Mechanism of effect of rare earth oxides on high temperature corrosion resistance of weld metal
(1.湖南省长沙市中南大学信息科学与工程学院2.Laboratory of Titanium Alloys, Beijing Institute of Aeronautical Materials,Beijing 100095, China3.Institute of Welding Material, Taiyuan University of Technology, Taiyuan 030024, China)
Abstract: Through the addition of rare earth oxides into the coating of electrodes, the high temperature oxidation and sulphidation resistance of weld metal were studied. The transfer mechanism of rare earth oxides from coating to the welding pool and the physicochemical reaction during the process were analyzed. With the application of scanning electron microscope and energy spectrometer, the mechanism of weld metal corrosion in air and sulphur environment were studied. The result shows that the addition of rare earth oxides can improve the high temperature resistance of weld metal, especially in sulphidation environment. The electrodes in which La2O3 is added have better performance than the electrodes in which CeO2 is added. The existence form and distribution characteristic of rare earth are defined. It is believed that the marked effect of rare earth oxides in sulphur environment is related to the corrosion mechanism.
Key words: high temperature; oxidation; sulphidation; rare earth oxide; electrode coating; weld metal