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对铝合金3003进行一系列的搅拌摩擦搭接焊试验,并对焊接接头的工艺及组织性能进行了分析。试验结果表明:焊接接头可分为3个区域:焊核区、热机械影响区和热影响区,各区域的组织有明显的特征。当搅拌头的旋转速度为1120 r/min,焊接速度为50mm/min时,焊缝成型良好,当焊接工艺参数选择不恰当时,会产生飞边、沟槽、隧道型缺陷、钩状缺陷及波浪状曲线等缺陷。同时该旋转速度下各焊接速度所对应的抗拉强度普遍较高,基本可以达到母材抗拉强度的75%以上。在搭接焊核区硬度较高,有的甚至超过母材,在上板前进侧的热影响区硬度达到最低值。 相似文献
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采用搅拌摩擦焊对异种铝合金6061-T6(上板)和A356-T6(下板)进行搭接焊,用体式和光学显微镜观察搭接接头的组织形貌,并测试其显微硬度.结果表明:在适当的工艺参数条件下,可以获得表面成形良好、内部无明显缺陷的搭接接头.在焊核区,两板间存在明显的界面,且位置较原位置整体上移,前进侧界面处呈锯齿状,界面由两种铝合金组织交替镶嵌而成,而后退侧界面则呈曲线状.两板均呈现典型的搅拌摩擦焊接头组织:焊核区由细小的等轴晶组成,而热影响区组织与母材相似,晶粒有细微粗化,热机影响区晶粒被拉长、弯曲,有明显的塑性流动.两板焊缝区显微硬度比各自母材均有不同程度的降低,且上板6061-T6降低幅度较大,焊后最大硬度约为母材的65%. 相似文献
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采用激光填丝焊对6063铝合金进行焊接,并对焊接接头进行人工时效和固溶+人工时效的热处理。通过光学显微镜、扫描电镜观察及拉伸试验,对焊后经不同热处理的焊接接头组织和性能进行研究。结果表明:未热处理的焊接接头抗拉强度为196 MPa,焊缝内部为铸态组织,弥散分布着Mg2Si强化相,熔合线附近存在向焊缝内部生长的粗大柱状晶,焊缝内部为细小的树枝晶,焊缝中心为等轴晶;经时效处理后,焊接接头组织不均匀性和强化相的分布得到改善,焊接接头抗拉强度提高27 MPa;经固溶+时效处理的焊接接头抗拉强度提高64 MPa,焊缝组织、熔合区及热影响区组织得到显著细化。焊接接头均为韧脆混合断裂;时效处理的断口韧窝大小差异较大,韧窝较深;固溶+时效处理后的断口韧窝大小均匀,韧窝尺寸较大较深,韧窝数量更多。 相似文献
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Michael Regev Tal Rashkovsky Marcello Cabibbo Stefano Spigarelli 《Journal of Materials Engineering and Performance》2018,27(10):5054-5063
The poor weldability of the AA2024 aluminum alloy limits its use in industrial applications. Because friction stir welding (FSW) is a non-fusion welding process, it seems to be a promising solution for welding this alloy. In the current study, FSW was applied to butt weld AA2024-T3 aluminum alloy plates. Creep tests were conducted at 250 and at 315 °C on both the parent material and the friction stir welded specimens. The microstructures of the welded and non-welded AA2024-T3 specimens before and after the creep tests were studied and compared. A comprehensive transmission electron microscopy study together with a high-resolution scanning electron microscopy study and energy-dispersive x-ray spectroscopy analysis was conducted to investigate the microstructure stability. The parent material seems to contain two kinds of Cu-rich precipitates—coarse precipitates of a few microns each and uniformly dispersed fine nanosized precipitates. Unlike the parent material, the crept specimens were found to contain the two kinds of precipitates mentioned above together with platelet-like precipitates. In addition, extensive decoration of the grain boundaries with precipitates was clearly observed in the crept specimens. Controlled aging experiments for up to 280 h at the relevant temperatures were conducted on both the parent material and the welded specimens in order to isolate the contribution of exposure to high temperatures to the microstructure changes. TEM study showed the development of dislocation networks into a cellular dislocation structure in the case of the parent metal. Changes in the dislocation structure as a function of the creep strain and the FSW process were recorded. A detailed creep data analysis was conducted, taking into account the instability of the microstructure. 相似文献
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采用电化学腐蚀和浸泡腐蚀试验对双轴肩搅拌摩擦焊AA2219-T87型铝合金的不同区域进行了腐蚀研究。结果表明,焊缝区具有最高的耐腐蚀性,母材的耐腐蚀性最差。母材中析出相的体积分数最高,越靠近焊核,析出相回溶数量越多。焊核区由细小的等轴晶组成,只存在少量θ相 相似文献
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Microstructures and Mechanical Properties of Friction Stir Spot Welded Aluminum Alloy AA2014 总被引:1,自引:0,他引:1
S. Babu V. S. Sankar G. D. Janaki Ram P. V. Venkitakrishnan G. Madhusudhan Reddy K. Prasad Rao 《Journal of Materials Engineering and Performance》2013,22(1):71-84
Friction stir spot welding (FSSW) is a relatively recent development, which can provide a superior alternative to resistance spot welding and riveting for fabrication of aluminum sheet metal structures. In the current work, FSSW experiments were conducted in 3-mm thick sheets of aluminum alloy 2014 in T4 and T6 conditions, with and without Alclad layers. The effects of tool geometry and welding process parameters on joint formation were investigated. A good correlation between process parameters, bond width, hook height, joint strength, and fracture mode was observed. The presence of Alclad layers and the base metal temper condition were found to have no major effect on joint formation and joint strength. Friction stir spot welds produced under optimum conditions were found to be superior to riveted joints in lap-shear and cross-tension tests. The prospects of FSSW in aluminum sheet metal fabrication are discussed. 相似文献
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以ER5183、ER5356与ER5556为填料,利用气体保护钨极电弧焊对A7075与A7050高强度铝合金进行异质焊接,焊接后再施以人工时效(T1)、固溶处理+不完全人工时效(T5)及固溶处理+完全人工时效(T6),研究不同热处理方式对其接头微观结构的影响.由金相显微观测可知,经T5与T6热处理后会有大量析出物出现在热影响区晶粒内部与晶界处,并产生沿晶破裂的现象.由断裂面微镜观观测可知,经T1热处理后合金样品的破裂面为韧窝状组织,属于延性破坏;而经T6热处理后破裂面的部分区域仍保持韧窝状组织,但也有部分区域转变为脆性破坏. 相似文献
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M.T. Milan W.W. Bose Filho J.R. Tarpani A.M.S. Malafaia C.P.O. Silva B.C. Pellizer L.E. Pereira 《Journal of Materials Engineering and Performance》2007,16(1):86-92
The main aim of this study was to evaluate the residual stress field in friction stir welded joints of 2024-T3 aluminum alloy
plates using the slitting method. This is based on the fact that when a cut, simulating a growing crack, is incrementally
introduced into a part, residual stresses are relieved on the slot surfaces created, causing the part to deform. Such deformation
can be measured by strain gages attached to specific regions of the part and the residual stress profile that originally existed
can be evaluated. Cuts were introduced by wire electro discharge machining (WEDM), in finishing mode, either perpendicularly
or longitudinally to the weld nugget, in 3.2 × 60 × 120 mm3 rectangular testpieces. For the longitudinal testpieces, the slot was introduced in two different positions: on the center
of the weld nugget and 5 mm distant from the weld center line, in order to sample the thermomechanically/heat affected zone.
The residual stress intensity factor, K
r, was calculated using a fracture mechanics approach and the inverse weight function method was employed to obtain the initial
residual stress profile. Residual stress redistribution profiles ahead of the slot tip could also be derived using the inverse
weight function method. However, for cracked components subjected to compressive residual stress fields, when the crack faces
are in contact, a non-linear problem arises and the zero displacement condition has to be taken into account in order to provide
a more accurate solution of the residual stress field. 相似文献
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In order to study the effect of friction stir welding (FSW) on corrosion resistance of Al-Cu-Li alloy AA2099-T8, the microstructure and microhardness of FSW joints were characterized, and then, the corrosion behavior of the FSW joints was investigated by the immersion and potentiodynamic polarization tests in a 3.5% NaCl solution at room temperature. It is indicated that the alloy was softened by FSW, with the lowest hardness appearing at the boundary between the nugget zone and the thermo-mechanically affected zone. When exposed to the NaCl solution, the FSW joint was characterized by shallow pits and was free of severe localized corrosion, probably due to dissolution of T1 (A2CuLi) phase in the FSW joint. It is suggested that further work should be carried out to evaluate the galvanic coupling effect between the FSW joint and the base metal, as well as the stress corrosion cracking resistance of the FSW joint. 相似文献
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Underwater friction stir welding (FSW) has been demonstrated to be available for the improvement in tensile strength of normal
FSW joints. In order to illuminate the intrinsic reason for strength improvement through underwater FSW, a 2219 aluminum alloy
was underwater friction stir welded and the homogeneity of mechanical properties of the joint was investigated by dividing
the joint into three layers. The results indicate that the tensile strength of the three layers of the joint is all improved
by underwater FSW, furthermore, the middle and lower layers have larger extent of strength improvement than the upper layer,
leading to an increase in the homogeneity of mechanical properties of the joint. The minimum hardness value of each layer,
especially the middle and lower layers, is improved under the integral water cooling effect, which is the intrinsic reason
for the strength improvement of underwater joint. 相似文献
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6082-T6为轨道、汽车等产品常用的高强度可热处理强化铝合金材料,其接头焊后会存在过时效软化的现象进而使焊接接头强度降低。本实验采用单脉冲MIG焊的焊接方法使用5087焊丝进行焊接,焊态接头抗拉强度为212 MPa,焊接接头硬度最低值为69 HV,位于距离焊缝中心7 mm的热影响区(HAZ)。在对焊接接头实施540 ℃×40 min+175 ℃×8 h的热处理制度后,其焊接接头抗拉强度为283 MPa,提升了71 MPa,焊接接头硬度最低值为100 HV,位于焊缝金属区(WZ)。 相似文献
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Microstructure and Properties of Friction Stir Welded Joints of Al-Mg-Sc Alloy Plates 总被引:1,自引:0,他引:1
采用搅拌摩擦焊对铝镁钪合金热轧板和冷轧-退火板进行焊接。测定焊接接头的硬度分布和拉伸力学性能,采用金相和透射电子显微技术分析焊缝区显微组织特征和力学性能的关系。结果表明,热轧板和冷轧-退火板搅拌摩擦焊焊接系数高达92%;焊接接头上焊核区硬度最低、拉伸断口位于焊核区;焊核区在热循环作用下发生部分再结晶导致的亚结构强化的减弱以及Al3(Sc,Zr)粒子共格强化作用的消失是搅拌摩擦焊焊核区强度下降的主要原因。 相似文献
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K. Elangovan V. Balasubramanian S. Babu 《Journal of Materials Engineering and Performance》2008,17(6):820-830
AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring
a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state
joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool
to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed,
axial force, etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop
an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy.
To obtain the desired strength, it is essential to have a complete control over the relevant process parameters to maximize
the tensile strength on which the quality of a weldment is based. Therefore, it is very important to select and control the
welding process parameter for obtaining maximum strength. To achieve this various prediction methods such as response surface
method (RSM), analysis of variance (ANOVA), Student’s t-test, coefficient of determination, etc., can be applied to define the desired output variables through developing mathematical
models to specify the relationship between the output parameters and input variables. Four factors, five levels central composite
design have been used to minimize number of experimental conditions. The developed mathematical relationship can be effectively
used to predict the tensile strength of FSW joints of AA2219 aluminum alloy at 95% confidence level. 相似文献
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A novel non-keyhole friction stir welding technique was proposed to weld the butt joint of 6061-T6 aluminum alloy with the thickness of 6 mm. A sound joint was obtained by this technique, simultaneously eliminating the flash, shoulder mark and keyhole defects. The sleeve directly affected zone (SDAZ) and the sleeve indirectly affected zone (SIAZ) were divided into the joint according to the plunging position of the hollow sleeve. The lack of root penetration defect was avoided when the plunging depth of the hollow sleeve was only 4.2 mm, because the hollow part inside the sleeve improved the material flow below the sleeve. An S-shaped line was left at the SIAZ, and the height of it had the minimum value of 1.47 mm at 20 mm/min. Whether the failure location of the joint was in SIAZ/SDAZ or the heat-affected zone (HAZ) depended on the height and bonding strength of the S-shaped line. The joint fracture location changed from the SIAZ/SDAZ at 35 mm/min to the HAZ at 20 and 30 mm/min. The maximum tensile strength of 224.3 MPa was obtained at 30 mm/min which was 73.7% of that of the base material. The fracture surface morphology exhibited the typical ductile fracture. 相似文献
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采用4种形状的搅拌针对3 mm厚的6082-T6铝合金板进行静轴肩搅拌摩擦焊焊接(SSFSW),研究了不同形状搅拌针焊接接头的宏观形貌、微观形貌及力学性能,以及搅拌针的产热。结果表明,三角形搅拌针与四边形搅拌针产热较低,动静体积比较大,接头处塑性金属流动性强,焊接过程中焊缝顶部与底部温差较小,可以形成无缺陷的SSFSW接头;XRD分析表明,焊核区无新的物相产生,三角形搅拌针焊接接头焊核区微晶尺寸最小;各接头的硬度均呈“U”形分布,最低点位于后退侧热机影响区与焊核区交界处,三角形搅拌针接头的硬度整体略高;三角形搅拌针焊接接头的抗拉强度与断后伸长率最高,分别为202.9 MPa和3.8%;拉伸断口形貌分析表明,所有接头均为韧性断裂。 相似文献