激光喷丸作用下TC4双相钛合金HCP结构位错组态及性能研究

Dislocation Patterns and Properties of HCP Structure in TC4 Dual-phase Titanium Alloy via Laser Shock Peening

对双相钛合金开展激光喷丸强化处理,研究密排六方(HCP)结构超高应变率塑性变形作用下位错组态演变规律及性能变化。结果表明:激光冲击波力学效应可以诱导材料表层生成残余压应力,促进晶粒细化,且随着喷丸次数的增加,晶粒细化效果越明显,残余压应力值和影响层深度越大。激光喷丸作用下,HCP结构位错组态演变规律可以描述为:对于原始试样(平均晶粒尺寸d=21.33μm),以位错和位错为主;单次强化(平均晶粒尺寸d=9.65μm)后,部分不稳定的位错分解成了位错和位错;多次强化(平均晶粒尺寸d=4.55μm)后,更多的滑移系被激活,主要为稳定的位错和位错。HCP结构的硬度和弹性模量均随着强化次数的增加而增大,但是增幅减弱。

The evolution of dislocation patterns and the properties of hexagonal close-packed(HCP) structure in TC4 dual-phase titanium alloy under ultra-high strain rate plastic deformation were studied via laser shot peening(LSP) treatment. The results show that, the compressive residual stress can be generated and the grains can be refined by the LSP treatment. Moreover, with the LSP times increasing, more finer grains, larger compressive residual stress, and the depth of LSP-induced compressive residual stress are generated. The evolution of dislocation patterns in the HCP structure subjected to LSP treatments can be described as follows. For the as-machined specimen(with an average grain size d=21.33 μm),dislocations anddislocations are dominant. While for the LSP-1 specimen(with an average grain size d=9.65 μm), parts of unstabledislocations are decomposed intodislocations anddislocations. After massive LSP treatments(with an average grain size d=4.55 μm), more slip systems are activated, anddislocations anddislocations are dominant eventually. In addition, Values of hardness and elastic modulus of HCP structure increase with the increase of strengthening times, but the increment decreases simultaneously.