Effects Of WC Content And Morphology On Microstructure And Properties Of Laser Cladding Layer Of Nickel Base Alloy

With the rapid development of China's industry,pump and valve products in the high temperature,high pressure,high load and corrosive medium and other harsh environment work more and more,which on the pump and valve products key parts of the surface of the wear resistance and corrosion resistance of higher requirements,researchers are also committed to exploring and trying new processes and technologies to innovate and upgrade existing products in order to design and develop products with higher reliability and longer service life.Based on the surface properties enhancement of key parts of pump and valve products,the composite cladding layer of Ni50 and WC on the surface of stainless steel by laser cladding with semiconductor laser is mainly studied to study the effects of WC content and morphology on the microstructure and properties of ni-based alloy cladding layer,to explore the appropriate ratio of WC and Ni50 and the effects of WC on the properties strengthening mechanism of ni-based alloy cladding layer,and the laser cladding layer preparation and service life test were carried out on the surface of the ball of ball valve.The main research work and conclusions are as follows:1?The effects of laser power and scanning speed on the molding performance of cladding layer were studied.By analyzing the macroscopic morphology,mechanical properties and crack sensitivity of the cladding layer,the laser cladding process parameters were optimized,and the appropriate process parameters were determined as follows:laser power of1.5kW,scanning speed of 2mm/s,spot size of 4×4mm,and powder feeding capacity of11g/min.2?The effects of nickel-coated WC content on the microstructure,microstructure,microhardness,wear resistance and corrosion resistance of nickel alloy cladding were studied.The results show that the bottom of Ni50 cladding layer is columnar crystal and dendritic crystal,and white carbide hard phase is diffused among dendrites.With the increase of nickel-coated WC,the columnar crystal at the bottom of the cladding layer gradually disappeared,the white carbide increased,the structure gradually refined,the dendritic gradually increased,and the growth direction tended to be disordered.The main phases of Ni50 cladding layer are?-?Ni,Fe?,Fe₇Ni₃,M₂₃C₆,etc.When nickel-coated WC was added,the main phases of cladding layer changed,mainly FeNi₃,Fe₇Ni₃,Fe₂W,etc.,while austenite?-?Ni,Fe?decreased,and intermetallic compounds FeNi₃ and Fe₂W were generated in situ.The microhardness of the cladding layer increases with the increase of the amount of nickel-coated WC.The friction coefficient of the cladding layer first decreases and then increases,while the wear volume first decreases and then increases.The cladding layer with 30%nickel-coated WC has the lowest friction coefficient,the smallest wear volume and the best wear resistance.Corrosion resistance of cladding layer increases first and then decreases.3?The morphology,WC particle distribution,microstructure and properties of nickel alloy cladding with different spherical WC contents were studied and analyzed.Studies have shown that the addition of spherical WC has a significant effect on the phase of nickel-based cladding layer.Compared with the phase of pure nickel-based cladding layer,the addition of FeNi₃,Fe₂W,WC,W₂C and other phases are added.The addition of WC particles can inhibit the formation of?-?Ni,Fe?phase of face-centered cubic structure,and promote the increase of intermetallic compounds FeNi₃ and Fe₂W.After the spherical WC particles were added into the cladding layer,the dendritic structure of the cladding layer was refined,and the hard phase underwent a series of morphological changes from long strip,dendritic to block.With the increase of spherical WC particle content,the microhardness of cladding layer increased obviously;With the exception of Ni50/10%WC cladding layer,the wear volume of other cladding layer decreases and the wear resistance increases.The corrosion resistance of Ni50/20%WC and Ni50/40%WC cladding is relatively good.4?Through the comprehensive analysis of the properties index such as the macroscopic morphology,crack sensitivity,phase,microstructure,microhardness,wear resistance,corrosion resistance,etc.,of the nickel-based WC enhanced composite cladding layer,when the addition amounts of nickel-coated WC and spherical WC are 30%and 20%respectively,the crack sensitivity of cladding layer is lower and the wear resistance and corrosion resistance are better.And the laser cladding layer was successfully prepared on the surface of the ball of ball valve.The service life of ball valve products can be effectively extended by testing.