Detection And Analysis On Corrosion Resistance Of 2Cr13 Stainless Steel After Laser Shock Peening In Different Corrosion Environments

2Cr13 stainless steel is a kind of high chromium martensitic stainless steel,which is widely used in industrial production because of the good performance.It also bears the interaction of corrosion environment and cyclic load,which makes it extremely vulnerable to corrosion fatigue failure and pitting corrosion.It is found that the fatigue life and corrosion resistance of materials are closely related to the microstructure and mechanical properties of materials.Laser Shock Peening(LSP)is a new surface strengthening method,which can effectively improve the fatigue and corrosion resistance of materials by inducing high compressive residual stress on the surface layer and nanocrystallizing the surface grains.The effects of different parameters of LSP and different corrosion environment on the corrosion resistance of 2Cr13 steel were investigated in this paper.The main research contents are as follows:(1)The effects of different coverage layers for LSP on the properties and microstructure of 2Cr13 martensitic stainless steel were studied.LSP induced high-density dislocations on the surface layer of 2Cr13 stainless steel,and a large number of nano-precipitates were produced at grain boundaries,which made the martensitic lathes refined into nanostructures,and the refinement degree of martensitic lathes increased as the coverage layer increased.In addition,LSP improved the microhardness value and surface roughness value of 2Cr13 stainless steel,and both values increased with increasing the coverage layers.The grain refinement induced by LSP provided the theoretical and experimental basis for improving the corrosion resistance of 2Cr13 stainless steel.(2)The effects of different energy for LSP on the corrosion fatigue behaviors of2Cr13 stainless steel in NaCl solution with different pH values were studied.The pH value of the corrosion solution was proportional to the corrosion fatigue life of the specimen.LSP induced high-amplitude compressive residual stress on the top surface of the specimen,which effectively inhibited the propagation of corrosion fatigue cracks.Compared with the as-machined specimen,the fatigue lifes of the S1,S2 and S3 specimen increased 15.08%,9.44%and 13.66%,respectively.The crack tip area was the effective influence area of LSP.When the pH value of NaCl solution was 3,the corrosion of fracture surface was the most serious,and hydrogen evolution corrosion occurred on the fracture surface.When the pH values of NaCl solution were7 and 11,the corrosion of fracture surface was reduced,oxygen absorption corrosion occurred on the fracture surface,and oxides of Fe and Cr were formed.(3)The effects of LSP with different coverage layers and energy on the electrochemical corrosion resistance of 2Cr13 stainless steel were studied.The electrochemical corrosion resistance of 2Cr13 steel was improved after LSP,and the corrosion resistance was further improved with increasing the impact energy and coverage layers of LSP.The number,depth and diameter of the corrosion pits on the surface layer of the specimen were obviously reduced after LSP by observing the surface corrosion morphology.The corrosion resistance of the as-machined and LSPed specimens decreased gradually with increasing the concentration of Cl~-in the NaCl solution.(4)A three-dimensional simulation model for fatigue specimen of 2Cr13 stainless steel was established,and the distribution of residual stress induced by LSP with different energy was obtained.The compressive residual stress was induced on the surface layer of the LSP model and distributed uniformly,which increased as the energy of LSP increased,indicating that the strengthening effect became stronger.At the same time,obvious plastic deformation occurred on the surface layer,which corresponded to the magnitude of the compressive residual stress.Combined with the stress measurement results,it was verified that the compressive residual stress induced by LSP can improve the corrosion resistance of 2Cr13 stainless steel.In conclusion,the research of this paper provided a theoretical and experimental basis for improving the corrosion resistance of 2Cr13 stainless steel after LSP treatment.