|摘要: ||本研究分別以低頻(57,67Hz)、中頻(150,250Hz)、高頻(350,365,375,390Hz)三種不同的震動頻率範圍應用於AISI 304不銹鋼同步震動銲接。藉由光學顯微鏡觀察銲道顯微結構，並利用影像分析量測殘留δ-肥粒鐵含量，再以X-ray繞射分析探討晶體結構變化與量測殘留應力，其機械性質則以微小維氏硬度計與奈米壓痕分析。|
化，並且於共振頻(375Hz)時，晶粒細化效果最佳。殘留δ-肥粒鐵含量方面，同步震動銲接造成殘留δ-肥粒鐵含量下降與殘留δ-肥粒鐵的細化，且隨著振幅的提高，震動頻率為共振頻(375Hz)時，能得到最少殘留δ-肥粒鐵含量(4.07 %)。X-ray繞射的結果顯示，AISI 304不銹鋼在有震動與無震動銲接情形下，都是以γ(111) 優選方向生長。且經過震動後使得材料繞射峰的半高寬有明顯地增寬，其主要原因為晶粒細化所造成，且當震動頻率能量越高(共振頻)時效果最明顯。
The Study of AISI 304 stainless steel is focus on vibration welding under low, middle, and high frequencies with (57,67Hz), (150,250Hz), and (350,365,375,390Hz), respectively. Microstructure, residual δ-ferrite content, crystal structure, residual stress and mechanical properties of the weld bead have been investigated by using optical microscope (OM), X-ray diffraction (XRD), Vickers hardness tester and Nano-indentation, respectively.
The results showed that the refinement of grain size after vibration welding, especially in resonance frequency. With regard to the residual δ-ferrite content, it decreased with the amplitude of vibration increasing. It was noted that residual δ-ferrite content was the least 4.07 % in vibration welding with resonance frequency. From XRD results, (111) was appeared the preferred orientation of γphase during vibrationless and vibration welding. However, FWHM (Full Width at Half Maximum) of X-ray diffraction profile broadened after vibration welding owing to grain refined.
In addition, residual stress can be effectively reduced by vibration welding. The residual stress has decreased trend while the amplitude is increased. As a result, 137 MPa of residual stress can be obtained in resonance vibration welding.
As to the mechanical properties analysis, the hardness and Young's Modulus was enhanced in vibration welding with low and middle frequencies. In addition, the hardness has obvious raised about 7.6%, Young's Modulus increased from 170.2 to 196.5MPa while resonance frequency was applied.
Summarize the total results, resonance vibration welding possessed a less amount of residual δ-ferrite, lowest residual stress, and grain refinement weld bead which have better mechanical properties.