航空用铝合金2024摩擦焊接工艺参数优化及显微组织（英文）

开展航空用铝合金2024的连续驱动摩擦焊工艺优化试验,并表征焊接接头的显微组织演变。结果表明,摩擦压力是影响焊接接头抗拉强度的最显著因素,而采用适中的摩擦压力匹配较短的摩擦时间和较高的顶锻压力更易获取较高抗拉强度的接头。采用田口分析优化后的焊接工艺参数,焊后接头抗拉强度能够达到原始母材的92%。通过解析求解得到优化焊接工艺参数下焊接过程中摩擦界面的峰值温度处于779-794K,与试验测量结果吻合良好。由于高温和塑性变形的影响,摩擦界面的晶粒发生动态再结晶后尺寸明显细化。热影响区的晶粒细化有限,大部分原始晶粒受塑性流动影响发生变形。在摩擦阶段由于界面区域原始强化相发生固溶,且在随后冷却中二次析出不完全,最终导致摩擦界面的显微硬度降低。     

Al5052铝合金/C27200铜合金异种材料搅拌摩擦点焊的工艺窗口（英文）

采用搅拌摩擦点焊对Al5052铝合金和C27200铜合金进行异种材料焊接,并研究材料有效焊接的工艺窗口如旋转速率-停留时间图和旋转速率-插入深度图。采用中心复合设计模型,建立了预测拉伸剪切失效载荷和界面硬度随旋转速率、插入深度和停留时间变化的经验模型。采用95%置信度的ANOVA分析对模型进行验证。采用响应曲面法对所得模型进行优化,以得到最大拉伸强度和最小界面硬度。在最佳条件下,焊接接头的最大拉伸剪切失效载荷为3850 N,最小界面硬度为HV81。验证实验表明所得模型的预测误差小于2%。所得工艺窗口可为设计工程师选择搅拌摩擦点焊工艺参数提供参考,以获得良好的接头。     

基于LSSVM和AFSA的摩擦焊接工艺参数优化

为了准确和快速确定最佳摩擦焊接工艺参数,提出了一种最小二乘支持向量机与鱼群算法相结合的摩擦焊接工艺参数优化方法。以摩擦时间、摩擦压力和顶锻压力3个主要摩擦焊接工艺参数为优化对象,焊接接头抗拉强度为优化目标,通过最小二乘支持向量机拟合优化对象与优化目标之间的复杂函数关系。首先进行焊接试验,以试验数据为样本对模型进行训练,然后用鱼群算法对模型进行优化,获得最佳摩擦焊接工艺参数。结果表明,该方法具有建模容易、求解快捷等优点,优化得到的工艺参数与正交回归优化的工艺参数相比,使焊接接头的抗拉强度提高了2.1%。     

基于数学模型的热处理铝合金水下搅拌摩擦焊接参数优化

在热处理铝合金搅拌摩擦焊接中,焊接热循环会使接头局部软化,降低接头性能。水下搅拌焊接技术已被证明可以提高接头强度。为了获得最佳水下搅拌摩擦焊接工艺条件,建立了2219-T6铝合金水下搅拌摩擦焊接数学模型,最大限度地来优化焊接参数。结果表明,水下搅拌摩擦焊接接头可以达到360 MPa的抗拉强度,远高于正常焊接条件下的抗拉强度。     

应用响应曲面法优化摩擦焊接Ti-6Al-4V和SS304L工艺参数（英文）

提出了摩擦焊接过程中近优化设置工艺参数。基于不同的输入参数,如摩擦压力、摩擦时间、顶锻压力和顶锻时间及输出参数,如拉伸强度、硬度和材料损耗,成功获得摩擦焊接工艺。采用夹层技术,通过摩擦焊接工艺,连接Ti-6Al-4V和SS304L。采用响应曲面法和Box-Behnken设计确定实验次数并证实优化工艺参数,以得到更好的接头强度。结果很令人满意。在摩擦压力为12 N/mm~2、顶锻压力为40 N/mm~2、摩擦时间为1.2 s、定锻时间为7 s的条件下,得到接头强度为523 MPa。     

超硬铝合金搅拌摩擦焊全局动态鲁棒控制技术

针对7075超硬铝在传统熔焊过程中易出现热裂纹、气孔等焊接接头软化问题,建立基于搅拌摩擦焊接工艺参数变化与焊接接头强度间的动态鲁棒控制关系. 根据全局运动与焊接强度参数间的非线性关系,建立搅拌针运动动态鲁棒控制模型,对焊接接头的断后伸长率、抗拉强度、硬度等物理参数进行计算. 建立未来时刻焊接过程工艺参数的鲁棒动态进化优化模型,实现工艺参数实时优化控制. 根据模型进行的一系列焊接接头强度试验结果,该模型的预测结果可以满足工程需要,具有工程实用价值.     

搅拌摩擦焊工艺参数对铸态A356铝合金抗拉强度的影响(英文)

A356是一种高强度铝硅铸造态合金,广泛用于食品、化工、船舶、电器和汽车行业。熔焊这种铸造合金时存在许多问题,如孔隙、微裂隙、热裂等。然而,用搅拌摩擦焊(FSW)来焊接这种铸造态合金可以避免上述缺陷发生。研究了搅拌摩擦焊工艺参数对铸造态A356铝合金抗拉强度的影响;对旋转速度、焊接速度和轴向力等工艺参数进行优化;从宏观和微观组织分析角度对焊接区的质量进行分析;对焊接接头的抗拉强度进行了测定,并对抗拉强度与焊缝区硬度和显微组织的相关性进行了研究。在旋转速度1000r/min、焊接速度75mm/min和轴向力5kN的条件下得到的焊接接头具有最高的抗拉强度。     

异种镁铝合金多缝搅拌摩擦焊包覆接头的制备和性能评估（英文）

建立了异种镁铝合金包覆接头连续多缝搅拌摩擦包覆工艺参数(旋转速度、焊接速度和重叠比)和质量表征(结合抗拉强度,剪切强度和腐蚀)的经验关系,研究了工艺参数对包覆性能的影响。采用多尺度优化过程得到了理想的加工条件,在该条件下制备得到的复合板具有较高的界面强度和较低的腐蚀速率。结果表明,薄的富铝连续层和不规则富镁区由金属间化合物Al_3Mg_2和Al_(12)Mg_(17)组成,机械联锁的性质对接头界面强度有很大的影响。另一方面,在搅拌摩擦过程中镁混合到铝板的量对包覆接头的耐蚀性影响很大。弯曲测试表明,包覆接头具有优良的延展性。     

搅拌摩擦焊接工艺参数对AA6061-B4C焊接接头抗拉强度的影响（英文）

搅拌摩擦焊(FSW)是一种固态连接技术,可用来连接高强度铝合金及多种陶瓷颗粒增强金属基复合材料(MMCs)。搅拌摩擦焊获得的陶瓷增强金属基复合材料焊缝优良,在增强体与基体间没有发生有害反应。对搅拌摩擦焊接工艺参数对AA6061-B4C焊接接头抗拉强度的影响进行研究。采用4因素5水平的中心复合设计来控制实验的次数。构建一数学模型来分析搅拌摩擦焊工艺参数对接头抗拉强度的影响。结果表明,在旋转速度1000r/min、焊接速度1.3mm/s、轴向力10kN、增强相含量12%的条件下,搅拌摩擦焊得到的焊接接头的抗拉强度最大。根据构建的模型采用广义简约梯度算法进行优化以得到最大的抗拉强度。金相分析表明,在焊接接头中出现了多种区域,如焊合区、热力影响区和热影响区。在焊合区观察到大量的被细化的铝基体晶粒以及粒径明显减小的B4C颗粒。在热力影响区出现塑性变形、热影响和被拉长的铝晶粒。     

2219-T87铝合金拉锻式摩擦塞补焊接头组织及性能

对6 mm厚的2219-T87铝合金板进行了拉锻式摩擦塞补焊试验,对焊接接头的微观组织、显微硬度、抗拉强度及拉伸断口进行了观察与测试. 结果表明,采用优化的摩擦塞补焊工艺可实现2219-T87铝合金母材和2219-T87铝合金塞棒的冶金连接. 拉锻式摩擦塞补焊过程中,塞棒承受拉应力,应优化接头设计和焊接工艺参数从而防止塞棒被拉断. 未焊合是接头的主要缺陷,易出现在接头的近上表面处. 焊缝区发生明显软化,最低硬度出现在靠近连接界面的塞棒热力影响区,最低值为84.4 HV. 接头的抗拉强度可达326.4 MPa,断后伸长率可达4.45%,抗拉强度和断后伸长率分别为母材的71.7%和44.5%,拉伸断口呈韧窝形貌.     

Development of processing windows for friction stir spot welding of aluminium Al5052 /copper C27200 dissimilar materials

Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy (Al5052) with copper alloy (C27200) and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed–plunge depth diagrams for effective joining of these materials were developed. Using a central composite design model, empirical relations were developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three process parameters such as tool rotational speed, plunge depth and dwell time. The adequacy of the developed model was verified using ANOVA analysis at 95% confidence level. Response surface methodology was used to optimize the developed model to maximize tensile strength and minimize interface hardness. A high tensile shear failure load value of 3850 N and low interface hardness value of HV 81 was observed for joints made under optimum conditions, and validation experiments confirmed the high predictability of the developed model with error less than 2%. The operating windows developed shall act as reference maps for future design engineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.     

Establishing empirical relationships to predict grain size and tensile strength of friction stir welded AA 6061-T6 aluminium alloy joints

AA 6061-T6 aluminium alloy(Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high specific strength and good corrosion resistance.Compared with the fusion welding processes that are routinely used for joining structural aluminium alloys,friction stir welding(FSW) process is an emerging solid state joining process in which the material welded does not melt and recast.Joint strength is influenced by the grain size and tensile strength of the weld nugget region.Hence,an attempt was made to develop empirical relationships to predict grain size and tensile strength of friction stir welded AA 6061-T6 aluminium alloy joints.The empirical relationships are developed by response surface methodology(RSM) incorporating FSW tool and process parameters.A linear regression relationship was also established between grain size and tensile strength of the weld nugget of FSW joints.     

Effect of nickel coating on the shear strength of FSW lap joint between Ni–Cu alloy and steel

Cu–Ni alloy and low-carbon steel were joined by friction stir lap welding (FSLW) with the help of a nickel coating. The appropriate welding parameters were investigated and the lap joints were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and shear strength testing. The shear strength of joints with a nickel coating was about 2.9 times as high as that of the joints without Ni coating. According to the EDS analysis of the fractured surfaces under the shear strength test, the micro-voids occurred in the Cu–Ni/steel interface without Ni coating, thus reducing the shear strength. These micro-voids were reduced in size using a nickel coating due to the self-diffusion in the Ni/Ni interface at high interface temperature and high contact pressure. The strong bonding mechanism using a nickel coating could be explained by the iron and copper atoms diffusing into the coating through the interface at high interface temperature and holding time.     

2219铝合金与不锈钢惯性摩擦焊接接头组织与力学性能

异种金属的连接可实现节能、经济及减重的目标,成为航空航天、造船、铁路运输等领域的研究热点之一;而铝合金与不锈钢物理化学性能差异明显,成为异种金属中最难实现的连接接头之一。采用惯性摩擦焊接技术进行2219铝合金与不锈钢回转体的连接,分析不同焊接工艺参数下铝钢惯性摩擦焊接接头的显微组织与力学性能。结果表明,惯性摩擦焊接使铝钢接头铝合金一侧形成了细晶区和拉长晶区;EDS结果显示焊接界面处发生了Fe、Al等元素扩散。硬度测试结果表明,在连接界面处-0.6~+0.15 mm范围内硬度值发生了明显的阶跃变化,该区域为受焊接热及变形作用的主要区域,硬度值高于母材。合理焊接工艺下获得的2219铝合金与不锈钢接头拉伸强度为235~300 MPa。铝钢惯性摩擦焊接断口以脆性断裂为主。     

Fabrication and performance evaluation of dissimilar magnesium–aluminium alloy multi-seam friction stir clad joints

This investigation is aimed to establish empirical relationships between continuous multi-seam friction stir cladding process parameters (i.e., rotational speed, welding speed and shoulder overlap ratio) and the quality characteristics (bond tensile strength, shear strength and corrosion) of dissimilar magnesium–aluminium alloy clad joints. The influence of considered process parameters on the clad properties was reported. Furthermore, multi-criterion optimization procedure was used to obtain ideal processing conditions, which can yield higher interface strength and lower corrosion rate of fabricated composite plate. Results indicate that, the aluminium-rich thin continuous layer, Mg-rich irregular shaped regions consists of Al₃Mg₂ and Al₁₂Mg₁₇ intermetallic compounds and nature of mechanical interlocking has great influence on the joint interface strength. On the other hand, the corrosion resistance of the clad joints is greatly affected by the amount of magnesium mixed with top aluminium sheet during friction stirring. Also, bend testing shows that, the cladded joints exhibit excellent ductility.     

Microstructure and Properties of Friction Stir Welded Joints of Al-Mg-Sc Alloy Plates

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。     

7050-T7451铝合金的搅拌摩擦焊接试验分析

在不同焊接参数下进行了7050-T7451铝合金的搅拌摩擦焊接试验,对接头显微组织进行了光学和TEM分析,并测试了接头的抗拉强度和硬度分布.焊接工艺参数通过影响接头微观组织和焊接缺陷来影响接头的力学性能,在转速800r/min和焊速200mm/min的情况下,接头的抗拉强度最高达到母材强度的88%.焊接热输入较高时,接头的拉伸断裂出现在热影响区,而热输入较低时,焊缝底部出现未焊合,接头从此处首先发生开裂.结果表明,焊核区发生了动态再结晶和沉淀相溶解;热影响区发生了沉淀相粗化,晶间出现无沉淀带.     

ZL114A铸铝搅拌摩擦焊接头性能

研究了采用不同焊接参数时ZL114A铸铝搅拌摩擦焊接头的金相组织、硬度分布及力学性能。结果表明，ZL114A铸铝的搅拌摩擦焊焊接性良好。焊核区的微观组织是无方向性的、细小的等轴晶粒。细化的硅粒子均匀布满整个焊核区。与粗大的树枝状母材相比，焊核晶粒细小、均匀而致密，没有观察到气孔等缺陷。焊缝区硬度分布较母材稳定，变化范围小。随着焊速增加，硅粒子所占体积比逐渐下降。热一机械影响区晶粒被拉长。接头的力学性能与焊接参数的匹配有关系。采用高焊速及转速与焊速比在3左右，获得的接头抗拉强度可达到母材的91％。焊后经T6热处理，可与同炉热处理母材等强。     

工艺参数对Ti/Zn/Al异种金属搅拌摩擦焊接头力学性能的影响

以3 mm厚2A14铝合金和TC4钛合金为对接材料,0.05 mm厚Zn薄片为中间层材料进行搅拌摩擦焊对接。研究了不同焊接参数对钛/铝异种金属搅拌摩擦焊对接接头宏观形貌、微观组织、力学性能的影响。结果表明:当焊接速度为75 mm/min,旋转速度为375~950 r/min,偏移量2.5 mm时,均可获得表面成形良好的焊接接头。但随着旋转速度的增加,焊缝表面粗糙度先减小后增大,而对接接头抗拉强度逐渐降低;当旋转速度为600 r/min,焊接速度从60mm/min增大到95 mm/min时,焊缝的飞边逐渐减少。当旋转速度为375 r/min,焊接速度为75 mm/min,偏移量2.5 mm时,抗拉强度达到最大值237.3 MPa,达铝合金母材抗拉强度的56.7%。