The Microstructure of synchronal Vibratory Welding

• Main Authors: Kuo,Che-wei, 郭哲瑋
• Other Authors: Weite,Wu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/54954842637254301237

碩士 === 義守大學 === 材料科學與工程學系 === 89 === Abstract This research paper concerns the study of the change of metal structure, residual stress ,crystal structure, element composition, δ-Ferrite content and it’s shape under synchronous vibratory welding on 304 austenite stainless steel. The outcome shows that dendrite growth is restrained by synchronous vibration. The length of dendrite growth is 1000μm shorter than the non-vibratory specimen in this case. Concerning theδ-Ferrite content, it appears to have a little drop after synchronous vibratory welding is performed. Grain growth direction ofδ-Ferrite will be perpendicular to the weldment surface. Regarding crystal structure , the lattice constant of γ-phase has maximum value in non-vibratory condition. On the other hand, it will consistently to the increase in vibratory frequency. After 156Hz synchronous vibratory welding is applied, the specimen reaches maximum FWHM (Full Width at Half Maximum) and the minimum X-ray diffraction intensity. But no matter what the frequency is, the lattice constant has no difference in δ-phase. The lattice constant always remains at 2.88 Å. On the other hand, residual stress has the lowest value discovered from the distortion of weldment. But the residual stress measure by X-ray diffraction is 170Hz(resonance frequency) have the highest residual stress. Difference of the result is made by the property of the measure approach. Use exclusively the X-ray diffraction to measure the residual stress of γ-phase withoutδ-phase in this study. Finally, using EDS for point and area scan to find out the segregation of the weldment without any evidence shows there are segregations in the weldment.