Using torque sensitivity analysis in accessing Friction Stir Welding/Processing conditions

The use of Friction Stir Processing (FSP) techniques for the joining and/or transforming of metallic materials is being object of intensive research since the earliest development of the Friction Stir Welding (FSW) technology in 1991. Despite of this, an accurate understanding of the main welding/processing mechanisms and its relation with the process parameters is still missing. Current paper intends to provide some further insight on this subject by discussing the relations between processing parameters, classified as independent variables, and the corresponding welding results, classified as dependent variables, using torque sensitivity analysis. The relation between base materials properties, plate thickness, welding conditions and torque evolution were also explored, which constitutes a novelty relative to the previous studies on this subject.     

钛合金搅拌摩擦焊接最新研究进展

钛合金具有密度低、比强度高,耐蚀性好,加工性能优异等优点,主要应用于航空航天、交通运输和石油化工等领域。当钛合金作为结构材料应用在不同领域时,传统的熔融焊接方法会产生较大残余应力,组织粗化,变形大,裂纹和孔隙等缺陷;而采用搅拌摩擦焊接技术可以避免传统熔融焊接方法产生的缺陷,从而大幅度提高钛合金焊接接头质量。目前,钛合金的搅拌摩擦焊接技术已成为国内外研究热点。主要介绍搅拌摩擦焊接的原理、工艺特点,国内外关于钛合金FSW焊接接头的宏观形貌、微观组织(晶粒大小、织构)和力学性能等方面的最新研究进展,最后展望了钛合金FSW未来的研究方向。     

镁合金AZ31B搅拌摩擦焊研究

研究了镁合金AZ31B搅拌摩擦焊接工艺参数(搅拌头转速n、焊接速度v、焊接压力P)及搅拌头材料和形状对焊接头的影响。结果表明,采用高速钢制圆台带凹面形的搅拌头效果较好;其合适的工艺参数范围是n=950～1500r/min,v=37.5～60mm/min,P=3kN;最优工艺参数为:n=1500r/min,v=47.5mm/min,P=3kN。     

Numerical optimisation of laser assisted friction stir welding of structural steel

ABSTRACT

Significant progress has been made on the implementation of friction stir welding (FSW) in the industry for aluminium alloys. However, steel FSW and other high-temperature alloys is still the subject of considerable research, mainly because of the short life and high cost of the FSW tool. Different auxiliary energies have been considered as a means of optimising the FSW process and reducing the forces on the tool during the plunge and traverse stages, but numerical studies on steel are particularly limited. Building on the state-of-art, laser-assisted steel FSW has been numerically developed and analysed as a viable process amendment. Laser-assisted FSW increased the traverse speed up to 1500?mm?min^?1, significantly higher than conventional steel FSW. The application of laser assistance with a distance of 20?mm from the rotating tool reduced the reaction force on the tool probe tip up to 55% when compared to standard FSW.     

搅拌摩擦焊焊缝超声TOFD检测与缺陷评估方法

针对特种焊接构件中缺陷取向与检测面垂直的情况,采用超声衍射时差技术（TOFD）,对搅拌摩擦焊（FSW）焊缝中的缺陷进行识别和可视化检测,开展搅拌摩擦焊焊缝超声TOFD检测与缺陷评估方法研究。建立了FSW缺陷判别方法,实现了焊接工艺参数的优化,确保了焊缝质量,对FSW的推广和应用具有重要的意义和实际生产价值。     

强制冷却搅拌摩擦焊接工艺

搅拌摩擦焊接在工业生产中应用的主要问题之一,是焊接硬化状态材料时接头强度系数较低.简要分析了焊接热对接头强度的影响,提出了在搅拌摩擦焊接过程中进行强制冷却的工艺方法.对比了强制冷却对紫铜搅拌摩擦焊接头表面状况、硬度分布和接头性能的影响,建立了强制冷却搅拌摩擦焊接过程中焊接区温度的近似表达式.结果表明,在紫铜搅拌焊接过程中进行强制冷却,可以降低焊接过程中焊缝及热力影响区变形金属的温度,减小接头软化的程度和范围,提高搅拌摩擦焊接接头的性能.采用转速1 500 r/min、移动速度0.3 mm/s的强制冷却的工艺方法,得到的紫铜搅拌摩擦焊接头抗拉强度达269 MPa.     

铝合金船舶的摩擦搅拌焊接工艺

摩擦搅拌焊(FSW)是在低于工件材料熔点情况下操作的固相焊接,是在旋转情况下通过一种耐磨工具将板材或型材材料连接的工艺,可用于铝、镁、铜等的焊接,焊接质量优良.通常情况下,摩擦搅拌焊的焊缝强度超过热影响区.介绍了摩擦搅拌焊在造船和船舶制造业上的应用,以及船舶工业的研究需求.     

搅拌摩擦焊技术在军用飞机航空修理中的应用

介绍了军用飞机航空修理中现有焊接技术的缺陷以及搅拌摩擦焊(FSW)的发展现状.提出了FSW技术在军用飞机航空修理中的应用设想,并进行了可行性分析,初步探索了针对军用飞机裂纹、破孔和缺口等损伤形式的FSW修理应用前景.最后指出FSW技术在军用飞机航空修理中大规模推广应用需解决的几个问题.     

Progress in friction stir welding of Ni alloys

In recent years, interest has been increasing in application of Nickel alloys in the oil industry. For subsea engineering, the possibility to weld high-strength materials in an effective manner is essential. Friction Stir Welding (FSW) is alternative to join several materials retaining their properties or even improving them. This fact is relevant for Corrosion-Resistant Alloys (CRA) used in deep-water exploitation of hydrocarbons. Publications up to now have focused on FSW of Inconel® series as alloy 600, 625, and 718. To provide a solid basis for development, this review discusses the crucial points for FSW. The tool materials are described, as well as the joint microstructure and properties achieved. Furthermore, the basics of the corrosion resistance and the early corrosion studies of FSW joints are presented. It is concluded that FSW is a promising process for Ni alloys, but depends on upcoming research regarding tool technology and corrosion investigations.     

Critical review on friction stir welding of aluminium to copper

The status quo of aluminium-to-copper joining by friction stir welding (FSW) drastically changed in recent years, as a result of the increased interest of the scientific community on this subject. Actually, since 2006 a large increase in the number of research groups addressing Al–Cu FSW has been witnessed all over the world, together with a significant increase in the amount of published studies. A chronological perspective on the evolution in Al–Cu FSW research is provided in this work, highlighting the pioneer and original contribution of several researchers to the current knowledge on the subject. Detailed and comprehensive investigations on the material flow mechanisms, the phenomena governing the formation and distribution of intermetallic phases during Al–Cu FSW, their relations with the welding parameters and their impact on the morphological, structural and mechanical properties of the welds are thoroughly discussed. The main findings reported in the literature are summarised in thematic tables.     

高镁铝合金搅拌摩擦交叉焊接头微观组织与力学性能

为满足大型铝合金船舶壁板的制造需求,对新一代高镁铝合金进行了搅拌摩擦交叉焊接试验. 结果表明,交叉焊接头成形良好,搅拌区晶粒尺寸最小,热力影响区晶粒形态没有明显方向性,与单道搅拌摩擦焊相比,交叉焊接头搅拌区晶粒组织更细. 显微硬度测试结果表明,交叉焊接头显微硬度变化范围较小,前进侧接头软化明显;拉伸试验测试结果表明,交叉焊接头抗拉强度为340 MPa,为母材强度的87%,对比搅拌摩擦焊接头抗拉强度358 MPa略微降低,在热影响区断裂,断裂方式为45°韧性断裂;疲劳裂纹萌生于焊缝底部,在最大应力150 MPa下循环超2 × 106次未断裂,疲劳性能良好,瞬断区断裂方式为韧性断裂.     

酸性盐雾下2024铝合金搅拌摩擦焊接头的腐蚀行为

在详细分析2024铝合金搅拌摩擦焊焊缝表面微结构的基础上,采用酸性连续盐雾试验研究焊缝表面的腐蚀行为。组织分析表明,焊缝表层因受搅拌头轴肩水平挤压作用而呈现弧形条纹特征,并导致晶粒和第二相粒子得到显著细化;合金中的第二相粒子主要为棒状的Al₂CuMg（S相）和颗粒状的CuAl₂（θ相）。盐雾试验表明,搅拌摩擦焊焊缝区耐蚀性因包铝层遭到破坏而呈现下降趋势,腐蚀程度因焊缝表面残留的纯铝而呈现不均匀性。腐蚀首先从局部点蚀开始,最终演变为剥落腐蚀。     

A Review of FSW Research on Dissimilar Metal and Alloy Systems

This review summarizes friction-stir welding (FSW) research over a period of a decade and a half, involving 18 different same materials FSW reference systems, and the FSW of 25 different, dissimilar materials systems. These are summarized in tables. The FSW of dissimilar materials systems is distinguished from same materials systems FSW by the formation of complex, intercalated vortex, and related flow patterns. These intercalated, lamellar-like patterns represent solid-state flow by dynamic recrystallization (DRX) which facilitates unrecrystallized, block flow in the DRX regime. A detailed characterization of representative systems involving optical and transmission electron microscopy is also presented. Residual microindentation hardness or other hardness measured across the weld face provides comparative performance signatures for the same material FSW systems in contrast to the dissimilar FSW systems. Hardness fluctuations or complex spikes occurring in the dissimilar systems are skewed from the weld centerline and are shifted when the tool rotation direction changes or the advancing side is reversed.     

镁合金搅拌摩擦焊接技术的研究进展

搅拌摩擦焊是一种节能、节材、清洁、高效的新型金属连接技术，特别适于轻金属的连接。铝合金搅拌摩擦焊技术已经在很多领域实现了工业应用，而镁合金搅拌摩擦焊的研究才刚刚开始。对搅拌摩擦焊的技术特点作了简要的介绍，并对镁合金搅拌摩擦焊接工艺以及材料的组织与性能方面的研究进行了综述，并对以后的研究方向作了展望。     

我国搅拌摩擦焊技术的研究现状与热点分析

从搅拌摩擦焊材料、工艺、焊接机理、有限元数值模拟、接头耐腐蚀性等方面分析了国内对搅拌摩擦焊研究取得的成果与现状,并预测了未来几年国内搅拌摩擦焊研究的热点和重点.分析认为:铝合金仍是未来几年搅拌摩擦焊的主要研究材料,而镁合金、铜合金、不锈钢、碳钢以及异种金属的搅拌摩擦焊将也将成为研究的热点.焊接工艺、有限元数值模拟以及接...     

中国搅拌摩擦焊技术的研究

综合评述了我国搅拌摩擦焊的研究成果和不足之处,包括接头的微观组织和力学性能、材料的流动行为、焊接热循环和温度场以及焊接设备等方面的内容。在此基础上,指出了进一步研究的方向,例如,微观组织研究应深入到沉淀相、织构和位错的尺度上,接头性能研究应从工程应用角度出发,材料流动行为和温度分布研究的重点应放在更深层次的理论研究和分析上。     

Review of research progress on aluminium–magnesium dissimilar friction stir welding

The paper critically assesses the research progress towards aluminium–magnesium dissimilar friction stir welding (FSW). First, the theoretical requirements are explored through the understanding of joining mechanism and heat generation in aluminium–magnesium FSW. Next, the observed trends in microstructural characterisation and mechanical properties are analysed. Finally, the effects of welding parameters and how it influences process variables and materials responses are discussed in detail, and several suggestions are made based on these discussions.     

Alternative friction stir welding technology for titanium–6Al–4V propellant tanks within the space industry

Friction stir welding (FSW) offers an appealing solid state joining alternative to traditional fusion welding techniques for titanium alloys because it reduces problems associated with high temperature processing. Propellant tanks are a critical component of every spacecraft and contain several weld seams and a prime candidate for this innovative technology. This paper reviews the current technological maturity of FSW relative to titanium alloys and considers the application with respect to a pressure vessel. FSW is currently in a period of significant investment by large engineering companies and international research institutions. The technology is advancing and evolving to cater for high temperature alloys. Stationary shoulder FSW and hybrid techniques show promising potential with respect to Ti–6Al–4V. The tool material and limited process window for this material are restrictive factors at present but can be overcome with future development.     

镁合金搅拌摩擦焊研究现状及进展

传统的熔焊工艺焊接镁合金存在很多问题,搅拌摩擦焊是解决这些问题的有效途径。简要介绍了搅拌摩擦焊的基本原理和主要优缺点,综述了近年来国内外镁合金搅拌摩擦焊的研究进展,分析了镁合金搅拌摩擦焊的焊缝成形、接头组织、力学性能等,展望了镁合金搅拌摩擦焊的应用前景。     

Friction stir welding of aluminum to copper—An overview

Components made by joining different materials are required in various engineering applications. Fabrication of such components is a challenging task due to the vast difference in mechanical, thermal and electrical properties of the materials being used. Friction stir welding (FSW) is capable of joining dissimilar materials such as aluminum (Al) and copper (Cu) and therefore researchers have used this novel process for dissimilar joining. Consequently, several works pertaining to dissimilar joining, specifically Al-Cu, are available in the literature but they are scattered in different sources, which makes the task of gathering information about dissimilar FSW of Al-Cu cumbersome. This work has been written with an aim to provide all pertinent information related to dissimilar FSW of Al-Cu at one place to ease the problems of researchers. It comprehensively covers and summarizes the topics such as the effect of tool design and geometry, FSW process parameters, FSW strategies on mechanical properties, microstructure and formation of defects during dissimilar FSW of Al-Cu. In addition, it also presents and discusses several variants of dissimilar FSW of Al-Cu. Finally, this work not only puts forth major findings of the previous researchers but also suggests future recommendations for dissimilar FSW of Al-Cu.