新型光斑搭接对平顶激光冲击钛合金力学性能的影响
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摘要
针对平顶光束的特点,为简化工艺,提高加工效率,提出了一种简化加工过程的搭接率工艺方法。采用一种纵向25%、横向56.5%的搭接率工艺,并对该搭接率下的残余应力、显微硬度、高周疲劳极限等力学性进行验证,对比其与传统50%搭接率下的性能差异。结果表明:在新型搭接率下,平顶激光冲击钛合金表面产生的残余压应力均值为-564.5 MPa,影响深度达0.82 mm;在传统搭接率下,表面产生的残余压应力均值为-559.2 MPa,影响深度达0.81 mm。在新型和传统两种搭接率下,平顶激光冲击钛合金表面重叠次数多的位置,显微硬度平均值分别为570.9和562.6 HV0.3,重叠次数少的显微硬度平均值分别为432.1和453.4 HV0.3;钛合金截面上的硬化层深度均为0.4 mm。在新型和传统两种搭接率下,平顶光束冲击钛合金的疲劳极限分别为256.3和264.6 MPa。基于平顶光束,与传统工艺相比,简化的新型搭接率工艺可以获得较好的力学性能,并提高加工效率,降低加工成本。
To simplify the process and improve the efficiency, a novel overlapping method was proposed. The novel overlapping rate was set as longitudinal 25% and lateral 56.5%. The residual stress, micro-hardness, and high cycle fatigue limit of the titanium alloy after laser treatment with this overlap were investigated. The comparison of the above mentioned mechanical properties between the new overlap and the traditional 50% overlap was also studied. Results show that the mean value of surface compressive residual stress induced by laser shock peening(LSP) is –564.5 MPa with the new overlap, and the influenced depth reaches 0.81 mm. With the traditional overlap, the surface compressive residual stress induced by LSP is–564.5 MPa and the depth of compressive residual stress is 0.82 mm. The surface micro-hardness of titanium alloy after LSP at more overlapping regions are 570.9 and 562.6 HV0.3 and that at less overlapping regions are 432.1 and 453.4 HV0.3,respectively. The layer of compressive residual stress after LSP are both 0.4 mm. The high cycle fatigue limit of titanium alloy after LSP are 256.3 and 264.6 MPa with the new and traditional overlapping rates, respectively. Based on the flat-toped laser beam, the mechanical properties of the titanium alloy after LSP with this novel simplified overlapping rate process can be obtained as same as that with 50% overlapping rate. The processing efficiency increases and the cost is reduced.
To simplify the process and improve the efficiency, a novel overlapping method was proposed. The novel overlapping rate was set as longitudinal 25% and lateral 56.5%. The residual stress, micro-hardness, and high cycle fatigue limit of the titanium alloy after laser treatment with this overlap were investigated. The comparison of the above mentioned mechanical properties between the new overlap and the traditional 50% overlap was also studied. Results show that the mean value of surface compressive residual stress induced by laser shock peening(LSP) is –564.5 MPa with the new overlap, and the influenced depth reaches 0.81 mm. With the traditional overlap, the surface compressive residual stress induced by LSP is–564.5 MPa and the depth of compressive residual stress is 0.82 mm. The surface micro-hardness of titanium alloy after LSP at more overlapping regions are 570.9 and 562.6 HV0.3 and that at less overlapping regions are 432.1 and 453.4 HV0.3,respectively. The layer of compressive residual stress after LSP are both 0.4 mm. The high cycle fatigue limit of titanium alloy after LSP are 256.3 and 264.6 MPa with the new and traditional overlapping rates, respectively. Based on the flat-toped laser beam, the mechanical properties of the titanium alloy after LSP with this novel simplified overlapping rate process can be obtained as same as that with 50% overlapping rate. The processing efficiency increases and the cost is reduced.
引文
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[17]LUO K Y,LIN T,DAI F Z,et al.Effects of overlapping rate on the uniformities of surface profile of LY2 Al alloy duringmassive laser shock peening impacts[J].Surface&Coatings Technology,2015,266:49-56.
[18]胡永祥.激光冲击处理工艺过程数值建模与冲击效应研究[D].上海:上海交通大学,2008.Hu Y X.Research on the numerical simulation and impact effects of laser shock processing[D].Shanghai:Shanghai Jiaotong University,2008(in Chinese).
[19]NIE X F,HE W F,ZHOU L C,et al.Experiment investigation of laser shock peening on TC6 titanium alloy to improve high cycle fatigue performance[J].Materials Science&Engineering A,2014(594):161-167.
[20]卢光辉.基于磨削加工表面完整性的滚动接触疲劳寿命预测[D].上海:上海交通大学,2009.LU G H.Prediction of rolling contact fatigue life based on surface intergrity of grinding process[D].Shanghai:Shanghai Jiaotong University,2009(in Chinese).
[2]聂祥樊,何卫锋,臧顺来,等.激光冲击对TC11钛合金组织和力学性能的影响[J].航空动力学报,2014,29(2):321-327.NIE X F,HE W F,ZANG S L,et al.Effect on structure and mechanical properties of TC11 titanium alloy by laser shock peening[J].Journal of Aerospace power,2014,29(2):321-327(in Chinese).
[3]李媛,何卫锋,周舟.变参数激光冲击TC17钛合金疲劳裂纹扩展特性[J].激光与红外,2017,47(10):1228-1233.LI Y,HE W F,ZHOU Z.Fatigue crack propagation property of TC17 titanium alloy by laser shock peening[J].LASER&INFRARED,2017,47(10):1228-1233(in Chinese).
[4]张明扬,朱颖,郭伟,等.激光冲击强化对TC17钛合金高周疲劳性能的影响[J].激光技术,2017,41(2):231-234.ZHANG M Y,ZHU Y,GUO W,et al.Effects of laser shock processing on fatigue properties of TC17 titanium alloy[J].LASER TECHNOLOGY,2017,41(2):231-234(in Chinese).
[5]CAO Y,SHIN Y,WU B.Parametric study on single shot and overlapping laser shock peening on various metals via modeling and experiments[J].Manufacturing Science and Engineering,2010,132:061010.
[6]ROBERT A,WILLIAM R,STEVEN E,et al.Prediction and characterization of residual stresses from laser shock peening[J].International Journal of Fatigue,2012,36:98-106.
[7]花银群,蔡峥嵘,陈瑞芳,等.TC4钛合金激光搭接冲击强化的实验和数值模拟[J].激光技术,2010,34(5):632-635.HUA Y Q,CAI Z R,CHEN R F,et al.Experiment and numerical simulation of overlapping laser shock processing in TC4 titanium alloy[J].LASER TECHNOLOGY,2010,34(5):632-635(in Chinese).
[8]HU Y X,YAO Z,HU J.3D-FEM simulation of laser shock processing[J].Surface&Coatings Technology,2006,201(3-4):4126-4135.
[9]HU Y X,YAO Z.Overlapping rate effect on laser shock processing of 1045 steel by small spots with Nd:YAG pulsed laser[J].Surface&Coatings Technology,2008,202(8):1517-1525.
[10]HU Y X,YAO Z.Numerical simulation and experimentation of overlapping laser shock processing with symmetry cell[J].International Journal of Machine Tools and Manufacture,2008,48(2):152-162.
[11]苏波泳,孙桂芳,裴旭,等.冲击波动态传播特性对激光喷丸残余应力场的影响[J].中国表面工程,2018,31(2):15-22.SU B Y,SUN G F,PEI X,et al.Influence of shock wave transient transmission on laser peened residual stress field[J].China Surface Engineering,2018,31(2):15-22(in Chinese).
[12]程龙.不同激光冲击工艺参数对40Cr钢表面应力应变影响的模拟试验研究[D].镇江:江苏大学,2017.CHENG L.Experimental study on the effect of different laser impact process parameters on the stress and strain of40Cr steel surface[D].Zhenjiang:Jiangsu University,2017(in Chinese).
[13]CAO Z W,XU H,ZOU S,et al.Investigation of surface integrity on TC17 titanium alloy treated by square-spot laser shock peening[J].Chinese Journal of Aeronautics,2012(04):650-656.
[14]余天宇,戴峰泽,张永康,等.平顶光束激光冲击2024铝合金诱导残余应力场的模拟与实验[J].中国激光,2012,39(10):1003001.YU T Y,DAI F Z,ZHANG Y K,et al.Simulation and experimental study on residual field of 2024 aluminum alloy induced by flat-top laser beam[J].Chinese Journal of Lasers,2012,39(10):1003001(in Chinese).
[15]朱然,张永康,孙桂芳,等.三维平顶光束激光冲击2024铝合金的残余应力场数值模拟[J].中国激光,2017,44(8):0802007.ZHU R,ZHANG Y K,SUN G F,et al.Numerical simulation of residual stress fields in three-dimensional flattened laser shocking of 2024 aluminum alloy[J].Chinese Journal of Lasers,2017,44(8):0802007(in Chinese).
[16]颜鸣皋.中国航空材料手册[M].北京:中国标准出版社,2004.YAN M G.Chinese handbook of aeronautical material[M].Beijing:Chinese Specification Press,2004(in Chinese).
[17]LUO K Y,LIN T,DAI F Z,et al.Effects of overlapping rate on the uniformities of surface profile of LY2 Al alloy duringmassive laser shock peening impacts[J].Surface&Coatings Technology,2015,266:49-56.
[18]胡永祥.激光冲击处理工艺过程数值建模与冲击效应研究[D].上海:上海交通大学,2008.Hu Y X.Research on the numerical simulation and impact effects of laser shock processing[D].Shanghai:Shanghai Jiaotong University,2008(in Chinese).
[19]NIE X F,HE W F,ZHOU L C,et al.Experiment investigation of laser shock peening on TC6 titanium alloy to improve high cycle fatigue performance[J].Materials Science&Engineering A,2014(594):161-167.
[20]卢光辉.基于磨削加工表面完整性的滚动接触疲劳寿命预测[D].上海:上海交通大学,2009.LU G H.Prediction of rolling contact fatigue life based on surface intergrity of grinding process[D].Shanghai:Shanghai Jiaotong University,2009(in Chinese).