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应用Nd:YAG高功率激光器对TC6钛合金试样进行了激光喷丸,对部分强化试样623K真空保温10h。应用原子力显微镜(AFM)、扫描电镜(SEM)、电子背散射电镜(EBSD)、X射线衍射(XRD)、透射电镜(TEM)等设备对试样强化层形貌和纳米组织进行检测,采用显微硬度计进行显微硬度测量。测试结果表明:TC6钛合金激光喷丸表面完整性好,未在表面引入微裂纹,表面粗糙度较传统表面强化低;激光喷丸后距离表面200μm范围内α相在冲击波作用下压缩伸长,α相和β相细化,保温后SEM测试显示强化层组织和强化层深度未发现明显变化;强化后衍射峰变宽,说明强化层发生剧烈塑性变形导致晶粒细化,并留有残余应变,未发现新的衍射峰说明强化过程中没有发生相变;强化后TC6钛合金表层产生纳米晶,保温后强化层位错密度降低,纳米晶晶界更加清晰,未发现纳米晶长大;激光喷丸硬度影响层达500μm,表面硬度提高12.2%,保温后表面显微硬度降低10HV0.5,硬化深度未发现变化。以上研究表明,TC6激光喷丸纳米组织和显微硬度在623K温度下具有较好的热稳定性,有利于提高钛合金的抗疲劳、抗磨损和抗应力腐蚀的性能,从而突破了美国规范AMS2546中关于钛合金只能在589K温度下应用的限制。
Laser shot peening was performed on the TC6 titanium alloy by using Nd: YAG high power laser, and the partially strengthened sample was vacuum-insulated at 623K for 10h. The morphology of the strengthened layer and the structure of the nanostructures were examined by means of AFM, SEM, EBSD, XRD and TEM. Microhardness tester Microhardness measurement. The results show that the surface integrity of laser shot peening of TC6 titanium alloy is good, the micro-cracks are not introduced on the surface, the surface roughness is lower than that of the traditional surface hardening. After the laser shot peening, the α phase is compressed and extended under the impact wave, α phase and β phase refinement. SEM test shows that there is no obvious change in the microstructure and strengthening depth of the strengthened layer, and the broadening of the diffraction peak after strengthening shows that the intense plastic deformation of the strengthening layer leads to grain refinement and residual strain , No new diffraction peaks were found indicating that no phase transition occurred during the strengthening process; nanocrystals were formed on the surface of the TC6 titanium alloy after strengthening, and the dislocation density of the strengthening layer decreased after the heat preservation. The nanocrystalline grain boundaries were clearer and no nanocrystal growth was found. Shot peening hardness of the affected layer of 500μm, the surface hardness increased by 12.2%, the surface microhardness after heat reduction 10HV0.5, no change in the depth of hardening. The above studies show that, TC6 laser peening nano-microstructure and microhardness at 623K temperature has good thermal stability, help to improve the anti-fatigue resistance, wear resistance and stress corrosion resistance of titanium alloys, which broke through the United States Code AMS2546 In the titanium alloy can only be used at 589K temperature limits.