Microstructure And Property Research Of Laser Deposition Repair GH4169 Alloy

GH4169 superalloy has been widely used in the fields of aerospace,nuclear power and petrochemical industry because of its excellent mechanical properties in high temperature environment,especially the thin-walled components made in high temperature alloy in the fields of aerospace.These components will generate error processing damage such as dimension deviation and milling grooves inevitably in the process of machining,and generate the damage such as crack,erosion and abrasion in the process of service.In this paper,aiming at surface damage specimen,the laser deposition repair(LDR)process is studied,the microstructure,tensile properties and tensile fracture of GH4169 alloy were studied in laser repair,laser repair under substrate preheating and heat treatment.The main results of the study are shown below:Aiming at the problem of surface damage repair of GH4169 alloy thin-walled components,the LDR research of different substrate thickness is done,the effect of repair specimen on the residual stress,microstructure and tensile properties of LDR GH4169 alloy have been investigated.The results show that,with the smaller substrate thickness,the residual stress is increased,the volume fraction of interdendritic Laves phase is larger,the tensile properties are decreased.The experimental results show that the substrate thickness has a significantly effect on the tensile properties and microstructure of surface damage repair specimen.Aiming at the problem of weakening performance of GH4169 alloy surface damage repair specimen,the substrate preheating research of different substrate thickness is done,the effect of substrate preheating on the residual stress,microstructure and tensile properties have been investigated.The results show that,LDR GH4169 alloy after the substrate is preheated to300?,the residual stress is reduced obviously.The Laves phase becomes thick,and it presents a granular fragmentation phenomenon.The tensile strength is reduced slightly,but the elongation rate increases above 60%.The experimental results indicate that substratepreheating is beneficial to improve the plasticity of LDR GH4169 alloy.Aiming at the problem of biggish residual stress in the process of LDR GH4169 alloy,low-power input of LDR GH4169 alloy have been studied The experimental results indicate that adopting 600 w low-power input to LDR damage specimen,the residual stress is less than1400 w high-power input of repair specimen,obtaining lesser heat affected zone.Aiming at the problem of decreasing tensile properties of LDR specimen,the research of local heat treatment and vacuum heat treatment is done.The results show that the average microhardness of repaired zone of local heat treatment specimen improve obviously after treatment,the average microhardness of repaired zone of vacuum heat treatment specimen increased,which is slightly more than that of local heat treatment.The dimple size of tensile fracture with two kinds of heat treatment methods varies slightly.It indicates that both local heat treatment and vacuum heat treatment can achieve the aim of improving tensile properties.