Orbital friction stir lap welding in tubular parts of aluminium alloy AA5083

In this study, orbital friction stir lap welding of 360?mm diameter AA5083-H321 tube to 350?mm diameter AA5083-O flange was investigated. The influence of rotational and travel speed of tool with triangular frustum pin on the metallurgical structure and mechanical properties of orbital friction stir lap welded samples were studied. The results indicated that defect free orbital lap joints are successfully obtained using tool rotational speed of 650 and 800?rev?min^?1 with a constant travel speed of 40?mm?min^?1. The strengthening mechanism in the stir zone is solid solution strengthening and dislocation looping. The maximum joint strength was achieved at a welding speed of 650?rev?min^?1 and 40?mm?min^?1. Failure of tensile shear test samples occurred far from the friction stir welding zone.     

铝合金搅拌摩擦焊插入工艺参数对轴向力和扭矩的影响

搅拌摩擦焊接(FSW)插入阶段获得的轴向下压力和旋转扭矩是衡量FSW焊机静态性能的重要指标。为了降低插入尾部阶段的轴向下压力和扭矩,对6013铝合插入阶段工艺参数和产生的轴向力及扭矩之间的关系进行了试验研究,插入阶段最大轴向力和最大扭矩几乎同时出现在插入的尾段,保证探头旋转速度Rp不变、减小插入速度vp、保证vp不变、增加Rp,可以降低最大轴向力Pzmax和最大扭矩Czmax。工艺参数通过插入过程的热输入能量影响工件的温度、状态,从而影响Pzmax和Czmax。     

Tool design and stir zone grain size in AZ31 friction stir spot welds

Abstract

The influence of tool design and tool rotational speed variations on the torque, energy output, stir zone temperature and average grain size in the stir zones of AZ31 friction stir spot welds was investigated. The average stir zone grain size decreased by ～1 μm in AZ31 friction stir spot welds made using a three-flat/threaded tool design and tool rotational speeds of 2250 and 3000 rev min^?1. However, there was no statistically significant influence of tool design on the average grain sizes in friction stir spot welds made using tool rotational speeds of 1500 and 1000 rev min^?1. There was no evidence of grain growth in the stir zones of AZ31 friction stir spot welds. Similar torque, calculated energy output and stir zone temperature values were found in AZ31 friction stir spot welds made using threaded and three-flat threaded tool designs and tool rotational speeds from 1000 to 3000 rev min^?1.     

Temperature and force response characteristics of friction stir welding on Invar 36 alloy

Abstract

The temperature and force response during friction stir welding of Invar 36 alloy were investigated by experimental measurement and numerical simulation. The effect of welding parameters was studied. The temperature and force characteristics were roughly discussed. It is indicated that an elevation rotational speed results in increasing temperature and decreasing axial force, whereas rotational speed has no obvious influence on the longitudinal force. An elevation travelling speed produces increasing axial force and longitudinal force, and a decreased trend of temperature out of stir zone centre. Friction stir welding of Invar 36 alloy produced relatively high peak temperatures, high axial and longitudinal forces, and a narrow temperature distribution compared with those of the other reported high melting temperature materials.     

Two experimental set-ups designed for investigation of friction stir spot welding process

Abstract

The effects of positioning and clamping conditions of a specimen of friction stir spot welding are investigated in this paper in terms of axial force and torque generated during the process. For this purpose, two special designs of experimental set-ups embedding different positioning and clamping conditions are presented. A four-component mechanical sensor is used for the measurements. First, the effects of the rotational speed of the spindle and the plunge depth of the tool on the axial force and torque are studied. Second, the effects of positioning and clamping conditions are investigated through both set-ups designed, varying the spindle rotation speed. It is shown that the axial force and torque exhibit an important dependence with respect to the rotation speed of the tool and that their maxima depend on positioning and clamping conditions of the specimen.     

Experimental and thermomechanical analysis of friction stir welding of poly(methyl methacrylate) sheets

In the present work, the feasibility of friction stir welding (FSW) of poly(methyl methacrylate) sheets was studied experimentally and theoretically by employing thermomechanical simulations. The effect of processing parameters including tool plunge depth, tilt angle, tool rotational speed (w), and transverse velocity (v) was investigated to determine suitable conditions to attain sound and defect-free joints. It is shown that a low tool plunge depth of 0.2?mm and a tilt angle of 2° provide suitable material flow to gain sound joints. By controlling the heat input into stir zone by increasing the tool rotational speed and decreasing linear velocity, the formation of defects can be minimised. Mechanical examinations in both longitudinal (LS) and transverse (TS) directions indicate that the highest joint strength of 57?MPa (for LS) and 42?MPa (for TS) are obtained at processing conditions of w?=?25?mm?min^?1 and v?=?1600?rev?min^?1. The measured tensile strengths are 81 and 60% of the base polymer, respectively.     

Influence of tool design on mechanical properties of AZ31 friction stir spot welds

Abstract

The influence of tool design on the energy output, microstructural features and overlap shear strength properties of friction stir spot welds made of AZ31 base material is examined. The mechanical properties of AZ31 friction stir spot welds made using three-flat/threaded tools are superior to those in joints made using a tool with a threaded pin at all tool rotational speed settings. It is proposed that the failure load properties are optimised when the friction stir spot welding operation is carried out in such a manner that it produces a large bonded width, a small v/t ratio (the height of the hook region above the sheet intersection divided by the thickness of the upper sheet) and a hook region, which is curved outwards from the tool axis.     

Influences of welding parameters on mechanical properties of AZ31 friction stir spot welds

Abstract

In this study, the influence of welding parameters, including tool rotational speed, plunge rate and dwell time, on the overlap tensile shear properties of AZ31 friction stir spot welds was investigated. The microstructures in stir zones and fracture surfaces were observed using optical microscope and scanning electron microscope respectively. The bonded width and h value (the distance from the tip of the partially bonded region to the top of the weld surface) were measured. The results indicated that larger bonded width and higher h value of the AZ31 weld result in better mechanical property. It is proposed that high tensile shear loads are produced when the tool rotational speed range of 1500–2250 rev min^?1 and 1 s dwell time are applied during the friction stir spot welding of AZ31. The plunge rate range from 2·5 to 10 mm s^?1 has insignificant influence on the tensile shear load of AZ31 joints under the present conditions. The failure mode changes from interfacial to pullout when the tool rotational speed is >2250 rev min^?1. The fracture feature of AZ31 welds is brittle fracture.     

Analysis of process parameters effects on dissimilar friction stir welding of AA1100 and A441 AISI steel

Abstract

A prominent benefit of friction stir welding process is to join plates with dissimilar material. In this study, an attempt is made to find effects of tool offset, plunge depth, welding traverse speed and tool rotational speed on tensile strength, microhardness and material flow in dissimilar friction stir welding of AA1100 aluminium alloy and A441 AISI steel plates. Here, one factor at a time experimental design was utilised for conducting the experiments. Results indicated the strongest joint obtained at 1·3?mm tool offset and 0·2?mm plunge depth when the tool rotational speed and linear speed were 800?rev min^??1 and 63?mm min^??1 respectively. The maximum tensile strength of welded joints with mentioned optimal parameters was 90% aluminium base metal. Fracture locations in tensile test at all samples were in aluminium sides. Owing to the formation of intermetallic compounds at high tool rotational speed, the microhardness of joint interface goes beyond that of A441 AISI steel.     

Optimisation of friction stir welding process parameters to weld cast aluminium alloy A413 – an experimental approach

Abstract

A413 is a high strength eutectic aluminium silicon cast alloy used in the food, chemical, marine, electrical and automotive industries. Fusion welding of these cast alloys can lead to problems such as porosity, microfissuring and hot cracking, etc. However, friction stir welding can be used to weld these cast alloys effectively, without defects. In this investigation, an attempt was made to optimise the friction stir welding process parameters for joining the cast aluminium alloy A413. Joints were made using four levels each of tool rotation speed, welding speed and axial force. The quality of the weld zone was analysed using macrostructure and microstructure analysis. Tensile strength of the joints were evaluated and correlated with the weld zone hardness and microstructure. The joint fabricated using a tool rotation speed of 900 rev min^?1, a welding speed of 75 mm min^?1 and an axial force of 3 kN showed the best tensile strength.     

AA5083铝合金的搅拌摩擦焊接工艺参数对搅拌头受力和热输入的影响(英文)

采用系统实验设计方法研究AA5083铝合金搅拌摩擦焊接工艺参数对搅拌头受力和热量输入的影响,得到了用来设计搅拌摩擦焊搅拌头和焊机的经验模型。当采用计算机来控制搅拌摩擦焊接时,这些模型可用来确定AA5083这类铝合金的摩擦焊接工艺参数、编制焊接程序及工艺参数控制。结果表明:影响轴向力和热量输入的重要参数是搅拌头转速、焊接速度和搅拌头轴肩直径,而影响纵向应力的重要参数是焊接速度和探头直径。     

Process–structure–property relationships for nugget and heat affected zone regions of AA2524–T351 friction stir welds

Abstract

The effects of weld tool rotational speed ω, welding speed v and z-axis force F_Z during friction stir welding of the aluminium alloy 2524-T351 on the resulting process response variables, nugget microstructure, nugget tensile properties and heat affected zone hardness variations were investigated. For the range of conditions examined, the results indicate that ω has the dominant effect on nugget properties and structure, that optimum nugget tensile properties can be obtained by increasing ω to obtain a peak temperature that is just below the incipient local melting temperature, and that excessive values of ω result in low nugget ductility because of localised embrittlement near the weld crown. The study has also shown that the peak weld temperature is inversely related to the measured torque T ₀. The T ₀–ω relationship appears to be a useful guide for weld modification, as it is indicative of conditions leading to overheating in the nugget region.     

Process parameters optimization for friction stir welding of RDE-40 aluminium alloy using Taguchi technique

Taguchi approach was applied to determine the most influential control factors which will yield better tensile strength of the joints of friction stir welded RDE-40 aluminium alloy. In order to evaluate the effect of process parameters such as tool rotational speed, traverse speed and axial force on tensile strength of friction stir welded RDE-40 aluminium alloy, Taguchi parametric design and optimization approach was used. Through the Taguchi parametric design approach, the optimum levels of process parameters were determined. The results indicate that the rotational speed, welding speed and axial force are the significant parameters in deciding the tensile strength of the joint. The predicted optimal value of tensile strength of friction stir welded RDE-40 aluminium alloy is 303 MPa. The results were confirmed by further experiments.     

铝合金2024-M搅拌摩擦焊接头性能

通过轴向拉伸试验,研究了搅拌针旋转速度对铝合金2024-M接头力学性能的影响.结果表明,轴向拉伸断裂部位随搅拌针转速的变化而变化,高转速下接头组织中有大量块体颗粒被保留下来,降低了接头强度,断裂发生在焊核区;低转速下因轴肩与焊接材料间摩擦机制作用在接头成形中的比例减小,层间结合力减弱,接头断裂面呈现层状结构,焊核区又成为断裂的敏感部位;当焊接速度为20 mm/min时,搅拌针转速存在一个理想的焊接参数范畴,在这个焊接参数范畴内焊接的试样断裂通常发生在母材区,断裂面与拉伸轴成45°,属典型的剪切断裂.     

Structural evolution and superplastic formability of friction stir welded AA 2095 sheets

Friction stir welding was used to join superplastic AA 2095 sheets. The effect of welding rate on the grain size distribution and grain boundary misorientations in the stir zone was investigated. The superplastic behavior of the weld nugget parallel to the welding direction was also characterized at 495 °C and strain rates from 10⁻⁴s⁻¹ to 10⁻²s⁻¹. Increasing the welding rate during friction stir welding augmented the formation of a fine-equiaxed high-angle grain boundary structure within the stir zone. Increasing intensity of plastic straining during friction stir welding resulted in enhanced properties during subsequent superplastic formation. The maximum strain-to-failure was obtained for the weld made at a tool speed of 1000 rpm and a weld rate of 4.2 mm/s when tested at a superplastic forming strain rate of 10⁻³s⁻¹.     

Periodic variation of torque and its relations to interfacial sticking and slipping during friction stir welding

Abstract

The fraction of slipping between the tool and the workpiece during friction stir welding was calculated based on the measured torque and axial force with a sampling frequency of 1000 Hz. The results showed that the torque and fraction of slipping present a variation with the same periodicity that is equal to the time of one tool rotation. A model was proposed to present the average slipping fraction under different process parameters. The variation of the contact condition between the tool and the workpiece in one rotation was explained.     

Numerical and experimental investigation on friction stir lap welding of aluminium to steel

Use of multimaterial fabrication such as aluminium to steel to reduce overall vehicular body weight has gained significant attention in the automotive industries. Since fusion welding of aluminium to steel is difficult, friction stir welding of the same is considered as an effective recourse. Quantitative studies on friction stir welding of aluminium to steel are thus important but scarce in the literature. We present here a numerical and experimental study on friction stir lap welding of AA6061 to high strength interstitial free coated steel sheets under different combinations of tool rotational speed and welding speed. The computed values of thermal cycle, torque and traverse force are found to be in good agreement with the corresponding experimentally measured values. The computed thermal cycles along the AA6061 to steel interfaces are related qualitatively with the experimentally measured trend and distribution in Fe–Al intermetallics along the weld joint interface.     

Impact of process parameters during friction stir welding of AZ80A Mg alloy

In this paper, the influence of friction stir welding process parameters and impact of tool geometry on the microstructural characteristics and tribological properties of AZ80A magnesium alloy are experimentally investigated. Tool with three different pin profiles at a constant tool rotational speed ω to feedrate υ ratio were employed. Additionally, detailed experimental measurements are also carried out on the hardness and wear losses of joints. The chemical compositions of fabricated joints are analysed using energy dispersive spectrometry. The taper cylindrical pin profiled tool exhibited sound joints under the 750?rev?min^??1/75?mm?min^??1 ratio. It is also found that the tool rotational speed plays a more significant role on the microstructural characteristics and mechanical properties of the joints, compared to feedrate.     

超声辅助搅拌摩擦焊温度场及残余应力场分析

超声辅助搅拌摩擦焊是一项在搅拌摩擦焊的搅拌头上添加轴向高频振动的新技术. 以6 mm厚7075铝合金材料为研究对象,建立了超声辅助搅拌摩擦焊与普通搅拌摩擦焊接的热源模型,通过ANSYS软件研究了轴向振动对焊接过程温度场以及焊后残余应力的影响规律. 结果表明,轴向振动的添加能够增大热输入量,提高焊接峰值温度且降低焊缝残余应力;在相同转速及焊接速度下,当振动频率一定时,焊接峰值温度和焊后残余应力随着振动幅值的增加而增大;当振动幅值一定时,随着振动频率的增大,焊接峰值温度及焊后残余应力也相应增加.     

基于钻铣床的搅拌摩擦焊设备设计

以ZX50CA钻铣床为研究对象,采用液压技术对其压下装置进行设计,设计出一台适用于镁合金薄板搅拌摩擦焊的设备,选用3 mm厚的AZ31镁合金板材进行对接焊接实验。结果表明:当搅拌头转速为1400 r/min、焊接速度为15 mm/min、压紧力为1500 N时,焊接接头表面成形良好。通过实验证明,该设备能够满足搅拌摩擦焊的工艺参数要求,适用于搅拌摩擦焊的实验研究,而且相对于大型专用搅拌摩擦焊设备,成本低,使用灵活、方便,为镁合金薄板搅拌摩擦焊设备的开发提供了很好的参考价值。