焊接残余应力与变形

1、Residual Stresses and Distortions in Welded Structures: Modeling, Analysis, and Mitigation 焊接结构中残余应力和变形 建模、分析与控制 （Dr. Pingsha Dong) Professor and Northrop Grumman Endowed Chair Director, Center for Advanced Marine Structures and Fabrication (CAM- SF) School of Naval Architecture and Marine Engineeri

2、ng The University of New Orleans 1 焊接残余应力与变形 声明 2 焊接残余应力与变形 Table of Content 目录 nIntroduction/background 绪言/背景 6 nResidual stress/distortion development mechanisms 残余应力/变形产生的机理 16 nModeling and analysis requirements 建模和分析需要考虑内容 25 lLength scale considerations 尺度考虑 38 lHeat flow modeling 热流建模 48 lWel

3、d material modeling 焊接材料建模 59 lDistortion modeling 焊接变形建模 73 nResidual stress measurements and model validations 残余应力测量与模型验证 92 nResidual stresses in repair welds 补焊中的残余应力 112 nResidual stresses from other welding processes 其它焊接工艺产生的残余应力 126 nResidual stress and distortion mitigation technique 残余应力与

4、变形的控制技术 lWelding procedure/sequence 焊接过程/顺序 146 lUniform PWHT 整体焊后热处理 151 l Local PWHT/related stress improvement techniques 159 局部焊后热处理/相关的应力改善技术 lProof-tests 试验与验证 172 nHow to generalize residual stress distribution 如何得到残余应力的分布 191 nFracture mechanics treatment 破裂力学的处理 213 nSome well-documented ca

5、se studies 一些经典案例 lStress corrosion cracking 应力侵蚀裂纹 226 lBrittle fracture 脆性裂纹 241 lCreep damage 扭曲破坏 246 lDistortion control 变形控制 251 nFatigue assessment incorporating residual stresses 考虑残余应力的疲劳寿命评估 265 3 焊接残余应力与变形 Related Major Awards and Recognitions Received 获得的主要奖励及荣誉 n IIW 2008 E. Paton Prize

6、 n SNAME 2007 Elmer L Hann Award n R&D Magazines R&D 100 Award (2006) n TIME Magazine 2005 Math Innovator n Aviation Week & Space Technology: Aerospace 2004 Laurels n Award n AWS 2004 R.D. Thomas Award n SAE 2003 Henry Ford II Distinguished Award for Excellence n in Automotive Engineering n ASME 200

7、2 G.E.O. Widera Literature Award 4 焊接残余应力与变形 Course Objectives 课程目的 n Demystify the complexity of residual stresses and effects on engineering structures 阐明阐述残余应力的复杂性及其对工程结构的影响 n Provide a state of the art assessment 提供一个达到最新技术发展水平的评价 l what we know about residual stresses and distortions 我们所了解的残余应力

8、和变形 l current status of modeling and measurement techniques 建模与测量技术现状 n Provide practical guidance on solving typical engineering problems, e.g., 为典型工程问题的解决提供实用性指导 l how to effectively idealize a actual residual stress problem? 如何有效地理想化一个实际的残余应力问题?（？） l how to devise an effective solution strategy?

9、如何找到一个有解决方案的策略? l how to interpret and validate a given solution? 如何解释并验证给定的解决方案? l how to effectively incorporate residual stresses in structural? 如何在结构性能评估中有效地引入残余应力? l performance evaluation? 性能评价? 5 焊接残余应力与变形 An Overview of Advanced Weld Modeling Capabilities: Fusion Welding 先进的焊接模型能力概述: 熔化焊 6 焊

10、接残余应力与变形 An Overview of Advanced Weld Modeling Capabilities: Solid Joining 先进的焊接模型能力概述: 固态连接 7 焊接残余应力与变形 Residual Stresses in a Hot-Rolled Plate and Effects on Cutting 热轧板中的残余应力及其对下料精度的影响 8 焊接残余应力与变形 Importance of Understanding Residual Stresses and Distortions - An Aerospace Example 理解残余应力和变形的重要性-以

11、航天飞机为例 9 焊接残余应力与变形 Residual Stress Induced Stress Corrosion Cracking -Tube to Tube Sheet Welds 残余应力引起的应力侵蚀裂纹 管子与管板的焊接 10 焊接残余应力与变形 Weld Residual Stress Effects on Fatigue Performance: Weld Sequencing 焊接残余应力对疲劳性能的影响 焊接顺序 11 焊接残余应力与变形 Brittle Fracture in Beam to Column Connection in North Ridge Earthq

12、uake 北卡州North Ridge地震中梁-柱连接中的脆性断裂 n Brittle Fracture of welded beam-to-column moment resisting frames 梁-柱连接抗力矩构架的脆性裂纹 n All weld properties satisfy Building Code requirements 所有的焊接特性均满足建筑法规要求 n Causes for brittle fracture? 什么导致了脆性裂纹？ 12 焊接残余应力与变形 Current Status on Residual Stress Prescriptions in Cu

13、rrent Codes and Standards 当前规范和标准中的残余应力规定 13 焊接残余应力与变形 Implications on Fracture Assessment (Bouchard, 01) 对断裂评估的启示（ Bouchard, 01 ）(?) 14 焊接残余应力与变形 Distortions in Shipbuilding 造船中的焊接变形 多隔板（？）船舷板对接焊后变形 15 焊接残余应力与变形 Analysis of Residual Stresses and Distortions 残余应力与变形分析 n Complex problem nature: 复杂的问题

14、本质: l Multi-facet physics 多方面的物理现象 l Multi-scale mechanics 多尺度力学 n Academic research: Every aspect can be intellectually challenging 学术研究：每一方面是对智力的挑战 n Practical application: 实际应用: l good assumptions are essential 好的假设是基础 l Understanding fundamentals is the key 对基本原理的理解是关键 16 焊接残余应力与变形 Residual Stre

15、ss Development Mechanisms 残余应力的产生机制 n Necessary and sufficient conditions 充分必要条件 l Localized plastic strain 局部的塑性应变 n Sources 起源 l (Thermal) stresses （热）应力 Nonlinear temperature gradients 非线性的温度变化 CTE mismatch in dissimilar material joints 不同材料接头热膨胀系数不一致 l Stresses sufficient to produce local yieldi

16、ng 应力足以产生局部屈服 n Residual stresses: 残余应力: l Stress distributions retained in a component upon cooling or unloading 冷却和卸载后应力仍分布在构件中 l Accompanied by a permanent deformation field 伴随有永久变形 17 焊接残余应力与变形 Localized Thermal-Mechanical Phenomenon in welding 焊接过程中局部的热-力现象 n Fusion-based welding 基于熔化的焊接 l High

17、ly localized rapid heating/cooling 高度的局部快速加热/冷却 l Nonlinear temperature gradient 非线性的温度梯度 l Localized plastic deformation 局部的塑性变形 n Some solid state based joining, e.g., brazing, DB, etc (with uniform heating/cooling) 一些基于固态的连接，如铜焊、DB焊接等（均匀加热/冷却） l CTE mismatch produces high residual stresses 热膨胀系数不

18、一致导致高残余应力 l w/ or w/o localized plastic deformation 有或没有局部塑性变形 18 焊接残余应力与变形 An Example: Residual Stress Distributions in a Single-Pass T-Fillet Weld 例：单道焊T型角焊缝残余应力分布 19 焊接残余应力与变形 Distortions after Welding 焊后变形 20 焊接残余应力与变形 Remarks 注意 n Residual stresses 残余应力 l Necessary and sufficient conditions: lo

19、calized plastic deformation 充要条件：局部塑性变形 l Final residual stress distribution in a component must satisfy equilibrium conditions in a component after welding 构件焊后残余应力的最终分布必须满足平衡条件 Component geometry 构件几何结构 External restraint conditions during welding 焊接过程中的外部拘束条件 Welding procedure, etc 焊接工序等 n Distor

20、tions may not be directly related to residual stresses and their distribution 变形可能和残余应力及其分布不直接相关 l History dependency 历史相关性 l Material/geometry nonlinearity 材料和几何的非线性 l Stable versus unstable deformation behavior 稳定与非稳定的变形行为 21 焊接残余应力与变形 A Side Heating Example: Elastic-Thermo mechanical Behavior 单侧加

21、热的例子：弹性热力行为 22 焊接残余应力与变形 Side Heating Example: Elastic-Plastic Thermo mechanical Behavior 单侧加热的例子：弹塑性热力行为 23 焊接残余应力与变形 How About Other Welding Related Phenomena? 其它焊接相关现象怎么样? 24 焊接残余应力与变形 Modeling/Analysis Requirements 建模/分析要求 n We must simplify the complex multi-physics and multi-scale mechanics ph

22、enomena without losing useful information for engineering applications 在不丢失工程应用的有用信息的前提下，必须对复杂的多物理、多尺度力学现象进行简化 n How to do that? 如何去做？ l Identify the dominant residual stress development mechanisms (e.g., the 1D and 2D examples) 确定主要残余应力的产生机制（如1D或2D情况） l Bound some of the effects by conducting param

23、etric analyses using validated FE procedures, with various levels of procedure refinements 一些影响通过有效的有限元程序进行导热参数分析，（？） Thermal/mechanical modeling procedures 热/力建模过程 High-temperature material behavior, e.g., phase transformation effects, 高温材料性能,如相变影响 Variation in welding procedures, joint geometries,

24、 etc 焊接过程、接头几何结构等变化 l Investigate what a large amount of experimental data tells us 对大量的实验数据进行调研 l Lots of hard work without taking this course 很多难题没有包含在内 25 焊接残余应力与变形 A Butt Joint in a Thin Sheet FE Simulation Using a Special Shell Model (2-Pass Weld) 薄板焊接的对接接头用特定的壳模型进行有限元仿真 （两道焊） 26 焊接残余应力与变形 Tran

25、sverse Residual Stress Variation Along Weld Direction and Measurements 沿焊接方向的横向残余应力变化和测量 27 焊接残余应力与变形 Residual Stress Distributions After Weld Repair 补焊后残余应力的分布 28 焊接残余应力与变形 Residual Stress Predictions versus X-Ray Measurements 残余应力预测结果与X射线测量结果的对比 29 焊接残余应力与变形 Residual Stresses in a Typical Butt Joi

26、nt 典型对接接头中的残余应力 n Residual stresses along weld 沿焊接方向的残余应力 l High restraint conditions 强约束条件 l Insensitive to various parameters 参数不敏感 n Residual stress perpendicular to weld 垂直于焊接方向的残余应力 l Strongly depending on joint geometry 严重依赖于接头几何 l Sensitive to welding procedures 对焊接过程敏感 30 焊接残余应力与变形 Residual

27、Stresses and Distortions in a T Joint - Restraint Effects T型接头的残余应力和变形拘束条件的影响 31 焊接残余应力与变形 Material Strength Effects Transverse Residual Stresses 材料强度的影响横向残余应力 32 焊接残余应力与变形 Material Strength Effects Longitudinal Residual Stresses 材料强度的影响纵向残余应力 33 焊接残余应力与变形 Travel Speed Effects - Transverse 焊接速度的影响横向

28、 34 焊接残余应力与变形 Travel Speed Effects Longitudinal 焊接速度的影响纵向 35 焊接残余应力与变形 Pass Sequence Effects on Transverse Residual Stresses 焊道顺序对横向残余应力的影响 36 焊接残余应力与变形 Pass Sequence Effects on Longitudinal Residual Stresses 焊道顺序对纵向残余应力的影响 37 焊接残余应力与变形 How to Quantify Residual Stress Results in terms of Their Signi

29、ficance to Structural Performance? 如何根据它们对结构性能的重要性量化残余应力结果? n Tensile strength 拉伸强度 n Compression strength 压缩强度 n Fatigue 疲劳 n Fracture 断裂 n Other failure modes 其它失效方式 l Stress corrosion cracking 应力侵蚀裂纹 l Creep damage 蠕变破坏 38 焊接残余应力与变形 Equilibrium Based Residual Stress Decomposition Technique 基于平衡的残

30、余应力分解技术 39 焊接残余应力与变形 Contributions to Stress Intensity Factors as a Function of Crack Size 对应力强度因子的贡献作为裂纹尺寸的函数 40 焊接残余应力与变形 Observations 观察 n Decomposed components 分解的各部分 l Membrane and bending components are most important 膜和弯曲分量最重要 l Self-equilibrating components 自平衡分量 Much less important 不重要 Effe

31、cts limited to small cracks 影响仅限于小裂纹 41 焊接残余应力与变形 Length Scale Considerations in Residual Stress Analysis 残余应力分析中的尺度因素 n A boiler vessel shell repair weld 锅炉压力容器补焊 n Temper-bead repair 回火焊道修复（？） n Axial residual stress used for fracture assessment 用于裂纹评估的轴对称残余应力 n Detailed computational modeling 详细的

32、计算建模 n Deep hole residual stress measurements 深孔残余应力测量 42 焊接残余应力与变形 Microstructure Estimation Temper Bead Deposition 微观结构评估回火焊道熔敷 43 焊接残余应力与变形 Surface and Through-Thickness Residual Stress Distributions: Measurements versus Predictions 表面和厚度方向残余应力分布:测量与预测结果对比 44 焊接残余应力与变形 Length Scale Considerations

33、 in Residual Stress Analysis - Continued 残余应力分析中的尺度因素-续 45 焊接残余应力与变形 Comparison of Contributions of High-Order Self-Equilibrating Components to K 高阶自平衡分量对K贡献的比较 46 焊接残余应力与变形 Remarks 注意 n Consideration of length scale is important 考虑尺度因素很重要 n Any given residual stress distribution can be decomposed i

34、nto 任何一个给定的残余应力分布均可分解为 l Membrane 膜力 l Bending 弯曲 l Self-equilibrating 自平衡 l with a decreasing order of importance 按重要性不同的阶次的递减分解（?） n Higher order residual stress distributions (e.g., 2nd order) are not important in engineering assessment 高阶(如,2阶)残余应力分布在对工程评价中不重要 n An adequate resolution of the low

35、est order self-equilibrating component provides a length scale for both modeling and measurement considerations 最低阶自平衡分量的适当求解方案为建模和测量提供了尺度考虑 47 焊接残余应力与变形 Modeling Considerations 建模要考虑的因素 n Heat flow 热流 n Material high-temperature constitutive behavior 材料的高温本构行为 n Local and structural reactions durin

36、g welding and after 焊接过程中及焊后局部和整体结构的反应 48 焊接残余应力与变形 Heat & Fluid Flow 热及流体流动 n Weld pool dynamics too complicated to be practical 焊池动力学太复杂难于实现 n Equivalent conduction model is adequate 等效的传导模型已足够 49 焊接残余应力与变形 Welding Heat Flow Modeling Conduction Heat Transfer 焊接热流建模传导传热 n 3D FE analysis can still b

37、e very time consuming 三维有限元分析非常耗时 n Convergence is the big issue 收敛性是大问题 l Time/length scale relationship in transient thermal solution 瞬态热解中的时间/尺度关系 n More stringent mesh refinement is required than that for thermo plasticity analysis 需要比热塑性分析更严格的网格细化 n Most of residual stress solutions to date are

38、 based on 2D solutions 目前更多的残余应力解决方案是基于二维的解决方案 50 焊接残余应力与变形 Comments on 2D Heat Flow Models 二维热流模型讨论 n If the heat input is calculated based on actual welding parameters, significant overheating will result in a 2D model: 如果热输入是基于实际的焊接参数计算的，二维模型中就会出现明显 的过热问题(?) l Heat loss in the 3rd direction 第三个方向

39、上的热损失 l Lack of proper time definition 缺乏适当的时间定义 n Analytical based 3D heat flow solution with a 2D slice mapped onto 2D FE model is more straight forward 基于解析的3D热流解用2D片映射到2D有限元模型更直接（？） 51 焊接残余应力与变形 A simple but effective procedure for 2D and Axisymmetric models 一个对二维和轴对称模型简单而有效的过程 n Setup 5% above

40、melting temperature over the entire weld pass, and everywhere else room temperature 在整个焊道上温度设为高于熔化温度 5%,其它地方为室温 n Remove all the weld passes except the first pass 除第一道外，去掉所有的焊道 n Setup holding time for each pass according to an analytical moving heat source solution to achieve the same HAZ sizes 为达到

41、相同的热影响区，需要根据移动 热源的解析解为每条焊道设置持续时间 n Add the every weld pass sequentially 以此类推添加每条焊道 52 焊接残余应力与变形 Holding Time Determination Using 3D Moving Arc Analytical Solution 利用3D移动电弧解析法确定持续时间（？） n Step 1 Determine HAZ width based on welding parameters and material properties 第一步:基于焊接参数和材料属性确定热影响区宽度 n n n Step

42、2 Determine holding time based on HAZ width and peak heating temperature 第二步:基于热影响区宽度与最高温度确定持续时间 53 焊接残余应力与变形 Calculation Example: Estimated HAZ and 2D Model Hold Time 算例:计算HAZ和2D模型持续时间 焊接电流:300A Welding current: 300A 电压:28V Voltage: 28V 效率:0.8 Arc efficiency: 0.8 焊接速度:10mm/s Travel speed: 10mm/s 材料

43、:低碳钢 Material: low carbon steel 54 焊接残余应力与变形 Analytical Based Thermal Solutions (ABTS) are Highly Desirable 基于解析的热计算是非常渴望的 n Rosenthal solution as a basis 以罗森塔尔方法为基础 n Significant enhancements recently developed: 最近重大的改进 l Convective boundaries (e.g., finite thickness, cut-outs) 对流边界条件(如,有限厚度,切断) l

44、Thermal transients (e.g., start/stop) 瞬态热(如,开始/停止) l Curved welds 曲线焊接 l Multi-pass welds 多道焊接 l Joint types (e.g., T-fillet,.) 接头类型(如, T型角焊缝,.) 55 焊接残余应力与变形 Heat Flow Modeling A Simple, but Effective Approach (3D Analytical Solution) 热流建模简单但有效的方法（三维解析法） n Typical fusion and profile (geometry and si

45、ze) from macrographs as input (Rothenthal type solution) 从宏观形貌得到的典型熔合与轮廓（几何与尺寸）作为输入（罗森塔 尔典型方法） 56 焊接残余应力与变形 Analytical Based Thermal Solutions (ABTS) - Experimental Validations 基于解析的热分析实验验证 57 焊接残余应力与变形 CPU Comparison of FEA and Analytical-Based Thermal Solution Techniques 有限元法与解析法热分析CPU比较 58 焊接残余应力

46、与变形 1D Illustration Problem (Graphic vs FE solution) Welding-Related Thermo plasticity 1D问题（图解与有限元解）焊接相关的热塑性 59 焊接残余应力与变形 One Limitation of Conventional Finite Element Packages Seen in the 1D and 2D Examples 由1D、2D的例子看传统有限元软件包的局限 n Continuum and structural mechanics based FE codes are not intended t

47、o deal material state (e.g., from solid to liquid) change 基于连续体和结构力学的有限元法则不能用于处理材料状态的变化 （如，从固态到液态） n A material point going through melting or re-melting should lose memory (prior plastic strain annihilation) on cooling 经过熔化或再熔化的材料点将在冷却时丢掉一些记忆（之前的塑性应 变湮没）(?) n Among all phase change effects, melting

48、/re-melting effects are the most important in residual stress analysis 在所有的相变影响中，熔化和再熔化是在残余应力分析中影响最大的 n What should we do? 如何解决这个问题？ 60 焊接残余应力与变形 A Unified Weld Constitutive Model 使用统一的本构模型 61 焊接残余应力与变形 Relevant Thermoplaticity Phenomenon - 1D Illustration Problem (FE solutions) 相应的热塑性现象1D问题（有限元解） 6

49、2 焊接残余应力与变形 Thermomechanical Behavior during Welding and Effects on Residual Stress/Distortion 焊接过程中的热力行为及其对残余应力和变形的影响 n Melting and re-melting effects are of critical importance, particularly in using commercial codes 熔化和再熔化的影响是非常重要的，特别是在应用商业法规的时候 n Solid-state phase transformation effects are typi

50、cally localized and can be ignored to provide an upperbound prediction 固态相转变的影响在发生的局部，在进行上限预测时可以忽略 n Visco-elastic-plastic effects can be ignored 粘弹塑性的影响可以忽略 n Welding heat flow solutions only need to capture weld fusion pro if melting/remelting behavior is properly modeled in the weld constitutive

51、model. 如果熔化/再熔化在焊接本构模型里能够正确建模，焊接热流方法只 是用来确定焊接熔合轮廓的影响 63 焊接残余应力与变形 Residual Stress and Distortion Development: Edge Weld on Plate 残余应力和变形产生：板料卷边焊接 64 焊接残余应力与变形 Phase Transformation Effects on Residual Stresses - Microstructure Characterization 相变对残余应力影响微观结构牲 65 焊接残余应力与变形 Phase Transformation Effects

52、on Residual Stresses 相变对残余应力的影响 66 焊接残余应力与变形 Temperature-Dependent Material Behavior and Effects on Final Residual Stresses 随温度变化的材料行为及对最终残余应力的影响 n Phase transformation 相变 lSolid state 固态 lSolid to liquid or liquid to solid 固态到液态或液态到固态 n High-temperature material constitutive behavior 高温材料的本构行为 lHar

53、dening laws 硬化规律 lVisco-elastic and visco-plastic behavior 粘弹和粘塑性行为 lStress-strain curve 应力-应变曲线 67 焊接残余应力与变形 Is Kinematic Hardening Preferred in Residual Stress Prediction? 随动硬化是残余应力预测中首选的吗？ 68 焊接残余应力与变形 Melting/Remelting and Hardening Law Effects on Residual Stresses: 1-D Model Illustration 熔化/再熔化

54、和硬化规律对残余应力的影响:1D模型图示 69 焊接残余应力与变形 Temp Dependent Stress-Strain Curves Used for 2 Cr-Mo Narrow Gap Weld 用于21/4Cr-Mo窄间隙焊的随温度变化的应力-应变曲线 70 焊接残余应力与变形 Comparison of Residual Stress Predictions:Along Line A-A 残余应力预测对比:沿A-A线 71 焊接残余应力与变形 Some Remarks on Material Modeling 材料建模的几点注意事项 n Visco-elastic and vis

55、co-plastic effects? 粘弹性和粘塑性影响？ n Hardening law? 硬化规律？ n Solid state phase transformation and transformation plasticity effects? 固态相变和相变塑性的影响？ n Melting/remelting? 熔化和再熔化？ l What to do if using commercial FEA packages? 如果用商业有限元分析软件需要做什么？ n High temperature material properties? 高温材料属性？ l Thermal physi

56、cal 热物理特性 l Thermal mechanical, e.g., stress-strain curve as a function of temperature 热机特性， 如作为温度函数的应力-应变曲线 72 焊接残余应力与变形 Two Types of Welding-Induced Distortions in Welded Structures 焊接结构中焊接引起的两种变形 n Stable Type 稳定类型 n Unstable Type 非稳定类型 73 焊接残余应力与变形 Implications 结论 n Stable type 稳定类型 l Permanent

57、永久变形 l Cannot be corrected without plastic deformation 没有塑性变形的情况下不能进行矫正 l Thermoplasticity phenomenon 热塑性现象 Measurable from accuracy control point of view n Unstable type 非稳定类型 l Temporary/intermediate 暂时的/中间过程的变形 l Can exhibit different shape upon further disturbance and assembly conditions 进一步的干扰（

58、因素）或装配条件可使之呈现不同形状 l Thermoplasticity + structural instability 热塑性+结构不稳定性 l Difficult to measure quantitatively 难于定量测量 74 焊接残余应力与变形 Stable Distortions 稳定变形 n Global in length scale 长尺度的全局问题 n Thermoplasticity procedures: identical to those for RS analysis 热塑性过程：同残余应力分析 n Tack welds need to be model 需

59、要对预焊进行建模 n 3D analysis typically required 通常需要3D模型 n Weld sequence: important 焊接顺序: 重要 n Plate/shell models: more cost effective 板/壳模型：更节省计算成本 75 焊接残余应力与变形 Angular Distortions in T Fillet Weld T型角接头的角变形 n Structural steel A36 结构钢A36 n Plate element model 薄板单元模型 n Moving arc solution 移动电弧解（？） n Valid

60、ated by 3D solid model 通过3D模型验证 76 焊接残余应力与变形 Bifurcation Indications in Experimental Data - Local Buckling of Panel with Two Stiffeners 实验数据中分岔有两个加强筋的局部屈曲 n Buckling at t = 4.5, 6, and 8 屈曲在t=4.5, 6 和8处 n Critical heat input strongly depends on t 相变潜热严重依赖于t n （Longitudinal residual stress range is r