中国激光, 2013, 40 (8): 0803006, 网络出版: 2013-07-26
激光喷丸提高TC11钛合金高周疲劳性能的试验研究
Experimental Study on Improving High-Cycle Fatigue Performance of TC11 Titanium alloy by Laser Shock Peening
激光器 激光冲击强化 TC11钛合金 疲劳极限 断口分析 强化机制 lasers laser shock peening TC11 titanium alloy fatigue limit fracture analysis strengthening mechanism
摘要
对TC11钛合金标准疲劳试件进行激光喷丸处理,利用高周振动疲劳试验验证强化效果,通过断口观察分析疲劳机理,再从微观组织、残余应力和显微硬度等方面分析激光喷丸提高TC11钛合金疲劳性能的强化机制。试验结果表明,强化后疲劳试件的疲劳极限由483 MPa提高到593 MPa;强化试件的裂纹源位于次表层深0.2 mm处,平坦区扩大,快速扩展区产生大量二次裂纹和排列紧密的疲劳条带。表层发生较高程度细化,形成尺寸为40~80 nm的纳米晶;并引入高数值残余压应力,表面残余应力达-591.5 MPa,其塑性变形层深度达1 mm,且表面硬度提高19%。TC11钛合金标准疲劳试件强化后疲劳强度提高主要是因为高程度组织细化和高数值残余压应力的综合作用,进而阻碍裂纹萌生和降低扩展速率。
Abstract
The standard vibration fatigue specimens, made of TC11 titanium alloy, are treated by laser shock peening (LSP). The high-cycle vibration tests are conducted to verify the reinforcement effect, and the fracture analysis is utilized to analyze the fatigue mechanism of the treated specimens. The strengthening mechanism of fatigue performance is explained by the experiments of microstructure, residual stress and microhardness. The tests results show that the fatigue limit is improved from 483 MPa to 593 MPa by LSP. Fatigue crack of specimens treated by LSP initiates in the subsurface of 0.2-mm depth with a greater flatness area and lots of second-cracks and tight fatigue bands. A layer with nanocrystals is generated on the surface by LSP, and the size of nanocrystal is about 40~80 nm. LSP introduce a great compressive residual stress in the material with a 1-mm thick plastic deformation layer. The residual stress in the surface can reach -591.5 MPa, while the surface hardness is increased by 19%. The combined actions of high structure refinement and high compressive residual stress are the main causes of the fatigue performance improvement, which block fatigue crack initiating and reduce crack growth rate.
聂祥樊, 何卫锋, 臧顺来, 王学德, 李玉琴. 激光喷丸提高TC11钛合金高周疲劳性能的试验研究[J]. 中国激光, 2013, 40(8): 0803006. Nie Xiangfan, He Weifeng, Zang Shunlai, Wang Xuede, Li Yuqin. Experimental Study on Improving High-Cycle Fatigue Performance of TC11 Titanium alloy by Laser Shock Peening[J]. Chinese Journal of Lasers, 2013, 40(8): 0803006.