Cryogenic Treatment Az31 Magnesium Alloy Tig Welded Joint Research On The Effects Of Corrosion Resistance

Magnesium alloy has the unique advantages of high strength、light weightand can be easily recovered, has become widely accepted, compared withtraditional engineering materials, it has positive prospects for the application，However, corrosion problems has been an urgent need to solve the magnesiumalloy can be widely applied or not. To solve the problem of corrosion resistanceof magnesium alloy (especially in an atmosphere of Cl-ions corrosion resistance)is very important. Magnesium alloy welding prone to a number of weldingdefects, these deficiencies will result in the corrosion resistance of welded jointscan be worse than the corrosion resistance of magnesium alloy. So, we try toimprove the defects of the magnesium alloy welded joints by cryogenictreatment process, in order to improve the corrosion resistance of the connector.In this paper, AZ31magnesium alloy TIG welding joints are studied toimprove the corrosion resistance of welded joints of magnesium alloy in NaClsolution. Based on the predecessors of magnesium in NaCl neutral solutioncorrosion mechanism research achievements, by corrosion weight loss methodof the comparative test, explore different deep cryogenic treatment holding timeof process parameters on the impact of the corrosion resistance of welded joints,by Super depth of field metallographic microscope、X-ray diffraction (XRD)、Electrochemical workstation and other experimental methods of observation andanalysis of the organizational structure of the alloy before and after deepcryogenic treatment and corrosion, we can be obtained from the test results, Thecorrosion resistance of magnesium alloy after cryogenic treatment can generallybe improved，after a period of corrosion in media concentration were3.5%and5%NaCl solution,the deep cryogenic processing time observed for6h and4h,respectively to improve the alloy corrosion resistance of the most advantageous.This phenomenon is mainly due to deep cryogenic treatment increased thecontent of the second phase of the magnesium alloy, and in another hand, it alsograin refinement and homogenization of magnesium alloys. Grain refinementcan improve the corrosion resistance of magnesium alloy, However, the β phasein the magnesium alloy on the corrosive impact is more complex, when its content is less, reducing the corrosion of magnesium alloy, more content will bewith α phase form Micro-galvanic and accelerate the corrosion of magnesiumalloy.