Study Of The Dynamic Compression Mechanical Behavior Of Laser Solid Formed GH4169 Superalloy

For its high temperature strength,excellent fatigue,durability and creep properties,excellent processing and welding performance,GH4169 superalloy is applied widly in the Aviation,aerospace,nuclear power and other important areas of national defense.Laser solid forming(LSF)is an advanced material manufacturing technology for preparing metal components and parts with complex configuration,and for the purpose of manufacturing with no dies,quickly,fully-dense and near-net shaping.In the past two decades,LSF has developed rapidly and applied widly in metal manufacture.This paper stuied the dynamic compression behavior of GH4169 superalloy experimentally and theoretically at the range of strain rate of 0.001/s~5000/s and temperature of 298K~1273K,in consideration of the initial defects produced in laser solide forming particularly.The main research contents are as follows:1.Firstly,four different LSF GH4169 superally samples were prepared with four groups of manufacturing parameters.Then,all the samples were heat-treated by direct-aging process and standard heat-treat process.Finally,the micro-structure and initial defects of all the smples with different manufacturing parameters or heat-treat conditions were observed and analysed by metallographic microscope and scanning electron microscope.2.The quasi-static and dynamic compression properties of all the LSF GH4169 superalloy samples were tested by electronic universal testing meshine and split Hopkinson pression bar respectively.It was found that the yield strength of LSF GH4169 superalloy showed a negative linear correlation of the first arm spacing of the micro-structure.The as-deposited and direct-aging LSF GH4169 superalloy appeared the anisotropy of comprassion properties,and the flow stress in X-direction(vertical deposition direction)was higher than Z-direction(along the deposition direction).While the anisotropy was eliminated by the standard heat-treat process.3.For it was abnormal that the flow stress of direct-aging LSF GH4169 superally first increase and then decrease with the temperature in a certain range,a physical concepts based constitutive model and the normal distribution were employed to describe the thermomechanical response of direct-aging LSF GH4169 superally.And the predicted results by the model were coincident approximatelly with the experimental results.4.The deformation,flaw and fracture appearances of sample of LSF GH4169 superalloy after compression were observed by metallographic microscope and scanning electron microscope.It was found that the compression cracks inited and propagated along the dendritic walls in quasi-static loading,while the dynaic loading produced transcrystalline cracking.In addition,the liquation cracking along the dendritic walls would aggravate the damage of the samples,and the gas pores would lead to the initation of cracks,the change of the evtension path of cracks and global damage pf samples.All the initial defects decreased the dynamic strength and shock resistance of LSF GH4169 superalloy.