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对AM50镁合金进行了搅拌摩擦焊接实验,研究了各特征点的焊接温度场变化规律.结果表明:在搅拌摩擦焊接过程中,各特征点都经历了"加热-峰值-冷却"的过程,且各特征点的加热速度、冷却速度、峰值温度以及到达峰值温度的时间各不相同.在一定的旋转速度下,各特征点的峰值温度随焊接速度的减小而升高;而在一定的焊接速度下,各特征点的峰值温度随旋转速度的增大而升高. 相似文献
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为建立搅拌摩擦焊接工艺参数与响应参数的关系,利用热流分析模型系统研究了搅拌头旋转速度、焊接速度及接触系数发生变化时峰值温度和纵向力的变化趋势。分析结果表明:随着搅拌头旋转速度的增大,峰值温度上升,纵向力减小,但当旋转速度达到一定值后,两者均不发生明显变化;焊接速度的上升对峰值温度影响不大,但纵向力线性上升;接触系数的增大使峰值温度先增后降,而纵向力则是逐渐减小。 相似文献
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为了更好理解搅拌摩擦焊接(FSW)过程和合理选择焊接工艺参数,本文尝试将焊接工艺参数与响应参数相联系,利用FLUENT软件建立了FSW过程的热流分析模型,分析了搅拌头旋转速度和焊接速度发生变化时,峰值温度和纵向力的变化趋势。结果表明:随着搅拌头旋转速度的增大,峰值温度上升,纵向力减小,但旋转速度达到600r/min后,两者均不发生太大变化;随着焊接速度的增大,峰值温度变化没有明显规律,且其变动范围较小,但纵向力线性上升。研究结果可为铝合金FSW工艺参数的选择提供依据。 相似文献
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采用LF21铝合金研究了复合搅拌摩擦焊时焊接工艺参数(旋转速度、旋转半径)对焊接接头力学性能的影响.结果表明,当其它焊接参数一定时,焊点的力学性能随着搅拌头旋转速度的增加而增加,当搅拌头的旋转速度增加到1 200 r/min时,焊点的剪切力达到最大值为3.47 kN,随着搅拌头旋转速度的进一步增加,焊点的力学性能开始降低.改变旋转半径,焊点的力学性能随着旋转半径的增加而增加,当旋转半径达到0.5 mm时,焊点的剪切力达到最大值为3.47 kN,然后,随着旋转半径的继续增加,焊点的力学性能开始降低.LF21铝合金的复合搅拌摩擦点焊焊点的微观组织与直插式搅拌摩擦点焊不同的是,在塑性环的边上形成了一个由第二层塑性环形成的"耳朵形"区域. 相似文献
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LY12铝合金摩擦点焊工艺及力学性能 总被引:3,自引:0,他引:3
摩擦点焊是在搅拌摩擦焊基础上开发的一种新型固态连接技术.针对2 mm厚的LY12铝合金,研究了摩擦点焊过程中的焊接工艺参数对焊点成形及力学性能的影响.结果表明,当焊接时间一定,搅拌头旋转速度较高时,焊点的表面成形较好;随着搅拌头旋转速度的降低,焊点的表面成形逐渐变差.焊点的抗剪载荷随搅拌头旋转速度增加呈现出先增大后减小的趋势,当搅拌头旋转速度为950 r/min、焊接时间为8 s时,焊点的抗剪载荷达到最大值,为9.33 kN/点.焊点横截面的显微硬度测试结果表明,显微硬度沿匙孔中心呈高-低-较高-低-高的"W"形分布,最小值出现在热影响区,塑性区的显微硬度较高,但略小于母材. 相似文献
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Saad B.Aziz Mohammad W.Dewan Daniel J.Huggett Muhammad A.Wahab Ayman M.Okeil T.Warren Liao 《金属学报(英文版)》2018,31(1):1
This paper presents a new thermomechanical model of friction stir welding which is capable of simulating the three major steps of friction stir welding(FSW) process, i.e., plunge, dwell, and travel stages. A rate-dependent Johnson–Cook constitutive model is chosen to capture elasto-plastic work deformations during FSW. Two different weld schedules(i.e., plunge rate, rotational speed, and weld speed) are validated by comparing simulated temperature profiles with experimental results. Based on this model, the influences of various welding parameters on temperatures and energy generation during the welding process are investigated. Numerical results show that maximum temperature in FSW process increases with the decrease in plunge rate, and the frictional energy increases almost linearly with respect to time for different rotational speeds. Furthermore, low rotational speeds cause inadequate temperature distribution due to low frictional and plastic dissipation energy which eventually results in weld defects. When both the weld speed and rotational speed are increased, the contribution of plastic dissipation energy increases significantly and improved weld quality can be expected. 相似文献
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《Science & Technology of Welding & Joining》2013,18(3):232-238
AbstractThe 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. 相似文献
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Poly Crystalline Boron Nitride (PCBN) tool wear during the friction stir welding of high melting alloys is an obstacle to commercialize the process. This work simulates the friction stir welding process and tool wear during the plunge/dwell period of 14.8 mm EH46 thick plate steel. The Computational Fluid Dynamic (CFD) model was used for simulation and the wear of the tool is estimated from temperatures and shear stress profile on the tool surface. Two sets of tool rotational speeds were applied including 120 and 200 RPM. Seven plunge/dwell samples were prepared using PCBN FSW tool, six thermocouples were also embedded around each plunge/dwell case in order to record the temperatures during the welding process. Infinite focus microscopy technique was used to create macrographs for each case. The CFD result has been shown that a shear layer around the tool shoulder and probe-side denoted as thermo-mechanical affected zone (TMAZ) was formed and its size increase with tool rotational speed increase. Maximum peak temperature was also found to increase with tool rotational speed increase. PCBN tool wear under shoulder was found to increase with tool rotational speed increase as a result of tool’s binder softening after reaching to a peak temperature exceeds 1250 °C. Tool wear also found to increase at probe-side bottom as a result of high shear stress associated with the decrease in the tool rotational speed. The amount of BN particles revealed by SEM in the TMAZ were compared with the CFD model. 相似文献
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《Science & Technology of Welding & Joining》2013,18(1):42-46
AbstractThe present paper considers methods of calculation of maximum temperatures in welding using a constant welding speed and a point heat energy source. A comparison of theoretically obtained times for the occurrence of maximum temperatures with those obtained experimentally shows slight deviations. The latter are dependent only on the accuracy of temperature measurements and the workpiece size (i.e. plate size in the present work). In the present case, the limitations refer only to the workpiece size. The advantage of this new approach is in the determination of a plane curve which is an envelope of all the points in the workpiece that are simultaneously at the maximum temperature in arc welding. 相似文献
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A thermo-mechanical model is developed to predict the material deformations and temperature histories in the friction stir welding (FSW) process. Based on this model, the effects of the welding parameters on temperatures and material behaviors are investigated. Numerical results indicate that the maximum temperature in the FSW process can be increased with the increase of the rotating speed. The increase of the welding speed can lead to the obvious increase of the efficient input power for FSW system. The material particles on the top surface do not enter into the wake and just pile up at the border of the wake at the retreating side and this is the reason for the formation of the weld fash in FSW. Both the increase of the rotating speed and the decrease of the welding speed can lead to the increase of the stirring effect of the welding tool, which can improve the friction stir weld quality. But when the rotating speed is increased, the weld fash becomes more obvious. When the welding speed becomes higher, the rotating speed must be increased simultaneously to avoid any possible welding defects such as void. The simultaneous increase of the rotating and the translating speeds of the welding tool can lead to the increase of the residual stress. 相似文献
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以6061-T6铝合金与AZ31B镁合金为研究对象,基于Abaqus软件进行了异种材料搅拌摩擦焊过程的温度场数值模拟,重点分析搅拌针偏置镁侧下的搅拌区温度峰值影响焊缝表面成形的规律。结果表明,当焊接温度峰值高于Al-Mg共晶温度时,搅拌针根部附近区域会出现较明显的黏着现象,其随着焊接速度的降低而加剧,这与焊接温度峰值的升高相关。随着焊接速度的增加,焊缝表面更易避免裂纹缺陷的产生。当搅拌头的转速为1200r/min且焊接速度为40mm/min时,6061铝/AZ31B镁异种材料焊接接头的表面成形良好。 相似文献
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This study focuses on the effects of rotational and welding speeds on the microstructure and hardness of joints in friction stir welded single-phase brass. Welds were achieved under low heat input conditions at rotational and welding speeds of 400-800 r/min and 100-300 mm/min, respectively. In order to characterize the obtained welds, optical microscopy and Vickers hardness measurements were taken on the weld cross sections. According to the obtained results, increasing the welding speed and/or decreasing the rotational speed caused the grain size of the stir zone to decrease and, hence, improved the average hardness of this region. These results are discussed with respect to the interplay between the welding parameters and the peak temperature in the weld thermal cycle. 相似文献
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Silicon carbide particulate (SiCp) reinforced cast aluminium (Al) based metal matrix composites (MMCs) have gained wide acceptance in the fabrication of light weight structures requiring high specific strength, high temperature capability and good wear resistance. Friction stir welding (FSW) process parameters play major role in deciding the performance of welded joints. The ultimate tensile strength, notch tensile strength and weld nugget hardness of friction stir butt welded joints of cast Al/SiCp MMCs (AA6061 with 20% (volume fraction) of SiCp) were investigated. The relationships between the FSW process parameters (rotational speed, welding speed and axial force) and the responses (ultimate tensile strength, notch tensile strength and weld nugget hardness) were established. The optimal welding parameters to maximize the mechanical properties were identified by using desirability approach. From this investigation, it is found that the joints fabricated with the tool rotational speed of 1370 r/min, welding speed of 88.9 mm/min, and axial force of 9.6 kN yield the maximum ultimate tensile strength, notch tensile strength and hardness of 265 MPa, 201 MPa and HV114, respectively. 相似文献
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《Science & Technology of Welding & Joining》2013,18(7):553-562
AbstractA 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. 相似文献
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Rajesh Kumar Gupta Hrishikesh Das Tapan Kumar Pal 《Journal of Materials Engineering and Performance》2012,21(8):1645-1654
Friction stir welding (FSW), a promising solid state joining process invented at TWI in 1991, was used to join 9?mm thick 7475 aluminum alloy which is considered essentially unweldable by fusion processes. In the present work, the process parameters such as tool rotational speed were varied from 300 to 1000?rpm for a travel speed of 50?mm/min and the influence of process parameters in terms of energy input on microstructure, hardness, tensile strength, and the corrosion property of 7475 aluminum joints was evaluated and analyzed. The maximum tensile strength of FSW joints was obtained at rotational speed of 400?rpm and traverse speed of 50?mm/min (59.2?kJ) which attributed maximum stirred zone area and maximum hardness. The maximum corrosion resistance properties of weld in 3.5% NaCl solution, however, were obtained at rotational speed of 1000?rpm and traverse speed of 50?mm/min. Furthermore, for a given weld, stirred zone showed improved corrosion properties than TMAZ. 相似文献