激光冲击强化对TC17钛合金模拟叶片疲劳极限的影响

The effects of laser shock processing on the fatigue limit of TC17 alloy simulated blades

通过振动疲劳试验探究了激光冲击强化(LSP)对带根部倒圆的TC17钛合金叶片一阶弯曲疲劳极限的影响,结合疲劳断口、组织观察和残余应力测试等方法分析了激光冲击强化提高叶片疲劳极限的强化机制。结果表明,激光冲击强化对TC17钛合金叶片的一阶弯曲振动频率无影响,但显著提高了叶片的疲劳极限(约8%)。冲击强化后叶片的金相组织无显著变化,但表层晶粒组织明显细化,并在距离材料表面50μm的深度范围内形成剧烈塑性变形区,材料表面产生了不小于466 MPa的残余压应力。晶粒细化和残余压应力是叶片疲劳极限提高的直接原因。

The effects of laser shock processing(LSP)on the first order vibration fatigue limit of TC17 titanium alloy blades with fillets were studied by vibration fatigue test. Combining with fracture analysis, microstructure and residual stress testing, the strengthening mechanism of LSP for improving blade fatigue strength was analyzed. The fatigue test results show that compared with untreated specimens, the vibration frequency of the specimens treated by LSP has no change, but the fatigue strength has been significantly improved by about 8%. The metallographic structure of blades has no obvious change after LSP, but the surface grain structure has been refined and severe plastic deformation was formed in a depth of 50 μm from the surface. The residual compressive stress on the surface is greater than 466 MPa. Grain refinement and residual pressure are direct reasons for the improvement of blade fatigue limit.