Research On Process And Anti-wear And Corrosion Behavior Of Laser Cladded Cr-WC-Fe Composite Coatings

The coating prepared by laser cladding technology can significantly improve the corrosion resistance and wear resistance of petroleum equipment.Fe-based alloys have high wear and corrosion resistance,which prove to be important cladding materials for the preparation of anti-corrosion and wear resistance coatings.In this paper,Cr-WC-Fe composite coatings with excellent abrasion resistance were prepared on 15Cr Ni Mo steel by laser cladding technology for the following researches:(1)In order to obtain multi-channel overlapping Cr-WC-Fe composite coatings with good surface quality,a series of single-track composite coatings process tests were designed.The effects of laser power,scanning speed and powder feeding amount on the surface quality of single-track composite coatings were discussed.On the basis of several sets of single-track composite coatings process tests,the mapping model between the laser process parameters“P^?F^?V^?”and the characteristic morphology of single-track composite coatings with correlation coefficient R² greater than 0.92 was established,and the response relationship between the laser process parameters and the characteristic morphology of single-track composite coatings was clarified.Based on WOA-BP neural network,the characteristic morphologies of single composite coatings with different process parameters are mapped,and the maximum relative error is less than 5.5377%.In addition,the appropriate process parameters were determined to prepare multi-pass lap composite coatings.(2)The WC-Fe multi-channel lap coatings with 0wt.%WC,12wt.%WC,24wt.%WC,36wt.%WC,48wt.%WC and 60wt.%WC were prepared by selected process parameters.The surface quality,microstructure,phase composition,hardness and wear properties of WC-Fe composite coatings were studied.The results show that in order to ensure good surface quality,the content of WC in the composite coatings should not exceed 36wt.%.The structure and distribution of each cladding layer have common characteristics.The solidification form of the melt at the junction of the cladding layer and the substrate are planar crystals,the middle and lower parts of the coatings are columnar dendrites,and the surface of the coating is equiaxed dendrites.WC particles can refine the structure of the coatings,and the type and quantity of carbides in the coating,as well as the hardness increase with the increase of WC content,while the amount of wear shows a downward trend.Adhesive wear and abrasive wear occurred alternately in WC-Fe composite coatings,accompanied by three body abrasive wear.(3)The Cr-Fe composite coatings with 18%,24%and 30%Cr mass fraction were prepared under suitable process parameters.Experiments have confirmed that Cr element helps to improve the corrosion resistance of the composite coatings,and the passivation film on the surface of the coating is mainly composed of Fe O and Cr₂O₃.In acidic and neutral corrosive liquids,the corrosion resistance of composite coatings increases as the Cr content increasing in composite coatings,while in alkaline environment the opposite experimental phenomenon occurred.The corrosion resistance of Cr-Fe composite coatings in different electrolytes is ranked as follows:R_PH7>R_PH14>R_PH1.