6061-T6铝合金的静止轴肩搅拌摩擦焊工艺及组织性能

采用自主研制的静止轴肩搅拌摩擦焊工具系统成功获得了6061-T6铝合金的对接接头. 对该接头的焊缝成形、显微组织、硬度分布以及拉伸性能分别进行了试验研究. 结果表明,SSFSW工艺所得6061-T6铝合金接头具有非常美观的焊缝成形,与常规的FSW工艺相比,几乎没有出现焊缝减薄的现象;焊缝组织分区也有明显的不同,TMAZ非常窄,只有几百微米;接头的硬度呈"W"形分布;在转速1 000 r/min,焊速为200 mm/min时,接头的抗拉强度和断后伸长率达到最大,分别为母材的71.5%和44.6%;拉伸试样均断裂在热影响区,它是接头发生断裂的最薄弱区域.     

Fabrication of Al/Al2Cu in situ nanocomposite via friction stir processing

The aim of present work is fabrication of Al/Al₂Cu in situ nanocomposite by friction stir processing (FSP) as well as investigation of FPS parameters such as rotational speed, travel speed, number of FSP passes, and pin profile on the microstructure, chemical reaction, and microhardness of Al based nanocomposite. The Al₂Cu particles were formed rapidly due to mechanically activated effect of FSP as well as high heat generation due to Al-Cu exothermic reaction. The microstructure of the nanocomposites consisted of a finer grained aluminium matrix (～15 µm), unreacted Cu nanoparticles (～40 nm), and reinforcement nanoparticles of Al₂Cu. Irregular morphology of Al₂Cu is attributed to the local melting during FSP. Pin diameter has a higher effect on the microstructure and hardness values. The hardness measurements exhibited enhancement by 57% compared with the base metal.     

焊后热处理对2219-T6铝合金搅拌摩擦焊接头力学性能的影响

采用搅拌摩擦焊方法对2219-T6铝合金进行焊接,对焊接接头的宏观形貌、显微组织、拉伸强度、显微硬度进行了分析。结果表明,焊核区组织为细小的晶粒,热机影响区组织为弯曲变形的晶粒,热影响区组织出现了明显粗化。接头室温拉伸强度可以达到母材的75%左右,接头强度低于母材的原因主要归结为金属的塑性损伤、缺陷的产生和热影响区的软化。通过固溶及时效方法并兼顾再结晶过程的热处理工艺可以回复接头塑性、消除软化,达到改善接头性能的目的。     

2024-T4铝合金搅拌摩擦焊搅拌区位错及组织性能

采用金相、显微硬度及透射分析方法对2024铝合金搅拌摩擦焊接头搅拌微区的组织性能和位错分布特征进行试验分析,基于位错分析深入了解各微区位错形成与接头组织结构与硬度变化之间的关系。研究表明,WNZ位错主要分布在晶粒内部,大部分是以位错缠结的形式存在,并伴随有大量的沉淀强化析出相Cu_2Mg;而在TMAZ区,大量的位错是以位错塞积的形式存在于晶界或晶粒内部;HAZ区域的位错多以位错塞积的形式存在于晶界附近,并伴随一些典型的Al Cu_3析出相。WNZ和TMAZ区中并未随晶粒细化而造成位错数量和类型的减少,这与FSW特殊的动态回复和动态再结晶过程有关,此外位错分布特征与接头微区硬度分布特征基本吻合。     

Influence of multi-pass friction stir processing on microstructure and mechanical properties of 7B04-O Al alloy

Three-pass friction stir processing (FSP) with different moving distances of the stirring tool between the two successive passes, 50% diameter of the pin (traditional way) and 50% diameter of the shoulder (novel way), was conducted on 7B04-O Al alloy. The result shows that an improvement in the mechanical properties of the processed zone is accomplished due to grain and second phase particles refinement. The hardness of the multi-pass FSP (M-FSP) sample is about HV 40 higher than that of the base metal. And the tensile strength of the M-FSP specimens is also significantly increased to about 1.4 times that of the base metal. Besides, the weak region of the processed zone is mainly dependent on the moving distance, where it is the previous pass stir zone in the traditional way and the transitional zone in the novel way. Increasing the rotational speed narrows the weak region in the novel way, while it does not in the traditional way.     

Microstructure and wear performance of Al5083/CeO2/SiC mono and hybrid surface composites fabricated by friction stir processing

Friction stir processing (FSP) was utilized to produce surface composites by incorporating nano-sized cerium oxide (CeO₂) and silicon carbide (SiC) particles individually and in combined form into the Al5083 alloy matrix. The study signified the role of these reinforcements on microstructure and wear behavior of the resultant surface composite layers. The wear characteristics of the resultant mono and hybrid surface composite layers were investigated using a pin-on-disc wear tester at room temperature. The microstructural observations of FSPed regions and the worn out surfaces were performed by optical and scanning electron microscopy. Considerable grain refinement and uniform distribution of reinforcement particles were achieved inside the nugget zone. All the composite samples showed higher hardness and wear resistance compared to the base metal. Among the composite samples, the hybrid composite (Al5083/CeO₂/SiC) revealed the highest wear resistance and the lowest friction coefficient, whereas the Al5083/SiC composite exhibited the highest hardness, i.e., 1.5 times as hard as that of the Al5083 base metal. The enhancement in wear behavior of the hybrid composites was attributed to the solid lubrication effect provided by CeO₂ particles. The predominant wear mechanism was identified as severe adhesive in non-composite samples, which changed to abrasive wear and delamination in the presence of reinforcing particles.     

铝合金静止轴肩搅拌摩擦焊组织非均质性对接头力学性能的影响

对6061-T6铝合金静止轴肩搅拌摩擦焊(stationary shoulder friction stir welded, SSFSW)接头组织非均质性与力学性能的相互影响进行了定量分析. 结果表明,SSFSW焊接接头存在明显的组织非均质性,表现在晶粒尺寸及形状、沉淀相种类及分布形态不同,其中沉淀相析出不同是影响力学性能差异的主要因素. 由于组织非均质性导致紧邻焊核区的热影响区软化严重,其硬度和抗拉强度在接头区域最低,分别为母材的60%和72%,为接头最薄弱部分. 由于沉淀强化和晶粒细化效应,焊核区的强度与塑性最好,而抗拉强度和断后伸长率分别达到母材的88%和215%. 随着与焊核区距离的增加,热影响区抗拉强度和屈服强度逐渐增加,断后伸长率不断降低.     

6mm厚6061-T6铝合金双轴肩搅拌摩擦焊工艺方法研究

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%。     

6061-T6铝合金双轴肩搅拌摩擦焊接头组织与力学性能

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。     

2219-T87铝合金搅拌摩擦焊接头组织与力学性能

采用搅拌摩擦焊方法对8mm厚2219-T87铝合金进行了焊接.对接头的宏观形貌、微观组织、显微硬度及断口形貌进行了分析.结果表明,焊核区为细小的等轴晶粒,晶粒尺寸远小于母材;热机影响区发生了弯曲变形;热影响区组织出现了明显粗化.前进边热机影响区和焊核区形成明显分界线,后退边相对模糊.搅拌摩擦焊对接头各区域沉淀相分布形态有重要影响.接头室温拉伸强度可以达到母材的70%以上.沿焊缝横截面的显微硬度的分布显示,硬度最低点位于后退侧热影响区区域,断裂位置位于后退侧热影响区处,接头的断裂形式为韧性断裂.     

铝合金超声搅拌复合焊接

铝合金的搅拌摩擦焊（FSW）通常在焊接区形成上高下低”浅漏斗状”的温度场,使焊缝厚度方向的组织性能差异较大．为了得到更好的焊接效果,文中提出超声搅拌复合焊思想,将超声波通过搅拌头导入焊缝纵深处,以改善焊缝组织性能．试验采用2．5mm厚的2219铝合金分别用上述两种方法进行焊接,并对焊缝的微观组织和力学性能进行了分析比较...     

7050-T7451铝合金搅拌摩擦焊接头组织和性能与疲劳断裂

文中主要对7050-T7451铝合金搅拌摩擦焊焊接接头组织性能和疲劳断裂进行研究,对焊件进行金相组织、硬度、疲劳试验,并根据试验结果进行分析。试验结果表明,焊核区和热力影响区组织有明显的分界,整个接头表面和截面的不同区域的组织有明显的不同,焊核区经历高温热循环,并且受到强烈的搅拌作用,发生了显著的动态再结晶,组织均匀细小,没有明显的方向性。热力影响区组织在搅拌摩擦焊接过程中主要受到热循环作用的影响,同时一定程度上受到了机械外力的作用,产生了较小的塑性变形,但储能不够,最终未出现动态再结晶。热影响受到热循环的作用,组织比母材要粗大,但没有发生明显塑性变形,仍具有母材纤维组织的特点。硬度试验的结果表明,母材区和焊核区的硬度比较大,而热影响区的硬度偏低,热力影响区的硬度在它们之间。通过对疲劳试验分析,应力水平为200 MPa时,试样在前进侧热影响区发生断裂,断口的表面较为粗糙。应力水平为250 MPa时,试样在焊核区发生断裂,断口表面较为平整。应力水平为300 MPa时,试样在母材处发生断裂,断口表面十分平整。创新点： 通过搅拌摩擦焊工艺形成的7050-T7451铝合金焊接接头,成形良好,技术优势突出,适用于航天航空等多个重要领域。     

AA6061-T6与AZ31合金异种搅拌摩擦焊接头的微观组织

研究了AA6061-T6和AZ31合金异种搅拌摩擦焊接头的微观组织。在异种搅拌摩擦焊接AA6061-T6与AZ31合金时,采用偏置条件,即将搅拌针插入时偏向AZ31合金,从而得到异种对接接头。通过预备实验来优化搅拌针的前进速度、旋转速度。运用电子背散射衍射技术观察搅拌区的纹理,并得到粒径分布和错位角分布,在搅拌区存在相对精细的晶粒结构。在AA6061-T6搅拌区出现随机或弱面取向,而在AZ31搅拌区出现旋转底面取向。再结晶颗粒的平均尺寸只有2．5～4．5μm。与基础合金相比,在AA6061-T6搅拌区的大角度晶界的分数增大,而在AZ31搅拌区的小角度晶界的分数降低。     

二硼化钛对Al2024−TiB2非原位复合材料摩擦磨损性能的影响

用搅拌铸造法制备不同质量分数二硼化钛(TiB2)颗粒增强的铝基复合材料,并研究其摩擦磨损性能.采用销?盘式摩擦试验机对Al2024?TiB2复合材料进行干滑动磨损试验.为了研究摩擦学参数对复合材料的影响,对载荷、滑动距离和滑动速度等参数进行调整.显微组织表征结果表明,TiB2颗粒分散均匀并与基体有良好的结合.实验结果表...     

LF2铝合金搅拌摩擦焊接接头的组织与性能

对10 mm厚LF2铝合金搅拌摩擦焊接进行了研究.结果表明:焊接厚板时,为防止出现隧道型缺陷,须在较低的焊速和转速下进行.当焊速为9 mm/min,转速为950 r/mln,焊接输入能量为6 230 W时,接头强度值最高,其值与母材强度值相等.接头处由平均尺寸约为15 μm的均匀细小的晶粒组成;热影响区平均晶粒尺寸较大,其最大值约为28 μm;热机械影响区内组织细长,局部区域最大长度可达到85 μm.焊核区平均硬度与母材相当,中心最高硬度可达HV95,近缝区硬度低于母材硬度.     

2A14-T6铝合金双轴肩搅拌摩擦焊特征及接头组织性能分析

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.     

铝合金搅拌摩擦焊异种焊接头的显微组织和力学性能

对8mm厚6082/5083铝合金进行了搅拌摩擦焊焊接,焊后通过金相分析、拉伸试验和断口形貌观察等方法研究了搅拌摩擦焊异种焊接头的显微组织和力学性能.研究结果表明:在旋转速度800 r/min、焊接速度120 mm/min工艺条件下,接头表面成形良好,内部无明显缺陷.焊核区是由细小的等轴晶组织构成;前进边和回转边的界面形态差异较为明显,前进边的组织形貌呈花纹状,由两种铝合金组织交互融合而成,但回转边组织形貌则呈曲线状,明显将两种组织分开.断口形貌分析显示,接头断裂模式为脆性断裂.     

Rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys

The tensile rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys were examined. The experiments show that the rupture locations of the joints are different for the two aluminum alloys, which are influenced by the welding parameters. When the joints are free of welding defects, the AA2017-T351 joints are ruptured in the weld nugget adjacent to the thermo-mechanically affected zone on the advancing side and the rupture surfaces appear as oval contours of the weld nugget, while the AA6061-T6 joints are ruptured in the heat affected zone on the retreating side and the rupture surfaces are inclined at a certain degree to the bottom surfaces of the joints. When welding defects are present in the joints, the AA2017-T351 joints are ruptured in the weld center, while the AA6061-T6 joints are ruptured on the retreating side near the weld center. The rupture locations of the joints are dependent on the internal structures of the joints and can be explained through them.     

Mechanical properties of underwater friction stir welded 2219 aluminum alloy

Underwater friction stir welding of 2219 aluminum alloy was carried out in order to further improve the joint performances by varying welding temperature history. The results indicated that the tensile strength of the joint can be improved from 324 MPa by external water cooling action in normal to 341 MPa. However, the plasticity of the joint is deteriorated. The underwater joint tends to fracture at the interface between the weld nugget zone and the thermal mechanically affected zone on the advancing side during tensile test, which is significantly different from the normal joint.     

5052与6061异种铝合金搅拌摩擦焊接头的组织和力学性能

采用搅拌摩擦焊(FSW)方法对6 mm厚的5052和6061异种铝合金进行了焊接,采用光学显微镜(OM)、扫描电镜(SEM)分析母材和焊接接头的显微组织和断口形貌,利用XRD分析了搅拌区域的物相组成,并测试了室温拉伸性能和显微硬度。结果表明,5052合金置于前进侧时更有利于材料在焊核区域的相互混合,焊接接头的最低硬度在5052合金一侧热影响区(HAZ),并在这个区域发生了断裂,断裂特征为韧性断裂。焊接接头的最大抗拉强度为225 MPa,伸长率为5.77%。