Effect Of Y₂O₃ And Ti On Microstructure And Properties Of Laser Cladding 304L Stainless Steel Coatings

The traditional preparation method of nano-oxide dispersion strengthened steel is to dissolve oxides into the alloy matrix by mechanical alloying,and make them disperse,so as to improve the comprehensive properties of the material.However,traditional preparation methods still have many problems.For example,it is easy to produce pore,inclusion and an uneven distribution of nano-scale oxide.The traditional preparation has a long preparation cycle and a high price,which are not conducive to the production and application of ODS steel.In this paper,an ODS304L alloy coating was prepared on pure iron by laser cladding technology,and the quality of the laser cladding coating was improved by post-heat treatment process.The alloy powder is a composite alloy powder based on 304L stainless steel powder,which is prepared by ball milling with different content of Y2O3 and Ti powder.The phase and microstructure of the laser cladding ODS304L coating were analyzed by means of X-ray diffraction,optical microscopy,scanning electron microscopy and energy dispersive spectrometer.The gradient hardness of the cross-section of the coating was measured by vickers hardness tester,and the corrosion resistance of the coating was studied by electrochemical testing system.The results showed that[Y-Ti-O]strengthening phase was precipitated in the laser cladding ODS304L coating,and the[Y-Ti-O]strengthening phase was regular spherical and distributed uniformly in the matrix without obvious cluster phenomenon.The size of precipitated phase increased gradually from top to bottom of the laser cladding coating.When the addition of Y2O3powder was 1wt%and Ti powder is 0.3wt%,the maximum average hardness of laser cladding ODS304L coating is 280HV_0.2,and the corrosion resistance is the best.Compared with the laser cladding coating,the size of oxide dispersion phase in the laser cladding coating after subsequent heat treatment decreased,the compactness of the coating increased,the corrosion resistance improved but the microhardness decreased.When the addition of Y2O3 powder was 1wt%and Ti powder was 0.3wt%,the maximum average hardness of laser cladding ODS304L coating was 210HV0.2.Laser cladding combined with subsequent heat treatment process can produce ODS steel with[Y-Ti-O]strengthening phase,compact structure and good corrosion resistance,which provides a new method for the preparation of ODS steel.