Machined Surface Integrity For Iron-Based Superalloy In High Speed Milling

Iron-based superalloys occupy an extremely important position in the field of superalloys and are widely used in the manufacture of hot end components,such as aerospace turbine engines and industrial gas turbines.Machined surface integrity plays an important role in service performance such as wear performance,corrosion resistance and fatigue resistance of components.In this paper,based on the surface properties of the iron-based superalloy GH2132,studied its machinability and surface integrity,mainly studied laws and influencing factors of the surface roughness and plastic deformation,surface metamorphic layer and microstructure,surface work hardening,the surface residual,which provides a theoretical basis for the efficient and high quality process of iron-based superalloys.First,studying the machinability of iron-based superalloys.Studying the influence of cutting parameters and tool materials on chip deformation,and revealed the mechanism of sawtooth chip formation.Through the comparison of cutting force,cutting temperature and tool life during the cutting process of AISI4340 steel,which shows that GH2132 has large cutting force,high cutting temperature and short tool life.It is more difficult to cut than AISI4340 and has poor processing quality stability.Therefore,systematic research on the surface integrity of machining is particularly important.Secondly,studying the surface roughness and plastic deformation of iron-base superalloy in milling.Explored the influence of cutting parameters on the surface roughness of GH2132,and reveales the influence of tool wear on the surface roughness of the machine.The results show that the factors that have a great influence on the surface roughness of the machine are f_z and a_p.The surface plastic deformation depth of GH2132 is26~55?m,and the plastic deformation depth decreases with the increases of v_c and a_e,and increaseing with the increases of f_z and a_p.The depth of plastic deformation of carbide AlTiN coated tools when cutting GH2132 is larger than that of carbide TiN/TiCN/TiAlN coated tools.The surface plastic strain is between 1.5 and 3.5,and the plastic strain increases with the increase of v_c,f_z and a_p,and is less affected by a_e.Thirdly,studying the surface metamorphic layer and microstructure of iron-based superalloy in milling.The surface metamorphic layer and microstructure of GH2132 are analyzed by means of EBSD and SEM.The results show that there are dislocations and twins in the microstructure of GH2132.The twins can promote the formation of metamorphic layers.The increase of v_c,f_z and a_p and the flank wear of the tool promotes the increase of the thickness of the metamorphic layer,the increase of a_e causes the thickness of the metamorphic layer to decrease.Finally,studying the surface hardening and residual stress of iron-based superalloy in milling.The surface hardening degree is 121.4%~145.7%when the carbide TiN/TiCN/TiAlN coated tool cutting the GH2132,and hardened layer depth is 73~100?m.The surface hardening degree is 119.4.%~150.6%when the carbide AlTiN coated tool cutting the GH2132,and hardened layer depth is 70~105?m.The residual stress mainly appears as tensile stress in the cutting and feeding directions.In the cutting direction,the stress is 170~660MPa;In the feed direction,the stress is-40~750MPa.Through the above research,it is found that TiN/TiCN/TiAlN coated tools are more suitable for cutting GH2132.When v_c=50~100 m/min,f_z=0.06~0.08 mm/z,a_p=0.2~0.3 mm,a_e=4~5 mm,the surface roughness,plastic deformation,work hardening of GH2132 are small,surface tensile stress is controlled,and can be obtain high surface quality.