Study On Composition And Technology Of Laser Cladding Ni60 Powder

Ni60 powder has the advantages of high hardness and corrosion resistance,and plays an important role in surface modification of metal materials.However,laser cladding of Ni60 powder is prone to defects such as porosity and cracks,especially in the laser cladding repair of large-area and large-volume parts,which makes it almost difficult for the material to be used in laser cladding repair.Therefore,by analyzing the cracking mechanism of laser cladding of Ni60 powder,the Ni60 powder mixed with elementary substance,alloyed Ni60 powder and alloy mixed powder was studied in order to obtain metal coatings with higher hardness and better corrosion resistance.Firstly,the Ni60 powder mixed with elementary substance was used for laser cladding.The burning loss of C and B in the cladding layer is 70%and 90%.adding refined grain B and Y elements into the powder,to explore its effect on the structure and properties of the cladding layer,and analyze the reasons for the low hardness of the cladding layer.The results show that with the increase of B content,the dilution rate of cladding layer decreases,the grain refines and the maximum hardness reaches280HV;Y can refine grains,purify grain boundaries and enhance the compactness of the cladding layer,thus increasing the microhardness of the cladding layer;B and Y increase the hardness of laser cladding layer,but the microhardness of laser cladding layer with mixed Ni60 powder can only reach 300 HV.Secondly,the alloyed Ni60 powder was used for laser cladding.B,Y,and V were added to the powder to refine the grain elements,and their effects on the microstructure and properties of the cladding layer were discussed.The results show that the burning loss of C and B is only 1%and 5%respectively in the laser cladding layer of alloyed Ni60.The main phases in the cladding layer are gamma-Ni solid solution,CrB,M₂₃C₆,M₇C₃,Fe₂B,Ni₃B,FeNi₃ and Fe₁₆Ni;With the increasing of B and Y elements,the microstructure of the cladding layer is refined,and the hardness of the cladding layer increases in varying degrees,but it still cracks;The hardness of the cladding layer decreases with the addition of V element.There is no crack in the1.5%V cladding layer,and the hardness is 568 HV.Finally,the Ni60 powder mixed elementary substance and alloyed Ni60 powder was used for laser cladding.The results show that as the alloying powder in the mixed powder increases,the microstructure of the cladding layer refines and the hardness of the cladding layer increases;When the percentage of the alloyed powder exceeds60%,cracks occur in the cladding layer;The scanning speed for experiments is optimized,and 60%alloy elemental mixed powder cladding layer hardness can reach390HV.Cladding layer thickness is 4.7mm,and cracks do not appear.The corrosion resistance is better than that of alloyed Ni60;Adding refined grain elements and strengthening phases into the mixed powder can be used for laser cladding repair of large area and large volume parts.