Defect Elimination Techinque by Simultaneous Vibration Wlding

• Main Author: 賴銘祥
• Other Authors: 吳威德
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/76526010547335278789

碩士 === 義守大學 === 材料科學與工程研究所 === 86 === 　　Simultaneous vibration during welding was employed in this study. The weldment microstructure, chemical compositions, distortion, cracking and hardness were discussed. 　　Simultaneous vibration improves the welding cracking and distortion. The best results were shown in subresonant frequency. Simultaneous vibration also got the different microstructure of weld bead. It changed heat flow of solidification condition and grain orientation in the weld pool. The microstructure altered from the columnar dendritic to the equaxied dendritic mode. Analysis the weldment under various frequencies by X-ray diffraction, the 0Hz and 156Hz specimen had the same results. The cracks presented the hot cracking characteristic and it was ductility-dip crack (DTR). Solute precipitation and welding thermal stress are main factors lead weldment to fractrue. 　　The less welding distortion, the best result was found in subresonant frequency. however it can''t eliminate all distortion. The content of □-ferrite was decreased on weld bead s vibration applied.