共查询到19条相似文献,搜索用时 93 毫秒
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金属零件在切削加工后,其被加工表面会形成一残余应力层,其所引起零件的变形是影响精密弱刚性零件精度的重要的因素。为了预测Ti6Al4V零件因铣削加工表面残余应力而引起的变形,本文介绍一种测量表面等效残余应力及其作用深度的方法而达到此目的。通过对被加工面的对面进行两次腐蚀去除材料的操作使得零件的厚度和中性层的位置发生变化,测量此过程中零件挠度和表面应变的变化,进而计算得铣削加工引起的零件表面等效残余应力及其作用深度值。通过有限元分析验证该方法得到的结果,发现有限元计算得到的零件挠度和应变的变化与实际测量值非常吻合,因此可以断定该方法得到的结果是正确的,其可以正确评估铣削加工引起的表面残余应力性质和大小并能准确预测零件铣削加工后因表面残余应力而引起的工件的变形量,从而可以预测零件是否满足精度要求。 相似文献
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《稀有金属材料与工程》2015,(10)
同时考虑测量精度、测量可行性以及节约材料诸多方面的问题,运用有限元验证的方法确定零件合适的长度。同时运用精度较高的基于有限元分析的修正方法结合X射线法测量Ti6Al4V管件车削加工引起的表面残余应力,分析不同切削参数以及退火处理对表面残余应力的影响。结果显示:切削速度、进给量以及切削深度在指定范围内增大时会导致表面切削和进给方向的压应力增大,退火处理会使得表面2个方向的残余应力减小将近85%。 相似文献
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结构陶瓷磨削表面的残余应力 总被引:6,自引:0,他引:6
本文应用X射线衍射法就几种常用结构陶瓷磨削表面残余应力的形成机理,状态特征与磨削用量的关系进行实验研究。结果表明:磨削表面的残余应力由毛坯表面层原始应力σ0和磨削残余应力Δσ两部分组成。σ0受陶瓷材料、毛坯形状及烧结工艺的影响有较大的变化,Δσ的大小及拉压特性取决于陶瓷的磨削过程特征和磨削温度。 相似文献
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陶瓷加工后表面残余应力的测量通常采用一维X射线衍射线探测法,该方法存在测量过程烦琐、效率低、成本高等问题,因此采用新型快速二维面探测X射线衍射残余应力测量方法,对碳化硅陶瓷表面的残余应力进行测量,实验中测量了3种不同品牌碳化硅工件的初始表面和抛光后表面的残余应力。结果表明:此新方法单次测量即可获得样品500点的衍射信息,特别适用于陶瓷材料的应力测量。同时还发现:对于被加工表面的残余压应力,抛光加工最高能够消除近80%的残余应力,但不能改变工件的残余应力分布。 相似文献
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工程陶瓷磨削表面残余应力的测量新方法 总被引:3,自引:0,他引:3
磨削加工后工程陶瓷零件表面会产生残余应力。X射线衍射法是用来测量磨削加工后工程陶瓷中残余应力的可靠测量手段。传统的X射线衍射法称之为sin^2ψ法,通常只能测量工件表层的残余应力;本文介绍了一种残余应力测量新方法,该方法联合使用sin^2ψ法和掠入射X射线衍射法从而得到残余应力在试件中的深度分布。如果考虑X射线的折射,在一系列掠射角下采集到的X射线衍射花样的有效穿透深度和衍射角必须进行折射校正。最后,用这种方法得到的残余应力值是X射线照射的所有层的平均值。 相似文献
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The linear friction welding process of Ti6Al4V was modeled and computed for obtaining the residual stresses.Temperature,stress and strain fields were simulated,based on which,the residual stresses were... 相似文献
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针对Hastelloy C276大径厚比薄壁筒形件,建立三维弹塑性有限元模型,通过不同工艺参数(毛坯壁厚、减薄率、进给比)对其表面残余应力的影响进行分析,研究了筒形件变薄旋压残余应力的分布规律,提出了合理的旋压工艺参数范围,并通过旋压实验对仿真模型进行了实验验证.研究表明:壁厚越薄,残余应力的绝对值越大,变化幅度也越大;表面残余应力的绝对值随减薄率的增加而增加;随着进给比的增大,各向残余应力的变化情况都不相同,周向和轴向残余应力的绝对值随进给比的增加而增加,而径向残余应力相反. 相似文献
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《Science & Technology of Welding & Joining》2013,18(7):525-533
AbstractThis paper reports the results of a systematic investigation of residual stresses as a function of welding speed in a set of Ti–6Al–4V friction stir welds. The investigation focuses on residual stress but links these data with microstructural information derived from micrographs and hardness measurements as well as mechanical testing results. Residual stresses were determined using energy dispersive synchrotron X-ray diffraction, which allows phase specific stresses to be distinguished. The data presented in this paper demonstrate that welds with high tensile properties can be obtained, which also have relatively low peak tensile residual stress values of ~30% of the tensile strength. The data also show a clear correlation between heat input and the width of the residual stress profile. 相似文献
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QT600球墨铸铁激光淬火相变层残余应力测试研究 总被引:1,自引:0,他引:1
利用CO2激光器对QT600球墨铸铁进行了激光淬火处理试验,用X-350A型X射线应力仪测定QT600激光淬火后的表面及其断面残余应力规律,分析了QT600激光淬火后的残余应力形成机理。试验结果表明,在CO2激光工艺参数为输出功率P=800-1200W、光斑直径=3.5-4.0mm、扫描速度V=6-8mm/s的条件下,QT600激光淬火后的残余应力均为压应力,其值在-250MPa以上。在QT600材料表面及断面上测定了Ψ=0°4、5°和90°方向上的残余应力,其值的变化范围小,表明淬火后材料组织结构比较均匀,无明显织构,有利于提高材料的使用寿命。 相似文献
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Au/NiCr/Ta films were prepared by plating and then annealed at 400 °C in Ar gas for an hour. The Au diffraction peak positions including incidence angles 0°, 15°, 30°, and 45° were measured by a glancing incidence X-ray diffraction (GIXRD) method. Residual stresses were then calculated using the sin2ψ method. The results indicate that the residual stress in the as-deposited Au/NiCr/Ta films was about 50 MPa, but was decreased down to − 5 MPa in average after samples annealing. The XRD analysis on crystal orientation shows that only the diffraction peaks of Au were found. There are no alloying phases in the plating Au film, and the interlayer of NiCr and Ta is too thin to be detected by the conventional XRD. The XRD also revealed that the films are highly textured with Au-(111) or a mixture of Au-(111) and Au-(200) orientation, and the (111)/(200) intensity ratio decreases after samples annealed. 相似文献
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采用热-弹塑性三维有限元法研究激光熔透焊接Ti6Al4V合金的残余应力,并采用小孔法测量焊接残余应力以和计算结果进行比较.有限元计算时,建立了以焊缝形貌尺寸为参数的统一锥形热源模型来模拟不同热输入时的焊接温度场,并讨论了边界条件和有限元网格大小的确定.研究结果表明:采用焊缝轮廓尺寸作为热源参数能准确模拟焊缝横截面轮廓;钛合金激光熔透焊接的纵向残余应力分布梯度陡;在焊件表面和内部残余应力分布趋势不同,采用小孔法测量的残余应力分布和计算的焊接件内部残余应力分布相似. 相似文献
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Zhong Zhou Sagar Bhamare Gokul Ramakrishnan Seetha R. Mannava Kristina Langer Youhai Wen Dong Qian Vijay K. Vasudevan 《Surface & coatings technology》2012,206(22):4619-4627
Laser shock peening (LSP) induced residual stresses in Ti–6Al–4V, and their thermal relaxation due to short-term exposure at elevated temperatures are investigated by an integrated modeling/simulation and experimental approach. A rate and temperature-dependent plasticity model in the form of Johnson–Cook (JC) has been employed to represent the nonlinear constitutive behavior under both LSP and thermal loads. By comparing the simulation results with experimental data, model parameters for Ti–6Al–4V are first calibrated and subsequently applied in analyzing the thermal stability of the residual stress in LSP-treated Ti–6Al–4V. The analysis shows that the magnitude of stress relaxation increases with the increase of applied temperature due to material softening. Most of stress relaxation occurs before 10 min to 20 min exposure in this study, and stress distribution becomes more uniform after thermal exposure. An analytical model based on the Zener–Wert–Avrami formula is then developed based on the simulation results. The activation enthalpy of the relaxation process for laser shock peened Ti–6Al–4V is determined to be in the range of 0.71 eV to 1.37 eV. 相似文献