Study On Perfomance Optimizing Of Laser Cladding Fe-Cr-C System Alloy Coatings

3Cr13 stainless steel material has a unique corrosion resistance and a high hardness value,and has a wide range of applications in the tool field.However,the lack of natural of the component design has limited the application in high quality tools.And it is difficult to meet people's requirements for high-end use of tools.The use of laser cladding technology to prepare alloy coatings with high hardness,wear resistance,corrosion resistance and high bonding strength on the surface can effectively solve the problem.Of course,the choice of cladding powder material is important.In this paper,which is based on the existing powder system design concept,considering the problem of matching the high hardness value and corrosion resistance of the coating.At the same time,the concept of Fe-Cr-C alloy powder material with soluble second phase powder strengthening coating is proposed.The alloy coating is prepared according to the process parameters obtained by a large number of process tests and orthogonal optimization experiments,and the microstructure and properties of the alloy coating are systematically studied.Moreover,the cladding layer is also modified by heat treatment and addition of rare earth oxides,in order to improve the structure of the cladding layer,and obtain a cladding coating having excellent comprehensive properties such as high hardness and good corrosion resistance.Through research and analysis,the following conclusions are obtained:1.The Fe-Cr-C alloy coating was prepared by surface powder cladding on 3Cr13by synchronous powder feeding laser cladding technology.Then analyzing its microstructure,interface strength,hardness and corrosion resistance of the cladding layer.The results show that the sample breaks at the corresponding load of 5.1580 kN without the phenomenon of falling off the cladding layer,which proves that the cladding layer and the matrix material achieve excellent metallurgical bonding effect.The cladding layer is densely organized,and the defects such as pores and slag inclusions are significantly reduced.The cladding layer structure is intragranular martensite+retained austenite structure,and the grain boundary is a grid-like alloy carbide eutectic structure.And the average hardness value reached 628 HV₁,and the surface area hardness value was 668 HV₁,which was significantly higher than the matrix 451 HV₁ hardness value.However,the carbon content of the cladding layer is increased due to the presence of the soluble second phase powder.During the non-equilibrium solidification process,segregation of corrosion-resistant Cr elements occurs.The resultant of chromium-rich carbides between the dendrites results in a Cr-depleted matrix,which reduces the corrosion resistance of the cladding layer.2.In order to overcome the shortcomings of high residual stress cracking of the cladding layer and improve the corrosion resistance of the cladding layer,the subsequent heat treatment modification of the cladding layer is studied.And analyzed the effect of different holding time on the microstructure,hardness value and corrosion resistance of the cladding layer.The results show that the base structure of the cladding layer is slat+fine needle martensite,and the carbides on the dendrites are transformed from long rods into short rods and granules which are intermittently rounded.Microhardness is significantly improved after heat treatment Its maximum hardness value appeared at 1050?for 30min?average microhardness value 711 HV₁?,an increase of 83 HV₁ relative to the unheated cladding layer sample.Corrosion analysis showed that the self-corrosion potential,self-corrosion current density and pitting potential of the coating were improved compared with the original coating after heat treatment.The corrosion resistance of the cladding layer reaches the optimum value at30min retention time,the corrosion potential,pitting potential is the largest,and the self-corrosion current density is the smallest.It can be seen that the subsequent heat treatment has a positive effect on the hardness value and corrosion resistance of the cladding layer,and is an effective measure for the modification of the cladding layer.3.The method of adding different content of rare earth Y₂O₃ in Fe-Cr-C iron-based powder material is to study its influence on the microstructure,hardness and corrosion resistance of the cladding layer,and analyze the mechanism of action of rare earthY₂O_3.The results show that the addition of rare earth Y₂O₃ can improve the microstructure of the cladding layer,eliminate defects such as pores and inclusions.Its intergranular structure changes from rod and lamellar to short rod-like,granular,and the uniformity of the cladding layer increases,which shows that the hardness value of different regions of the cladding layer fluctuates.The addition of rare earth Y₂O₃ has a positive effect on the improvement of the corrosion resistance of the cladding layer.The addition of rare earth reduces the self-corrosion current density,improves the self-corrosion potential,and improves the corrosion resistance of the material.When the rare earth content is 3%,the pitting potential increases,and the corrosion resistance of the cladding layer is optimal.