采用激光冲击强化（LSP）技术对TC4双相钛合金进行表面强化处理（冲击0~3次），研究了β相晶粒细化机理以及强化前后残余应力、表面硬度及疲劳强度的变化。结果表明：激光冲击强化过程中，β相晶粒内的位错首先通过滑移形成位错线，随着塑性变形加剧，位错不断堆积形成位错壁和位错胞，位错进一步运动后形成亚晶界，并通过动态再结晶实现晶粒细化；3次冲击强化后，合金的晶粒尺寸由原始板材的21.33 μm降至4.68 μm；随着激光冲击强化次数增加，合金表面的残余压应力、显微硬度及疲劳强度均增大。

Laser shock peening (LSP) technology was used to strengthen the surface of TC4 duplex titanium alloy (impact 0-3 times). The grain refinement mechanism of β phase and the changes of residual stress, surface hardness and fatigue strength before and after strengthening were studied. The results show that during the process of LSP, dislocations in the β phase grains firstly formed dislocation lines by slipping. As the plastic deformation intensified, dislocations piled up continuously to form dislocation walls and dislocation cells. After further movement of dislocations, sub grain boundaries were formed, and the grain refinement was achieved through dynamic recrystallization. After three times of impact strengthening, the grain size of the alloy was reduced from 21.33 μm of the original sheet to 4.68 μm. As the time of LSP increased, the residual compressive stress, microhardness and fatigue strength of the alloy surface increased.