Research Of Grain Refinement And Corrosion Resistence Strengthening Of Laser Shock Processing On GH2036 Alloy

The iron-alloy GH2036 as the important material widely used in the production of turbine disks and fasteners of the aviation turbine jet engine. The performance of GH2036 alloy in long time high temperature service will declined, even caused accidents. So it is necessary to strengthen the mechanical properties and corrosion resistance of GH2036 alloy under the service condition of high temperature. LSP as a brand new surface modification technology which could improves the mechanical properties of metal effectively by high strain rate dynamic shock wave generated by laser shock processing and extend service life.In this paper, GH2036 alloy as the research object, the feasibility of laser shock to alloy strengthening processing is verified from two aspects: the macroscopic mechanical properties and the microstructure, and make analysis to its strengthening mechanism. The main work and conclusions of this paper are as follows:Firstly, the plastic deformation response process caused by laser plasma shock wave act on the surface of the material was analyzed. The effects of material and experimental environment on the impact of the laser shock process were analyzed. and the experimental parameters of laser shock GH2036 alloy through theoretical analysis and calculation were determined.Secondly, under the condition of LSP, the micro-hardness, surface topography, roughness and residual compressive stress were analyzed and concluded that Laser hardening mechanism of GH2036 alloy including precipitated phase strengthening, dislocation strengthening and fine grain strengthening. The interaction between precipitates and dislocations constitutes the dislocation strengtheningand the grain refinement model of laser shock GH2036 alloy was established. Low density dislocations are random distributed in original grains pile-up beginning in the initial deformation, which was induced by the concentration of stress. Then, dislocationss were formed to dislocation cells and dislocation tangles and another structures. Sub-grain boundary with a small angle and orientation divides coarse grains into sub-grains, which was transformed by dislocations. When the dislocation proliferation rate and lost rate balance, the grain refinement is accomplished.Finally, the effect of laser shock on the hot corrosion and electrochemical corrosion of GH2036 alloy were analyzed. During the macroscopic and microscopic point of view, the effect of laser shock on the corrosion resistance of GH2036 alloy was proved, the model for the formation of oxide scale and corrosion pits was established and the reason was theoretically analyzed. Research results show the residual compressive stress inhibited the emergence and development of corrosion products of spalling and cracking, prevent corrosion further intensified; laser shock effect of precipitated phase after the increase in the number and the microstructure changes of the surface structure of alloy is tightly fixed, reduce corrosion and to improve the corrosion resistance.