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针对6 mm厚6061-T6铝合金板材,设计制造了不同结构形式和尺寸规格的双轴肩搅拌摩擦焊工具,并对搅拌摩擦焊工具的结构形式和尺寸规格对焊接过程及焊接接头质量的影响进行了系统的分析研究:设计制造了两体式和三体式双轴肩搅拌摩擦焊工具,并对两种结构形式进行分析;设计制造了环状轴肩和凹面轴肩,通过焊接工艺试验得知凹面轴肩焊缝成形性优于环状轴肩;设计制造了正-反螺纹搅拌针、正螺纹搅拌针、整圆柱搅拌针和圆柱铣扁搅拌针;圆柱铣扁搅拌针焊缝焊接质量优于其他三种结构形式的搅拌针。采用凹面轴肩和圆柱铣扁搅拌针组装成的搅拌头,对6 mm厚6061-T6铝合金板材进行焊接,在主轴转速为800 r/min、焊接速度为150 mm/min工艺参数下,焊接接头得到最大抗拉强度值为220MPa,达到母材抗拉强度(315 MPa)的70%。 相似文献
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针对5.4 mm厚度2219铝合金,开展了浮动式双轴肩搅拌摩擦焊接试验及工程化应用研究,采用低转速、高焊速的工艺参数,获得了成形美观、性能优良的焊接接头。焊缝超声相控阵检测及X射线检测均满足航天行业相关标准一级焊缝的要求,接头平均抗拉强度达到了母材性能的70%以上,断后伸长率达到6.5%以上。焊接接头均为45°剪切韧性断裂,塑性良好。整个焊缝截面呈上、下宽,中间窄的细腰形,焊缝两侧热力影响区为抛物线轮廓,未出现焊核凸出现象。在前期大量试验验证的基础上,率先实现了该技术在运载火箭贮箱焊接生产上的工程化应用,成功完成了某型号燃料贮箱筒段纵缝的焊接,焊缝顺利通过了常温液压及液氮低温试验考核。 相似文献
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针对5.4 mm厚度2219铝合金,开展了浮动式双轴肩搅拌摩擦焊接试验及工程化应用研究,采用低转速、高焊速的工艺参数,获得了成形美观、性能优良的焊接接头。焊缝超声相控阵检测及X射线检测均满足航天行业相关标准一级焊缝的要求,接头平均抗拉强度达到了母材性能的70%以上,断后伸长率达到6.5%以上。焊接接头均为45°剪切韧性断裂,塑性良好。整个焊缝截面呈上、下宽,中间窄的细腰形,焊缝两侧热力影响区为抛物线轮廓,未出现焊核凸出现象。在前期大量试验验证的基础上,率先实现了该技术在运载火箭贮箱焊接生产上的工程化应用,成功完成了某型号燃料贮箱筒段纵缝的焊接,焊缝顺利通过了常温液压及液氮低温试验考核。 相似文献
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为了研究双轴肩搅拌摩擦焊缝内部焊接残余应力的大小及分布情况,本研究采用短波X射线衍射进行焊接件内部残余应力的无损检测分析;采用光学显微分析、显微硬度和电子背散射衍射(Electron Back-scattering Patterns,EBSD)对焊缝的前进侧和后退侧的母材、热影响区、热机械影响区和焊核区的组织结构演变进行了分析。金相观察结果显示双轴肩搅拌摩擦焊的接头组织在厚度方向上近似于对称分布,呈“腰鼓形”,焊核区与热机影响区的界面为近似双曲线,前进侧热机影响区的分界线更明显。EBSD扫描结果显示热影响区、热机械影响区均存在较强的形变组织;焊核区在剪切变形和焊接循环热的双重影响下发生了动态再结晶,主要为弱取向组织,小角度晶界含量较大。短波X射线衍射结果表明,双轴肩FSW焊接板内部板厚中心层,纵向方向残余应力均大于横向方向;沿着焊缝,拉应力较大区间位于距焊缝起始端150~250 mm的范围内,最大拉应力为244 MPa。 相似文献
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采用分体式双轴肩搅拌摩擦焊(Bobbin-tool friction stir welding,BT-FSW)实现了10 mm厚6082-T6铝合金板材的焊接,搅拌针表面的加工螺纹特征有助于搅拌针诱发周围材料的单一剪切变形,在增加搅拌针周围材料变形复杂程度的同时提高应变速率,从而有助于弱化材料在BT-FSW接头区域组织。结果表明,当转速为300 r/min,焊接速度为400 mm/min,且压入量为0.5 mm时,获得表面及内部宏观成形良好的BT-FSW接头,接头宏观形貌呈典型的“哑铃形”;在较高程度的塑性变形影响下,BT-FSW接头内的晶粒发生动态再结晶从而生成细小的等轴晶;由于接头不同区域的摩擦热输入分布不同,接头的硬度分布呈典型的W形分布;接头抗拉强度约为母材强度的77%,断后伸长率约为母材的69%。 相似文献
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针对6 mm厚6061-T6铝合金板材,在主轴转速800 r/min,焊接速度150 mm/min参数下实现双轴肩搅拌摩擦焊接,并对一部分试件进行焊后热处理。对焊态试件和焊后热处理试件同时进行金相试验、拉伸试验和显微硬度试验对比分析。在焊态下,接头平均抗拉强度为203 MPa,达到母材的64%,接头在焊缝区32 mm的宽度区域内显微硬度出现不同程度的下降,显微硬度分布呈"W"型;接头经焊后热处理后,焊态下溶解消失的强化相重新析出,使接头组织重新得到强化,热处理态接头平均抗拉强度为292 MPa,达到母材的92%,整个焊缝区显微硬度均得到提高,焊态下"W"型显微硬度分布规律消除。 相似文献
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成功实现了2A14-T6高强铝合金的双轴肩搅拌摩擦焊,获得了表面成形良好,无内部缺陷的优质接头. 试验发现,在焊缝的焊核内存在一个由上、下轴肩和搅拌针所驱动的材料塑性流动交汇区,该交汇区靠近焊缝下表面. 微观分析表明,焊核上部的晶粒尺寸要小于其中部和下部的晶粒尺寸. 焊缝各区的块状第二相在焊接中发生了溶解和粗化,导致接头内出现了宽度近乎轴肩直径二倍的软化区;焊缝各层硬度分布接近,没有出现常规搅拌摩擦焊中常见的接头各层异性现象. 经拉伸测试证实,双轴肩焊接接头的强度系数达到了71%,拉伸时断在了焊核内的材料流动交汇区处. 相似文献
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介绍了铝合金搅拌摩擦焊接接头腐蚀行为的最新研究进展,重点讨论了铝合金搅拌摩擦焊接接头腐蚀行为的研究方法,包括应力腐蚀法、盐雾实验法、溶液浸泡法、电化学法、凝胶可视化法等,并指出其存在的问题,分析了接头腐蚀机理及提高接头耐蚀性的方法。 相似文献
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采用原位腐蚀试验、静态失重试验、浸泡试验研究了2219铝合金搅拌摩擦焊接接头的剥落腐蚀行为与机理。结果表明:2219铝合金搅拌摩擦焊焊缝腐蚀速率比母材小,焊缝的抗腐蚀性提高;腐蚀从局部点蚀开始,起源于第二相粒子与其边缘的铝基体,第二相粒子作阴极;原位腐蚀2 h后焊核与热机影响区发生晶间腐蚀,母材发生严重的点蚀;均匀分布的第二相粒子与细小的等轴晶组织是焊核区剥落腐蚀敏感性降低的主要原因。 相似文献
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采用微型电池(Microcell)和浸泡腐蚀试验研究了2219-O铝合金搅拌摩擦焊接接头在0.5mol/L NaCl中性溶液中的微区电化学特征和腐蚀行为,通过光学轮廓仪分析了经14d浸泡后接头的均匀腐蚀深度以及点蚀形貌、深度和密度,讨论了影响腐蚀行为的机理。结果表明:接头在无外电流干扰下即发生点蚀。与母材相比,热影响区的腐蚀行为没有明显改变;热机械影响区的耐蚀性略有提高;轴肩作用区(SAZ)因θ相回溶和被打碎,提高了基体中固溶的Cu含量,降低了SAZ的腐蚀速率以及点蚀深度、体积和密度,耐蚀性提高。 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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对2024铝合金板进行不同参数下搅拌摩擦焊接, 分析了焊缝表面组织, 检查了在EXCO溶液中焊缝表面的腐蚀行为, 并讨论硬度分布与腐蚀发生的关系. 结果表明, 焊后轴肩作用区晶粒细化明显. 随转速的增加, 焊缝上表面热影响区范围加宽、轴肩作用区硬度上升、耐蚀性能提高. 在转速1500 r/min、行进速度1000 mm/min下所得焊缝金属塑性流动剧烈, 轴肩作用区硬度值已接近母材的硬度值, 在EXCO溶液中浸泡10 h后仅发生点蚀. 与母材相比, 接头硬度的软化区是腐蚀发生的区域, 但硬度值最低的位置与腐蚀最严重的区域没有严格的对应关系. 相似文献
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Omar Hatamleh Preet M. Singh Hamid Garmestani 《Journal of Materials Engineering and Performance》2009,18(4):406-413
The surface treatment techniques of laser and shot peening were used to investigate their effect on stress corrosion cracking
(SCC) in friction stir welded (FSW) 2195 aluminum alloy joints. The investigation consisted of two parts: the first part explored
the peening effects on slow strain rate testing (SSRT) in a 3.5% NaCl solution, while the second part investigated the effects
of peening on corrosion while submerged in a 3.5% NaCl solution with no external loads applied. For the SSRT, the laser-peened
samples demonstrated superior properties to the other samples, but no signs of corrosion pitting or SCC were evident on any
of the samples. For the second part of the study, the FSW plates were inspected periodically for signs of corrosion. After
60 days there were signs of corrosion pitting, but no stress corrosion cracking was noticed in any of the peened and unpeened
samples. 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