Research On The Microstructure And Performance Of Nickel-based Supperalloys Prepared By Laser Direct Deposition For Blisks

The aero-engine blisk is the preferred structure and development trend of high-thrusting engine in the future.It can simplify the structure of the leaf disc while reducing the weight of the engine,thus improving the aerodynamic efficiency and reliability of the engine.Currently,the preparation technology of the blisk requires a great breakthrough.The laser direct deposition is a new technology combining layer by layer addition and integral forming of material,which is suitable for the preparation of a new whole leaf disk.The laser direct deposition technology is expected to achieve the transition structure combining composition,organization and performance from the turbine disk to the blade.In this paper,Nickel-based superalloy powder of GH4169 for typical turbine disc and K417G for blade is regard as the basic material.Mix powder with different proportions is decreasing the content of GH4169 powder and increasing the content of K417G powder at 10%mixed component difference.Nine groups of mixed component samples by the laser direct deposition was studied.The phase,microstructure,composition,hardness and tensile properties at room temperature of the sedimentary layer were analysed and characterized by means of XRD,OM,SEM,hardness test,universal material testing machine.The trend of the change of the mixed samples during the transition from the turbine disk to the blade was preliminarily evaluated.In the optimized process parameters of 1800W laser power,5 mm/s laser scanning speed and the lap rate of 40%,a semiconductor laser was used to prepare eleven groups containing two basic material of laser direct deposition forming block of nickel base superalloy materials.The experimental results showed that the deposition layer has no defects,such as pores and cracks,and has good formability.In nickel-based superalloy by Laser direct deposition,the lower to middle part is composed of columnar crystal,and the top layer is fine cross dendrite.In mixed samples by Laser direct deposition,with the increase of K417G alloy content.The lattice constant of matrix y phase shows a downward trend from 0.36019nm(direct laser deposition of M10 sample)to 0.35850nm(M90 sample formed by laser direct deposition),the lattice constant of ?' phase increases gradually from 0.35692nm to 0.35753nm corresponding to the above component.The lattice mismatch of two phases is reduced from-0.912%to-0.217%.The main phases of GH4169 alloy are eutectic microstructure of y,laves,carbides and island(y+Laves)by laser direct deposition.The main phases of K417G alloy are eutectic microstructure of ?,?',carbide and dentate(?+Laves)by laser direct deposition.The main phases of nickel-based superalloy mixed component samples are eutectic microstructure of ?,?',laves and carbides.With the increase of K417G alloy content proportion,the morphology of the laves phase changes from the mass of(?+Laves)Eutectic to a lump,translucent strip and a significant decrease in the number.The carbides are distributed in a mixed and a short rod like distribution in a mixed material,with the increase of K417G alloy content proportion,carbides appear a tendency from rich Nb type to rich Ti type.The average microhardness of GH4169 alloy by Laser direct deposition technology is 223 HV.The yield strength and tensile strength are 415 MPa and 753 MPa,and the elongation is 32.81%.The average microhardness of K417G alloy is 410 HV.The yield strength and tensile strength are 743MP and 1026 MPa,and the elongation is 32.81%.In the prepared mixed component samples,when the proportion of K417G alloy is in the range of 20 wt.%to 80 wt.%,the microhardness and strength of the corresponding M80 mixed sample is the highest,which are 441 HV and 1172 MPa?...