高能喷丸表层纳米化对纯钛旋转弯曲疲劳性能的影响

Influence of High-energy Peening Surface Nano-crystallization on Fatigue Life of Pure Titanium

采用高能喷丸方法使工业纯钛疲劳试样的表层实现纳米化,并进行了疲劳试验。结果表明,高能喷丸后其表层组织发生严重塑性变形并实现组织纳米化,是提高弯曲疲劳寿命的主要原因。扫描电子显微镜分析发现,疲劳裂纹源的位置主要呈现为表层和次表层两种情况。在相同应力水平下,疲劳裂纹源在次表层时疲劳寿命较长,而疲劳裂纹源在表面时疲劳寿命很短,相应的疲劳试样的表面损伤也比较严重。

Fatigue test was carried out for commercial pure titanium that have nano-crystallized in surface by high-energy shot peening. The result indicates that the improvement of the fatigue limit is due to the nano-crystallization and severe plastic deformation in the surface layer induced by high-energy shot peening. The observations of fracture surface under SEM found that fatigue cracks initiation area exists mostly in surface and in subsurface. In case of the fatigue cracks initiation area in surface, specimen exhibits longer fatigue life. In the other case, the surface damage of specimen by high-energy shot peening results in short fatigue life or instant break.