基于轮廓法测试惯性摩擦焊接头内部残余应力

采用轮廓法测试小尺寸镍基高温合金惯性摩擦焊接头的内部环向应力、中等尺寸惯性摩擦焊接头内部环向和轴向应力;分析惯性摩擦焊接头内部环向和轴向残余应力分布特征. 结果表明,轮廓法能测试小尺寸及窄小焊缝试件的内部残余应力,能反映出窄小焊缝内部的大梯度焊接残余应力全貌;惯性摩擦焊接头的环向应力沿轴向变化剧烈,沿环向分布均匀,沿厚度分布不均匀;焊缝中心位置外表层区域环向应力小于内表层区域环向应力;焊缝中心外表面轴向应力为压应力,而内表面轴向应力为拉应力,且轴向应力沿厚度呈线性变化.     

Internal residual stress measurement on linear friction welding of titanium alloy plates with contour method

The internal residual stress within a TC17 titanium alloy joint welded by linear friction welding (LFW) was measured by the contour method, which is a relatively new and destructive technique to obtain a full map of internal residual stress. The specimen was first cut into two parts; the out-of-plane displacement contour formed by the release of the residual stress was then measured; finally, taking the measured contour of the cut plane as the boundary conditions, a linear elastic finite element analysis was carried out to calculate the corresponding distribution of residual stress normal to the cut plane. The internal stress distribution of the TC17 titanium alloy LFW joint was also analyzed. The results show that the tensile residual stress in the TC17 LFW weld is mainly present within a region about 12 mm from the weld centerline; the peak tensile residual stress occurs at the weld centerline and reaches 360 MPa (about one third of the yield strength of TC17 alloy); within the weld zone of the TC17 LFW weld, the through-thickness stress is not uniform, and the internal stress is larger than that near the top or bottom surface.     

基于三维双塑性体摩擦副模型的FGH96高温合金管惯性摩擦焊数值模拟

基于弹塑性有限元理论,采用三维塑性体/塑性体摩擦副模型,考虑实际焊接过程中两侧工件散热条件的差异,建立了FGH96高温合金管惯性摩擦焊过程有限元模型,计算了焊接过程中瞬态温度场和轴向应力场的分布,研究了初始转速、顶锻力和转动惯量对接头温度场和飞边形貌的影响。模拟的飞边形貌与试验所得焊件误差仅为5%,验证模型的可靠性。模拟结果表明,惯性摩擦焊过程中,摩擦界面升温迅速,峰值温度可达1 335 ℃,塑性变形主要发生在距界面4 mm的区域内,该区域轴向温度梯度较大。摩擦界面附近压应力值从中心到边缘逐渐降低,界面边缘应力状态由压应力转变为拉应力,飞边根部由于挤压变形,存在压应力集中。提高初始转速和转动惯量均能增加焊接热输入,延长摩擦时间,提升峰值温度,增加飞边挤出量;加大顶锻力可提高机械能转化成热能的效率,缩短摩擦时间,增加轴向缩短量和飞边卷曲度。 创新点： 塑性体/塑性体有限元模型能够综合考虑接触面力的相互作用,采用更符合实际的三维双塑性体模型,对FGH96高温合金环形工件惯性摩擦焊过程进行了数值模拟。     

Measuring residual stresses in linear friction welded joints composed by dissimilar titanium

The Ti–5Al–2Sn–2Zr–4Mo–4Cr (Ti17) titanium alloy is the main material used in manufacturing blades and disks of aero engines, and it is always jointed with different microstructures for the design constraints. In this work, the residual stresses of linear friction welding of β Ti17 and α?+?β Ti17 are measured by contour method and the X-ray diffraction method. The welding-induced tensions were found to be greater on the β side than that on the α?+?β side, and had an obvious reduction in the weld centre. After the post weld heat treatment (PWHT) of 630°C for 3?h, all tensions on the β side relax to a very limited value while some new PWHT-induced compressions are found on the α?+?β side.     

压力对FGH96/GH4169高温合金惯性摩擦焊接头性能的影响

在惯性摩擦焊机上对FGH96/GH4169高温合金进行了焊接,焊后利用光学显微镜、扫描电镜以及拉伸试验机等设备分析了接头的微观组织形貌、显微硬度、拉伸性能及断口形貌. 结果表明,摩擦焊近界面处最高温度接近1 100 ℃,界面处温度超过强化相固溶温度. 焊缝区组织为细小的等轴晶粒,晶粒尺寸远小于母材,热力影响区发生了拉伸变形. 焊后接头热力影响区处的强化相部分重溶,接头界面细晶区的强化相完全重溶. 随压力增大,Co原子的扩散距离增加,接头室温抗拉强度和高温抗拉强度有所升高,断裂位置位于GH4169侧热力影响区,断裂形式为韧性断裂.     

电模拟惯性摩擦焊接技术

为适应摩擦焊接设备的发展,降低制造成本,在对惯性摩擦焊接过程运动学方程分析基础上,结合电模拟惯量技术,开发出了电模拟惯性摩擦焊接技术及设备. 结果表明,电模拟惯性摩擦焊接过程中各参数随时间的变化规律,以及惯量大小对焊接参数的影响规律,符合惯性摩擦焊接的一般规律. 相同惯量下,电模拟惯性摩擦焊接与机械惯量惯性摩擦焊接过程转速曲线变化趋势一致. 采用电模拟惯性摩擦焊接技术,所需惯量可以设定成大于系统基本惯量,也可以设定成等于或低于系统基本惯量,还可以补偿主轴机械摩擦阻力对焊接过程参数的影响.     

GH4169合金与FGH96合金惯性摩擦焊接头组织和力学性能

在主轴转速为650 r/min、转动惯量为340 kg·m2、焊接压力为450 MPa焊接参数下,实现GH4169与FGH96异质材料惯性摩擦焊接,并对焊后热处理的接头进行显微组织与力学性能分析.在焊接热-力耦合作用下,焊接接头不同区域的金相组织发生变化,晶粒出现不同程度的细化、变形,基体强化相出现不同程度的溶解、变形.焊接接头显微硬度呈山峰状分布特征,焊接接头室温抗拉强度平均值为1 366 MPa,高温抗拉强度平均值为1 176.7 MPa,在650℃,641 MPa条件下的平均持久寿命为215 h,焊接接头具有良好的综合力学性能.     

Transient behaviour of torque and process efficiency during inertia friction welding

ABSTRACT

Process efficiency is a crucial parameter for inertia friction welding (IFW). A new method is developed to determine the efficiency by comparing the workpiece torque used to heat and deform the joint to the total torque. Particularly, the former is measured by torque load cell attached to the non-rotating workpiece, while the latter is determined from the deceleration rate of flywheel. The efficiency measured for IFW of AISI 1018 steel is inputted into analytical heat balance calculation of the upset length and finite element thermo-mechanical modelling of the extruded flash profile. The calculated results are consistent with the respective experiment data. The transient behaviour of torque and efficiency is discussed based on the energy loss and the bond formation.     

Detection and analysis of basic variables during linear friction welding of GH4169 superalloy

By monitoring the line voltage and current of the driving motor during linear friction welding (LFW) of GH4169superalloy,the frictional power of the rubbing interface between two components to be joine...     

Electron microscopy characterization of the weld line zones of an inertia friction welded superalloy

Microstructure in the weld line (WL) zone produced by inertial friction welding has been studied for a series of RR1000–RR1000 welds using transmission electron and scanning electron microscopy. A fully recrystallised fine grain structure was found to form throughout the WL zone, characterized by straight and smooth grain boundaries, high energy status and modified grain boundary chemistry due to very fast cooling after welding. Very fine γ′ particles with unimodal size distribution were reprecipitated in the WL zone. The fine γ′ particles are spherical in shape, high in number density and characterized by an imbalanced chemistry, containing less Al, Ti, Ni, Ta γ′-forming elements but more Cr, Co, Mo γ-forming elements than all types of parent γ′ particles. As a result, a hard and strong WL zone was produced by the inertial friction welding.     

铝合金搅拌摩擦焊接头残余应力测试分析

采用小孔法研究厚2 mm的6061-T5铝合金搅拌摩擦焊对接接头残余应力的分布规律,分别测量接头处垂直、平行于焊缝的残余应力,并进行了计算分析。结果显示,搅拌摩擦焊接头残余应力在焊缝及其附近区域无论是垂直还是在平行焊缝方向的均承受压应力,且随小孔深度的增加而增加。垂直和平行于焊缝方向的残余应力呈现出周期性分布,且它们在前进侧的周期相比于后退侧较小;残余应力在焊缝两侧呈不对称分布,后退侧应力值较高,其残余应力峰值出现在后退侧轴肩作用区域边缘处,其值分别为93 MPa和100 MPa。     

惯性摩擦焊接头非对称性分析

应用无线测温系统和热电偶测温技术,试验测定了惯性摩擦焊旋转端和滑移端试件的温度场,探讨了惯性摩擦焊摩擦界面两侧温度分布的非对称性;统计分析了不同焊接条件下惯性摩擦焊试样焊接区域的几何特征及宏观形貌.结果表明,滑移端的温度及升温速率均高于旋转端,滑移端的轴向缩短量、飞边宽度以及热力影响区(TMAZ)宽度均大于旋转端.分析认为惯性摩擦焊摩擦结合界面两侧温度场的非对称性与焊接区域几何特征的非对称性紧密相连.     

2205不锈钢摩擦焊接头组织及残余应力分布

采用X射线衍射技术对2205双相不锈钢焊接界面残余应力进行测试,同时利用光学显微镜及电子背散射衍射技术(EBSD)对接头旋合区（RZ）、热机影响区（TMAZ）及热影响区（HAZ）微观组织进行分析。结果表明：接头轴向、径向残余应力均表现为压应力状态,呈单边V形分布,其中轴向残余应力峰值(－287 MPa)位于热机影响区(TMAZ)边缘,该区域α相和γ相在焊接过程中,在剪切及摩擦作用下,发生剧烈扭曲;而焊缝中心旋合区具有明显的动态再结晶特征,呈细小等轴晶状(3~4 μm),残余应力仅为在－15~－54 MPa。     

单晶DD3与细晶FGH4095高温合金摩擦焊接头组织

对单晶DD3与粉末细晶FGH4095高温合金摩擦焊接接头,采用光学显微镜及SEM-EDS分析了接头组织、焊合区成分变化及接头连接机理.结果表明,焊合区两侧材料均形成了动态再结晶晶粒;连接界面位于两侧动态再结晶晶粒之间;连接界面两侧合金元素发生了扩散;两侧动态再结晶晶粒均有向对方弓形凸入长大的趋势,通过形成共同晶粒,实现两种异质材料的连接;FGH4095侧的动态再结晶晶粒向DD3一侧长大的趋势较大.DD3与FGH4095摩擦焊接过程中发生了摩擦面转移,实际的摩擦变形主要在DD3摩擦带内部,接头组织变化梯度大.     

基于计算机模拟的钛合金线性摩擦焊接焊缝内部残余应力分析

基于轮廓法测量通过线性摩擦焊接的TC17钛合金接头内部残余应力是一个能够获得接头内部应力状况的全新破坏性技术。首先将试样切成两半;然后测量由于残余应力的释放而引起的平面轮廓的位移;最后将切面的测量轮廓作为边界条件,用线弹性有限元计算垂直于切割平面的残余应力。对TC17钛合金线性摩擦焊接接头的内部应力分布进行分析。结果表明,TC17线性摩擦焊接焊缝的拉伸残余应力主要集中在距离焊缝中心12 mm的区域内;拉应力峰值处于焊缝中心,达到360 MPa(约为TC17合金屈服强度的1/3);应力在厚度方向的分布是不均匀的,并且内部的应力大于邻近的顶部和底部表面的应力。     

Study of residual stress variation with depth of friction stir welded aluminium plates with different thicknesses

ABSTRACT

The residual stress may greatly vary through thickness due to the large temperature gradients and severe plastic deformation in depth for thick section friction stir welded plates. AA 2024-T351 plates with 6.5, 12 and 20?mm thicknesses were joined by friction stir welding to investigate the differences of residual stress variations with depth between thin and thick plates. The surface residual stresses were compared between the X-ray diffraction and contour measurements. Significant variations of stress peaks, root central residual stresses and widths of ‘M’ profiles were observed along the thickness for thick plates. The origins of the aggravated variations with depth were investigated from the temperature gradients and material flow variations through thickness.     

Effects of the friction stir welding process variants on residual stress

A high-strength aerospace aluminium alloy, 25?mm thick plate, has been friction stir welded using four different process variants. The process variants used were stationary shoulder single pass, conventional shoulder single pass, stationary shoulder dual pass and conventional shoulder dual pass. The goal of the reported work was to investigate effects of different process variants on residual stress. Defect-free welds were produced by all process variants. Through thickness average, longitudinal, residual stress in both as-welded and post-weld heat-treated conditions is reported.     

电子束焊接GH536合金残余应力分布小孔法测试

航空发动机许多高温合金结构需要采用电子束焊接制造,但目前对其焊后的残余应力分布状况研究较少。针对航空发动机GH536合金材料,采用小孔法对其电子柬焊接试板的残余应力分布趋势进行测试研究,试验结果表明,焊缝区存在较低的应力峰值,且应力分布符合传统规律。研究旨在为航空发动机构件的电子束焊接加工制造积累经验和性能数据。     

线性摩擦焊IN718接头微观组织与织构演变

不同工艺参数下对IN718高温合金进行了线性摩擦焊接试验,采用OM,SEM,EBSD等对接头微观组织与织构进行了表征.结果表明,在摩擦压力169 MPa、振幅3 mm、频率35 Hz、摩擦时间6 s参数组合下获得的接头质量相对较好,但在焊缝端部仍能发现氧化物和碳化物.焊缝区δ相完全溶解,残留少量NbN;而热力影响区δ相部分溶解,部分晶界发生液化并伴有Laves相的产生.焊缝区发生了充分动态再结晶,呈现为等轴细晶组织,并在剪切力的作用下出现了明显剪切织构C（100）[011],而热力影响区发生部分动态再结晶,形成了（335）[186]织构.