Microstructure And Properties Of High Speed Laser Cladding Nickel Base Alloy Coating Of High Pressure Plunger

High-pressure plunger as one of the major parts of the fracturing pump,injection pump,the working environment is very bad,the Great Wall in the working process of the column surface and pump barrel friction lead to wear and tear,in serious sand production oil Wells or work in a large number of corrosive medium environment,the plunger surface will cause serious corrosion and wear,leading to the failure of plunger even scrapped.Therefore,it is necessary to prepare high hardness and wear resistance coating on the surface of high pressure plunger to change the service life of plunger.As a new surface strengthening technology,high speed laser cladding can produce high hardness and wear resistance coating,which has great advantages in metallurgical industry.In this paper,using high-speed laser cladding technique,high speed laser on 45#steel SD-Ni45 alloy powder was prepared,and explores the process parameters on the surface of the laser cladding layer formability and dilution rate,the effect of using optical microscope（OM）,scanning electron microscope（SEM）,X-ray spectrometer（EDS）,X-ray diffraction（XRD）,and other means to different cladding speed of high speed laser cladding layer microstructure observation and analysis on the structure and composition,and through the friction and wear experiments and electrochemical experiments of high speed laser cladding layer wear-resisting corrosion resistance are measured,The influence of different linear velocities on the microstructure of high speed laser cladding layer was studied,the correlation between microstructure and properties of the coating was established,the strengthening mechanism of the coating was revealed,and the microstructure and wear resistance of the coating prepared by conventional laser cladding technology were compared.The results show that in the process of high speed laser cladding,the surface formability of the cladding layer becomes better and better with the increase of the cladding speed and the change of the cladding speed when the cladding power and the powder feeding amount remain the same,and no cracks occur.The dilution rate goes down.When the control cladding speed and powder feeding amount are constant,the cladding power is changed.When the cladding power is too small or too large,the surface formability of the cladding layer is poor.With the increase of power,the crack cracking tendency decreases gradually,and the dilution rate increases continuously.When the cladding power and the cladding speed remain constant,the powder feeding amount is changed.When the powder feeding amount is too small,the surface of the cladding layer has more fish-scale ripple;when the powder feeding amount is too large,the surface cracks of the cladding layer increase continuously,the crack sensitivity increases,and the penetration crack appears.The dilution rate decreases with the increase of the powder feeding amount.In the process of high speed laser cladding,with the increase of cladding speed,the phase of high speed laser cladding layer is mainly composed ofγ-（Ni,Fe）,Cr₂₃C₆,Cr₇C₃,W₂C,WC and so on.No new phase is produced,but the intensity of the diffraction peak of the cladding layer increases continuously,and the diffraction peak shifts to the left.With the increase of cladding speed,the grain structure of the cladding layer is refined,the burning loss of Cr and W elements is decreased,and the"chrysanthemum"Cr-rich phase and the spherical Cr-rich and W-rich phase with fine particles appear in the cladding layer.There are also relatively complete Cr₃C₂ and WC phases in the cladding layer.8m/min cladding layer relative to 4m/min cladding layer hardness increased about 51HV_0.1,to reduce heat affected zone about 92microns,abrasion resistance by about 2 times,the wear mechanism of three kinds of cladding speed were mainly fatigue wear and oxidation wear,8m/min cladding layer relative to 4m/min cladding layer from the corrosion potential increased 74.3mv,the corrosion current density decreased 0.528μA/cm²,with the increase of cladding rate,high speed laser cladding layer reinforced corrosion resistance.Compared with the conventional laser cladding layer,the dilution rate of the high speed laser cladding layer is obviously reduced,the grain structure is obviously refined,the hardness is increased by about 20%,and the wear resistance is increased by about 1.7 times.The wear mechanism of high speed laser cladding layer is mainly fatigue wear,while the wear mechanism of conventional laser cladding layer is mainly abrasive wear and fatigue wear.