| K417G nickel-based superalloy not only has the advantages of low density of K417 alloy,but also with its plasticity,high and medium temperature strength,excellent structural stability and excellent casting performance,it is suitable for making blades that work for a long time below 900 ℃ and other high temperature parts..At present,the application of this alloy in various types of engines is increasing.However,because K417 G nickel-base superalloy is greatly affected by heat input,it is easy to produce defects such as pores and thermal deformation when welding with ordinary welding processes,which seriously affects the performance of the welded joint.However,laser welding has the characteristics of fast welding speed,large welding depth,small thermal deformation,and large welding seam aspect ratio.It is very suitable for welding K417 G nickel-based superalloy.Studying the changes in the performance of K417 G alloy laser welding joints to optimize the laser welding process and improve the quality of the alloy welds will help guide the actual production and application of laser welding K417 G.A fiber laser processing system is used to conduct laser welding experiments on 4mm thick K417 G nickel-based superalloy.Using a single variable method,three laser process parameters(laser power,laser scanning speed,defocusing amount)are used to study the effect of three laser process parameters(laser power,laser scanning speed,defocus)on the formation of alloy welds.The structure and performance of the welded joints are tested and analyzed.The welding seam forming process is to grow columnar crystals from the weld fusion line.The growth direction is along the maximum temperature gradient perpendicular to the welding fusion line,and grows to the central area of the weld to form equiaxed crystals.The process parameters of laser welding(laser power,laser scanning speed,defocusing amount)have an important influence on the weld formation.The laser scanning speed increases,the weld penetration depth becomes smaller;the laser power increases,the weld penetration depth increases;the defocus amount increases,the weld penetration decreases,and the penetration width increases.During the welding process,the strengthening phase near the heat-affected zone of the K417 G alloy weld is dissolved or partially dissolved under the rapid action of the laser heat source.The mass fractions of the main constituent elements Ni and Cr do not change significantly.The C element as the carbide strengthening phase The atom moved to the weld area and the base metal area close to the heat-affected zone,causing its C element content to rise slightly.K417 G alloy weld microhardness results are distributed from the weld centerline area through the weld fusion line,heat-affected zone to the base metal area.The microhardness first decreases and then increases,the weld centerline area is the highest,and the weld fusion line And the heat-affected zone is the lowest.In addition,laser welding has an important influence on the process parameters on the corrosion resistance and thermal shock resistance of K417 G alloy welds.On the whole,under the process parameters of 20mm/s laser scanning speed,1500 W laser power,and +2mm defocusing amount,K417 G The overall performance of the alloy weld is the best. |
