共查询到20条相似文献,搜索用时 31 毫秒
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Luis TruebaJr Monica A. Torres Lucie B. Johannes Daniel Rybicki 《International Journal of Material Forming》2018,11(4):559-570
Self-reacting friction stir welding (SR-FSW), also called bobbin-tool friction stir welding (BT-FSW), is a solid state welding process similar to friction stir welding (FSW) except that the tool has two opposing shoulders instead of the shoulder and a backing plate found in FSW. The tool configuration results in greater heat input and a symmetrical weld macrostructure. A significant amount of information has been published in the literature concerning traditional FSW while little has been published about SR-FSW. An optimization experiment was performed using a factorial design to evaluate the effect of process parameters on the weld temperature, surface and internal quality, and mechanical properties of self-reacting friction stir welded aluminum alloy 6061-T6 butt joints. The parameters evaluated were tool rotational speed, traverse speed, and tool plunge force. A correlation between weld temperature, defect formation (specifically galling and void formation), and mechanical properties was found. Optimum parameters were determined for the welding of 8-mm-thick 6061-T6 plate. 相似文献
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为研究590 MPa级高强钢双面双弧工艺得到的焊接接头组织与性能的关系,采用钨极氩弧焊(TIG)与熔化极气体保护焊(MAG)方法获得成型良好的焊接接头,经过拉伸、冲击、弯曲试验及光学显微镜、扫描电镜、EBSD分析,对590 MPa级高强钢双面双弧立焊打底焊与盖面焊焊接接头的组织及性能进行了研究.结果表明:打底焊缝组织主要为贝氏体,盖面焊缝组织以贝氏体与针状铁素体为主;打底焊缝经历过一次热循环后组织得到一定程度的细化;打底焊缝硬度值与盖面焊缝相近,盖面焊缝热影响区最高硬度值高于打底焊缝热影响区最高硬度;2 mm坡口间隙性能较5 mm坡口间隙有较大提高,2 mm坡口间隙断口以韧窝断裂为主,5 mm坡口间隙断口以解理断裂为主. 相似文献
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本文分析了中厚板传统手工双面焊存在的诸如打底焊焊缝质量无法保证,需用碳弧气刨清根;工人劳动强度大;生产效率低;焊接质量不稳定等主要问题。为提高打底焊焊道质量,不用清根使背面得到良好的凹成形,研制了适合X形坡口的梯形体陶瓷衬垫。探讨了焊缝背面成形的主要影响因素及控制方法。 相似文献
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J. Bellmann J. Lueg‐Althoff S. Schulze M. Hahn S. Gies E. Beyer A.E. Tekkaya 《Materialwissenschaft und Werkstofftechnik》2019,50(8):883-892
Magnetic pulse welding is a promising technology for the joining of dissimilar metals. Since the input of thermal energy is significantly reduced compared to conventional fusion welding technologies, critical intermetallic phases can largely be avoided. Therefore, proper collision conditions are necessary. Those require a careful adjustment of the energetic and geometric parameters at the impact welding setup. The thickness of the accelerated joining partner (flyer) determines the necessary energy input for a successful weld. However, at the same time, it has an effect on the weld formation. This study utilizes a novel optical measurement system to explain these findings and to gain insights into the forming behavior of the flyer parts. It is shown that the collision angle depends on the flyer tube thickness and, thus, directly has an effect on the welding result. 相似文献
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在等离子弧搭接焊中,搭接焊接头的焊缝熔深是评价焊接质量的关键指标之一,而焊接过程中的热输入信息和熔池图像信息都与焊缝熔深有密切关系。本文通过建立304L不锈钢薄板等离子弧搭接焊数据采集系统,利用LabVIEW实时检测电信息,采用视觉传感技术实时获取薄板等离子弧搭接焊过程中的熔池图像,并通过图像处理方法获得熔池的几何参数信息,结合焊接工艺参数,选择峰值电流、峰值电压、焊接速度、离子气流量、保护气流量、熔池宽度和熔池后端长度作为输入量,焊缝熔深作为输出量,建立了基于支持向量机回归和BP神经网络的熔深预测模型。实验验证表明,采用径向基函数的支持向量机回归模型可以有效地对焊缝熔深进行预测,并具有很好的泛化能力,可为进一步实现在线优化焊接工艺参数提供依据。 相似文献
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Thermal efficiency is considered in connection with welding regimes and seam parameters by applying a statistical approach. This approach allows one to establish empirically (by fitting a mathematical model) the type of relationship that is present between performance characteristics and its influencing factors. Optimal regimes are found through thermal efficiency optimisation. The study leads to new proposals for the position of the focus with respect to the surface of the welded material, under conditions of maximum thermal efficiency or maximum welding depth. The values of the ratio of power to weld depth (P/H) and weld width times velocity of weld front (vB) are confirmed to be the main characteristic parameters of electron beam welding, considered as a self-organising process. 相似文献
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Friction taper stud welding is a new variant of friction welding which has been developed from the principles of friction hydro-pillar processing. This paper considers the effect of weld process parameters on weld defects, macrostructure and mechanical properties in AISI 4140 steel. It also presents 3D residual stress data for a typical friction taper stud weld. Applied downwards force, rotational speed and plunge depth (equivalent to consumable length) of the stud tool were systematically varied whilst measuring tool torque and temperature at several locations during welding. A simple Taguchi analysis was then used to relate process parameters and weld tensile strength. The combinations of parameters leading to high tensile strength are identified and linked to the occurrence of specific weld defects. 相似文献
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Quality Control of Spot Weldings by Acoustic Emission The quality control of spot weldings has to be performed continuously during welding. Acoustic Emission (AE) is a suitable method for online surveillance of the welding process. Several measuring parameters of AE are tested with regard to the characterization of the spot weld quality during the welding process. It is shown that the quality of the spot weld can be evaluated by measuring the energy of the AE signals during the welding process. This parameter can be applied also for controlling the welding time of each spot weld under constant current load. On the other hand, the quality of the spot welds can be estimated by measuring the AE count during cooling after finishing the weld spot. By this method the welding process can be controlled with regard to the tendency in the long run. 相似文献
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H.J. Zhang G.J. Zhang C.B. Cai H.M. Gao L. Wu 《Materials Science and Engineering: A》2009,499(1-2):309-314
A new high-efficiency method for welding thick plates of low-alloy high-tensile steel which does not require back chipping – double-sided arc welding (DSAW) – is provided in this paper. Backing run adopts double-sided pulse gas tungsten arc welding, and other passes adopt double-sided gas metal arc welding. Three-dimensional numerical models of DSAW with 50 mm plates are developed to predict the stress distribution by using finite-element analysis, computer parallel processing technology and multiple jobs design, and are compared with single arc welding (SAW). The analysis of the interpass stresses indicates that the stresses of the back and cover pass are to be regarded as the key point in multipass welding. To verify the calculated results, the residual stresses and transient temperature of back run weld measured individually agree approximately with the calculated results, which illustrates that the backing run and residual stresses of DSAW are lower than those of SAW. 相似文献
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Ultrasonic spot welding has received significant attention during past few years due to their suitable applications in comparison to conventional fusion welding techniques. Fusion welding of dissimilar Aluminum and Stainless steel alloys is always a challenging task because of poor control on grain size and formation of undesirable brittle intermetallic compounds in the weld metal, which have deleterious effect on mechanical properties. In the past, welding of dissimilar alloys has been performed using electron beam welding, laser beam welding and friction stir spot welding, resistance spot welding, etc. However, little work has been reported on dissimilar welding of Aluminum and Stainless steel alloys using ultrasonic spot welding. The objective of the present work is to optimize ultrasonic spot welding parameters for joining 3003 Aluminum alloy with 304 Stainless steel. Welding was performed at various clamping pressures (i.e. 30, 40, 50 and 60 psi) and energy levels for investigating its effect on microstructure, mechanical properties and bond quality of the weld. Different levels of weld quality i.e. ‘under weld’, ‘good weld’ and ‘overweld’ were identified at various welding parameters using physical attributes. The weld specimens prepared with energy 125 and 150 J showed the maximum bond strength and were rated as “good” weld. It was also revealed that for a good quality weld, the maximum tensile strength is achieved once a reasonable amount of bond density and material thinning (required for the formation of metallurgical bonds) is attained. 相似文献
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《Materials Science & Technology》2013,29(12):1069-1080
AbstractThe properties of a weldment are determined largely by the size and distribution of microstructural regions within the weld metal and heat-affected zone (HAZ). It has been appreciated for some time that these properties may be controlled by adjusting the parameters of the welding process, although until recently this was done mainly qualitatively. Means of achieving more quantitative control are now beginning to be applied. In this paper measurements of the sizes of the weld bead and HAZ are presented for single manual metal arc weld beads. The process variables investigated were electrode type, gauge size, welding position, polarity, welding current, preheat, and welding velocity. Functional relationships between the process variables and the size of the weld bead and HAZ are determined. The generality of these relationships is examined by analysing measurements made previously on other materials. The results are discussed in terms of the theory of the welding process and, as shown in two accompanying papers, they can be used to develop models of multipass manual metal arc welding on which a practical welding procedure may be based.MST/193a 相似文献
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Formability is a key factor which influences the friction weldability of dissimilar materials. Resistance to formability of
metals can be reduced by the electric induced plasticity under an external electric field. Friction welding of T2 Copper and
1Cr18Ni9Ti stainless steel was carried out under the electric fields with an attempt to improve the friction weldability of
these two materials. Effects of different types of external electric field on the microstructure of the welded joints were
investigated and distributions of the dominating elements in the weld zone were analyzed using EDX. Torsion strength of the
joints obtained from different welding parameters was tested. It was indicated that the dynamic recrystallization of the weld
metal was enhanced by the applying electric fields. For the specimen connected to the cathode of the power supply (referring
to negative field), much homogenous distribution of the recrystallized grains in the weld zone appeared. The diffusion distance
of the dominating elements increased under either an AC electric field or a negative field. The torsion strength of the welding
joints was improved with applying the external electric field, especially with the AC electric field. 相似文献
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Typical friction welds are made by holding a non-rotating sample in contact with a rotating sample under constant or gradually increasing pressure until the interface reaches the welding temperature and then stopping pressure rotating to complete the weld. This process requires additional time and is labor intensive. Recently, several control systems have been introduced to the industry for improving the welding process such as conventional automatic control, microcontroller control, and Programmable Logic Controller (PLC). However, these processes have limitations either on materials selection or on visualization. In this study, continuous monitoring, control and recording are implemented. Computer-controlled platform for the simulation and control of mechanisms is based on a Microsoft Visual Basic environment. Welding parameters such as friction time, forge time and breaking time are entered with a keyboard and can be saved and used again. To show the feasibility and versatility of the study, the evaluation is used for sample joining. It has been observed that this system works successfully and gives good performance. 相似文献
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Stainless steel 321 is a stabilized austenitic grade that prevents the formation of chromium carbides at the grain boundaries and subsequently reduces the risk of corrosion attack at the weld surface by forming titanium carbide. It is primarily used in industries such as pressure vessels, boilers, nuclear reactors, carburetors and car exhaust systems. In order to assess the effect of gas tungsten arc welding process parameters on weld penetration, the proposed Taguchi L9 orthogonal matrix has been selected with two factors and three levels for welding austenitic stainless steel 321 by adjusting the welding current and welding speed. Bead-on-plate experiments were performed on base metal of 6 mm thick plate by changing the process parameters, and corresponding weld bead measurement and macrostructure images are examined. Maximum depth of penetration −3.3017 mm is achieved with a heat input −1.4058 kJ/mm, i. e., welding current-220 A and welding speed-120 mm/min. Double-side arc welding technique is used to obtain full penetration on 6 mm thick plate. The quality of the weldment was assessed using non-destructive radiography inspection. Mechanical integrity and microstructural characteristics of the weldments were studied using tensile (transverse and longitudinal), bend, impact, microhardness, optical microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction analysis, ferrite number measurement and scanning electron microscope. The results reveal that the double side-tungsten inert gas weldment have better mechanical properties. It is corroborated from the weld metal microstructure that it contains γ-austenite, δ-ferrite and titanium carbides (intermetallic compounds). X-ray diffraction analysis and energy dispersive x-ray spectroscopy plots confirm the increase in the ferrite phase in weld metal. The ferrite measurement results show that the ferrite volume in the base metal and weld metal is 1.2 percent and 6.1 percent respectively. In addition, the higher δ-ferrite volume in the weldment helps in attaining superior mechanical integrity. Fractography shows that the failure mode of the weld metal and the base metal is ductile. 相似文献