마그네슘합금 압출판재의 마찰교반용접부 온도변화에 따른 용접부 특성 변화 연구

초록

The optimum temperature condition was obtained by analyzing the characteristics of the welds according to the temperature difference of the weld zone during friction stir welding of magnesium alloy. The welded condition was verified by applying the derived temperature condition to the hollow extruded members. As a result of temperature measurement of friction stir weld zone of magnesium alloy AZ61 extruded plate, the maximum temperature generation range was about 448℃-577℃, which was larger than 100℃ depending on the welding conditions. In addition, a method of confirming the overall temperature distribution of the welding specimen by deriving the emissivity value suitable for the magnesium alloy using the Thermo-graphic camera was proposed. When the maximum temperature of the weld zone is less than 474℃ defects in the weld zone due to lack of stirring were occurred, and when the temperature exceeds 577℃, oxidation defects in the weld zone were occurred. These defects led to a drop in the mechanical strength of the weld zone. On the other hand, when the maximum temperature range was about 493℃-515℃, defects did not occur in the weld zone. Compared to the base material, the maximum yield strength was about 84%, tensile strength was about 104%, and elongation rate was 99.5%.