| Magnesium alloys with many excellent properties are widely used in various fields,but their poor corrosion resistance seriously affects the service life and wider application of magnesium alloy.Laser shock peening(LSP)treatment as a new surface modification process can improve the corrosion resistance of metal materials.Therefore,the magnesium alloy is processed by LSP treatment to improve the corrosion resistance of magnesium alloy and extend its service life.Currently,the corrosion behavior of magnesium alloy subjected to LSP treatment has been studied,but the coverage layer,chloride ion concentration and immersion time on the corrosion resistance of magnesium alloy has not been studied systematically.Temperature is another important factor that affects the corrosion resistance of metallic materials.Lack of convenient control devices for precise control of corrosion temperature in electrochemical corrosion experiments has hindered researchers to study the influence of temperature on the corrosion resistance of metal materials,and it is not easy to reduce the effect of temperature on the experiment.The effects of the coverage layer,Cl~-concentration and immersion time on the corrosion resistance of AM50 magnesium alloy were studied in this paper,and the reasonable electrochemical corrosion experimental temperature control device also was designed.(1)In order to reduce the effect of temperature on the experimental results and facilitate the study of the effect of temperature on the corrosion resistance of metallic materials,a temperature control device for electrochemical corrosion testing is designed to control the temperature of the corrosion experiment accurately and constantly,which is convenient for the subsequent study of the effect of temperature on the corrosion resistance of magnesium alloys.The overall design of the temperature control device for electrochemical corrosion experiment was completed,which mainly includes the temperature control system and the electrochemical corrosion experiment.The Qt Creator software was used to design the man-machine interface,which controls the operation of the device,on the PC.And Keil software was used to complete the design of the control software for temperature control device.(2)The corrosion resistance of the AM50 magnesium alloy subjected to one,two and four coverage layers of LSP treatment in 3.5%.wt NaCl solution was studied.The influence of coverage layer on the corrosion behavior of AM50 magnesium alloy was analyzed.The results showed that massive laser shock treatment can induce residual compressive stress and grain refinement on the surface,which can obviously improve the stress corrosion resistance of AM50 magnesium alloy.As the coverage layer increases,the anti-stress corrosion resistance improves.Massive LSP treatment obviously increases the free-corrosion potential and the radius of the capacitive impedance loop,and decreases the free-corrosion current density,indicating that massive LSP treatment can improve the electrochemical corrosion performance of AM50 alloy.The electrochemical corrosion performance of AM50 alloy increases gradually with increasing coverage layer of massive LSP treatment.(3)The corrosion resistance of the AM50 magnesium alloy subjected to massive LSP treatment in 3.5%.wt,7%.wt and 14%.wt NaCl solution was studied.The influence of Cl~-concentration on the corrosion behavior of AM50 magnesium alloy was analyzed.The results showed that massive LSP treatment can improve the corrosion resistance of AM50magnesium alloy in the same concentration of NaCl solution when the chloride ion concentration is not higher than 14%.And no matter the massive LSP treatment or not,with the increase of Cl~-concentration,the corrosion resistance of AM50 magnesium alloy decreases accordingly.The improvement of massive LSP treatment on corrosion resistance of AM50magnesium alloy decrease with the increase of Cl~-concentration.(4)The corrosion resistance of the AM50 magnesium alloy subjected to massive LSP treatment in 3.5%.wt,7%.wt and 14%.wt NaCl solution for different immersion time was studied.The influence of immersion time on the corrosion behavior of AM50magnesium alloy was analyzed.The electrochemical corrosion of as-machined specimen was initiating and accelerating within the immersion time of 120 min.However,the LSPed specimens had a better electrochemical corrosion resistance within a short immersion time in the NaCl solution,and such beneficial effect was also suppressed when the immersion time exceeds a given value. |
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