| Summary: | 碩士 === 國立臺灣師範大學 === 工業教育學系 === 93 === Abstract
The study to investigate the effect of welding parameters on the weldability of AZ magnesium alloys . A butt welding without filler metal of AZ31, AZ80 and dissimilar matel (AZ31-AZ80) joint by GTAW. It includes three parts. The first part was the semblance of weld, the second part was the microstructure observation, the third part was the mechanical properties of weldment.
From the result of Mg alloys by GTAW, the weld width and aspect ratio both increase with increasing input energy. Especially, the weld width were wider in AZ80 than AZ31 Mg alloy.
From the microstructure observation, the formation of larger grain with increasing input energy. However, the number of secondary phase increases with decreasing input energy.
Mechanical tests includes microhandness tests and tensile tests, the study results indicate that the mechanical properties of weldment decreases with increasing input energy. From the results of mechanical tests, the mechanical strength of AZ80 were higher than AZ31and dissimilar joint weldment. The brittle fracture surface was observed in all tensile tested specimens.
Keywords: Al-Zn magnesium alloy, wldability, dissimilar joint.
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