非连续式零搭接率复合路径激光冲击强化对航空钛合金TC4细节疲劳额定强度截止值的影响  

Effect of a Non-Continuous Composite Path with Zero Overlapping Rate on Cutoff Value of Detail Fatigue Rated Strength of Aerospace Titanium Alloy TC4 Under Laser Shock Peening

作　　者：叶铖润 孙剑宇 龙应斌 赵绪杰 张增焕 郁峥嵘 彭宇杰 冷雨欣[1] Ye Chengrun;Sun Jianyu;Long Yingbin;Zhao Xujie;Zhang Zenghuan;Yu Zhengrong;Peng Yujie;Leng Yuxin(State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-Intense Laser Science,Shanghai Institute of Optics and Fine Mechanics(SIOM),Chinese Academy of Sciences(CAS),Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Commercial Aircraft Corporation of China Ltd.(COMAC),Shanghai200126,China)

机构地区：[1]中国科学院上海光学精密机械研究所强场激光物理国家重点实验室,上海201800 [2]中国科学院大学材料科学与光电子工程中心,北京100049 [3]中国商用飞机有限责任公司,上海200126

出　　处：《中国激光》2024年第20期53-65,共13页Chinese Journal of Lasers

基　　金：国家自然科学基金(U21A20138);上海启明星计划(21QA1410200);中国科学院青年创新促进会项目(2020248);国家商用飞机制造工程技术研究中心创新资助项目(COMAC-SFGS-2021-603)。

摘　　要：本研究旨在探究激光冲击强化(LSP)对TC4钛合金疲劳寿命的影响。在不同的激光功率密度和搭接率下,采用单次路径光斑搭接率为0、整体搭接率为50%的非连续式强化策略,以叠加矩形与C形的复合路径对TC4合金试样表面进行激光冲击强化。使用PROTO Proflometer LP200激光轮廓仪测试强化后试样的表面粗糙度,结果显示激光功率密度和搭接率对粗糙度的影响并没有呈现出明显的规律。使用LXRD X射线衍射仪测试了激光冲击强化试样的残余压应力,结果显示:当激光功率密度为12 GW/cm^(2)时,获得了最大残余压应力和最大残余压应力深度,分别为-669.67 MPa和0.8 mm,此时TC4合金的细节疲劳额定强度截止值(DFR_(cutoff))是未激光冲击强化合金的120.76%。这表明采用非连续式、单次零搭接率、叠加矩形路径与C形路径的复合路径进行激光冲击强化,可以使TC4试样的DFR_(cutoff)显著提升,从而延长其疲劳寿命。Objective The TC4 titanium alloy is the earliest and most widely used titanium alloy in aviation and aerospace structures.However,the TC4 titanium alloy exhibits high sensitivity to notches,which decreases its fatigue resistance and leads to fatigue fracture during use.The detail fatigue rating(DFR)is a parameter that is commonly used in civil aviation to assess the fatigue resistance of the TC4 titanium alloy.Laser shock peening(LSP)is a novel strengthening method that has been proven to effectively improve the fatigue life of the TC4 titanium alloy.Previous research on LSP primarily assesses the fatigue resistance of the TC4 titanium alloy by using methods such as analyzing the S-N(residual stress versus fatigue life)curve of the residual stress,examining fracture surfaces,or conducting finite element simulations.However,there is a limited number of studies that directly investigate the enhancement of TC4 fatigue resistance via LSP based on the DFR_(cutoff) value.In addition,during the LSP of TC4 samples,plasma easily penetrates the water flow layer in the notch area,and the laser directly impacts the surface of the TC4 notch area,which leads to the ablation and damage of the titanium alloy surface.This,in turn,reduces the DFR_(cutoff) value and service life of the titanium alloy.Therefore,this article presents a novel LSP strategy that utilizes a discontinuous composite path,consisting of a C-shaped path and a matrix,with a zero overlapping rate.The objective is to investigate the potential of LSP to enhance the fatigue resistance of TC4 materials by considering the DFR_(cutoff) value.This study serves as a valuable reference for future research on the improvement of fatigue resistance in aviation TC4 alloys via LSP.Methods First,the TC4 alloy was fabricated into specimens with a gage section geometry of 290 mm×40 mm×7 mm.Subsequently,the specimens underwent a laser shock peening treatment.The surface roughness of the TC4 alloy treated by LSP was measured using a PROTO Proflometer LP200 laser profilometer.Th

关 键 词：激光冲击强化 复合路径 钛合金TC4 细节疲劳额定强度截止值 疲劳寿命 

分 类 号：TG146.2[一般工业技术—材料科学与工程]