environments are subjected to increasingly higher performance requirements, which occur in many areas of application, e.g., energy, aerospace [1], chemical, and other industries [2]. One of the widely used materials for surface layers resistant to difficult working conditions at high temperatures are Ni-Cr alloys. They have found wide application, among others, for working surfaces of turbine blades in aircraft engines [3]. Another broad area of application of these materials is boiler surface elements used in the power industry [4], for which the protective requirements, e.g., high-temperature corrosion [5]. The effect of temperature on the oxidation behavior of binary Ni-Cr alloys in the CO2 gas atmosphere has been studied in [7] and it was shown that at 650 ◦ C, the oxidation rates were not significantly decreased until the alloy Cr content reached 30%
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