Research On Mechanical Properties And Strengthening Mechanism Of GH3039 Superalloy By Laser Shock Treatment

Due to its excellent creep and strength characteristics at high temperature,superalloys are widely used in manufacturing hot end components of aero engines.With the increasing thrust of modern aero engine,the mechanical properties of high performance and lightweight structural parts are required to be improved.As a new type of surface strengthening technology,Laser shock peening(LSP)technology can effectively improve the service life of high-temperature alloy and has a very profound significance.In this paper,GH3039 superalloy was taken as the research object,and the surface morphology,microstructure and mechanical properties of laser treated superalloy were studied,so as to provide a basis for the application of laser impact enhancement technology in hot end components such as superalloy.The main research work and related conclusions can be presented as follows:The surface of GH3039 superalloy was treated with different laser energy by Procudo200 laser shot peening system made by LSPT company in U.S..The stress-strain curves of superalloy before and after LSP treatment were obtained by tensile test with MTS landmark 370.10 electro-hydraulic servo test system.The strain of superalloy in the process of drawing was collected synchronously by Aramis three-dimensional optical deformation strain measurement and analysis system,and the influence of different laser energy on the effect of laser shock strengthening was explored.The fracture morphology was observed by ∑IGMA500 scanning electron microscope(SEM).The results showed that the tensile properties of GH3039 superalloy increase with the increase of laser pulse energy,but the plasticity of superalloy decrease obviously.For example,when the laser pulse energy was 8J,the room temperature tensile strength of LSP treated superalloy was increased from 834.8 MPa to 923.2 MPa,increased by 10.6% and the elongation decreased from 27.6% to 17.2%,decreased by 37.7%.After LSP treatment,the surface strain of the superalloy was obviously lower than that of the original sample.There are equiaxed dimples on the fracture surface of LSP treated specimens,but the dimples are smaller and shallower,which is attributed to the work hardening of the surface of the superalloy caused by LSP treatment.The surface of GH3039 superalloy sheets were treated by LSP to study the effect of LSP on the fatigue life of the GH3039 superalloy.The experimental results indicated that after LSP treatment,the average surface hardness of samples was increased from 453.2HV to 498.5HV,and the average residual stress induced by LSP reached about-255.07 MPa at the sample surface.The average surface roughness was increased from 0.0346μm to 0.048μm.The grain size in the surface layer of sample was remarkable refined and reached the nanometer scale.Furthermore,the mean fatigue life was observed to be improved by 2.41 times after LSP.It was further verified by mathematical statistics that LSP treatment had a significant effect on the fatigue life of GH3039 superalloy.Finally,the increase in fatigue life of the LSP-treated GH3039 superalloy could be mainly attributed to the residual compressive stress and grain refinement.