The microstructural variation of fatigued nano-precipitated steel after heat treatment

• Main Authors: Chieh-Ning Yen, 顏介寗
• Other Authors: Shing-Hoa Wang
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/57470511153689864544

碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 99 === Arrayed nano-precipitated TiC has been obtained in ferrite matrix after thermal treatment. The grain size of interphase nano-precipitated Ti-microalloyed steel is not affected by fatigue deformation. Therefore, strengthening of the ferrite is attributed to nano-precipitates. The array of interphase nano-precipitation remains only at the shortest life cycles. The strengthening mechanism of nano interphase precipitated steel is caused by dislocation bowing. The elongated cell structure of dislocations was developed in the ferrite matrix at a strain amplitude of 1.2% with a strain rate of 10-4 s-1 due to the wavy-type dislocation. The grain orientation after fatigue is rotated toward the preferential {101}α orientation. A higher strain amplitude or lower strain rate results in an advantageous percentage of low angle grain misorientation.