AZ31 Magnesium Alloy Welded Joints Chemical Coating And Corrosion Studies

Magnesium alloy which has excellent features make magnesium alloysare widely used in electrical appliances, machinery, transportation and otherindustries and become a recognized green metal structure materials in today’sworld. In the process of long-term use, the emergence of magnesium alloycorrosive, softening and other issues, has restricted the further expansion ofapplication fields, various applications of magnesium alloy technology issuesand develop the existing potential performance has become a hot researchtopic. In order to solve the problems of corrosion of magnesium alloy, scholarshave conducted a lot of research, and put forward a variety of protectivemeasures, such as chemical conversion coating, anodizing, laser processing,the magnesium alloy chemical conversion film has the characteristics ofsimple process, low investment cost and wide application in practice. With thesituation in the different fields of application, magnesium alloy magnesiumalloy welded joints welded structure lead to material failure caused bycorrosion enough attention. Because of magnesium alloy under the effect ofthermal cycle in welding process, welding joint organization changed a lot indifferent areas. Traditional magnesium alloy corrosion protection technologyand mechanism are based on magnesium alloy as the research object, so thecorrosion protection of the traditional technology is not necessarily suitable formagnesium alloy welded joint, need further exploration.In this paper, using the scholars commonly used environmentallyfriendly magnesium alloy phosphating formula, with the weld microstructureof AZ31magnesium alloy samples as the research object, make suitablephosphating process. The film forming mechanism of welded joint is studiedby the film change of welded joint..The corrosion mechanism is studied by thefilm change of welded joint in sodium chloride solution.SEM results show thatthe film of the weld zone is dense and uniform.XRD results show that he filmwas an amorphous film layer.EDS results show that the phosphate film consists of Mn,P, Mg, O and other elements. The film electrode potential in theprocess is changing all the time.In the process of film forming corrosiondissolve of substrate is the first step. The aggradations of the phosphateconversion is the second step, thickness change of the film is the third step.The corrosion tests show that the corrosion resistance of phosphate layer areimproved obviously. The self-healing function of the film in the in sodiumchloride solution to improve the corrosion resistance plays a big role.