Haris Ali Khan The Harold and Inge Marcus Department of Analyses of Friction Stir Riveting Industrial and Manufacturing Engineering, Penn State University, State College, PA 16801 Processes: A Review e-mail: [email protected] This study presents detailed analyses of variant joining processes under the category of Jingjing Li1 friction stir riveting (FSR) that are applied to assemble similar or dissimilar materials by Mem. ASME integrating the advantages of both friction stir process and mechanical fastening. It cov- The Harold and Inge Marcus Department of ers the operating principle of FSR methods along with the insights into various process Industrial and Manufacturing Engineering, parameters responsible for successful joint formation. The paper further evaluates the Penn State University, researches in friction stir-based riveting processes, which unearth the enhanced metal- Downloaded from http://asmedigitalcollection.asme.org/manufacturingscience/article-pdf/139/9/090801/6405942/manu_139_09_090801.pdf by guest on 25 September 2021 State College, PA 16801 lurgical and mechanical properties, for instance microstructure refinement, local e-mail: [email protected] mechanical properties and improved strength, corrosion, and fatigue resistance. Advan- tages and limitations of the FSR processes are then presented. The study is concluded by Chenhui Shao summarizing the key analyses and proposing the potential areas for future research. Department of Mechanical [DOI: 10.1115/1.4036909] Science and Engineering, University of Illinois at Urbana-Champaign, Keywords: friction stir, joining, dissimilar materials, process physics, mechanical Urbana, IL 61801 properties e-mail: [email protected] 1 Introduction partly pierces the lower sheets before undergoing the effect of the lower upsetting die, which radially dislocates the hollow rivet end Today’s manufacturing industry is inclined toward evolving outward [13]. Simultaneously, the work material is displaced to new technologies to meet rapidly changing needs [1]. Among fill any created voids. The entire process generates a mechanical those, weight savings and increasing fuel efficiency emerged as interference and interlocking. However, two-sided access is man- particular demands [2] in industries like aviation and automotive. datory for this process. Details of the process are illustrated in Lightweight materials such as Mg and Al alloys, carbon steels, Fig. 1(c) [14]. In recent years, mechanical riveting methods such and polymer composites are widely used in combination for as SPR and BR are widely used in automotive industry for joining achieving the desired results [3,4]. These manufacturing advance- of dissimilar materials [15,16]. ments call for new efficient joining technologies. Dissimilar mate- The welding institute is the pioneer in inventing friction stir rial joining poses more challenges than similar materials because welding (FSW) in 1991 [17]. Friction stir spot welding (FSSW) is of difference in their mechanical, chemical, and thermal proper- a derivative of this process [18]. In FSSW, the material pieces are ties. Nonetheless, dissimilar materials are difficult to be joined in fastened by a welding tool through both sides. The welding tool is multimaterial structures using conventional fusion-based welding brought into contact with the parts at a desirable rotational speed methods. Mechanical fasteners, e.g., bolting and riveting, can be (RS). Consequently, frictional heat is generated. The tool is fur- used independently as well as in combination with adhesives ther driven into the work material under pressure until it partially [5,6]. Current mechanical fastening substitutes for joining materi- penetrates through both the work materials. The frictional heat als are solid riveting, blind riveting (BR), and self-piercing rivet- generated during the process results in softening and subsequently ing (SPR), to name a few [7]. joining of work materials [19–23]. The process is explained in Solid riveting is a conventional fastening technique [8] where a Fig. 1(d) [24]. In automotive industry, FSW of aluminum and solid rivet is placed inside a predrilled hole. The rivet shank steel is utilized for manufacturing of vehicle components for deforms under an axial compressive load to fill the hole/cavity instance, the trunk hinge on the Mazda MX-5 [25] and the hybrid and forms the rivet clinch (Fig. 1(a) [9]). BR [10] is one type of steel/aluminum sub frame presented by Honda on the 2013 solid riveting; however, in this process, more intricate rivets are Accord [26]. used. A blind rivet has two components, mandrel and shank. The From the previously mentioned discussion, it can be inferred mandrel is a long rod with an increased diameter at one end; and that there are several mechanical riveting or friction stir mecha- the shank comprises a hollow tube with a flat cap on the end. The nisms for dissimilar materials. In addition, technologies including internal diameter is capable of housing the mandrel. The three adhesive bonding, laser welding, or other solid-state methods steps of BR are predrilling, placing, and pulling [11]. The first (e.g., ultrasonic welding) are being applied in joining dissimilar step, predrilling, is to drill a hole on the work materials with a materials. However, there is a continuous rise in the expansion of diameter larger than the rivet’s body diameter. The second step, substitute joining technologies to minimize the limitations of con- placing, as the name suggests, involves a blind rivet seating into the temporary processes, such as joint performance, production time, predrilled hole. The third step, pulling, is to drag the mandrel of the and cost. This results in evolution of new techniques, which can blind rivet until the mandrel breaks off. Figure 1(b) [12] gives a meet the stringent manufacturing requirements, particularly in schematic representation of the process. In a self-piercing riveting, robustness and ease of implementation. Therefore, this paper aims a hollow rivet is driven into the specimen materials that are incor- at analyzing and comprehending an emerging joining technique, porated in a shaped die. Initially, the rivet is driven into the upper FSR processes, which integrates the advantages of both friction surface of the work materials because of the pressure applied stirring and mechanical riveting. FSR are novel joining processes, (through the press punch). At this stage, the rivet penetrates which eradicate the necessity of predrilling for rivet insertion, and through the upper sheets of materials. At the same time, it also thus surmount the difficulties in hole alignment. The processes are fast, only taking a few seconds to form a joint, and ready with implementation of robot systems. There are different variants in 1Corresponding author. Manuscript received February 16, 2017; final manuscript received May 19, 2017; use for FSR processes, which are friction riveting, friction self- published online July 18, 2017. Assoc. Editor: Wayne Cai. piercing riveting (F-SPR), friction bit joining (FBJ), two-sided Journal of Manufacturing Science and Engineering SEPTEMBER 2017, Vol. 139 / 090801-1 Copyright VC 2017 by ASME Downloaded from http://asmedigitalcollection.asme.org/manufacturingscience/article-pdf/139/9/090801/6405942/manu_139_09_090801.pdf by guest on 25 September 2021 Fig. 1 Schematic of different joining processes: (a) solid riveting [9], (b) blind riveting [12], (c) self-piercing riveting [14], and (d) friction stir welding [24] friction stir riveting by extrusion, and friction stir blind riveting (FSBR). This paper covers a comprehensive review of the differ- ent FSR processes starting from the description of different proc- esses and fundamentals of the process design, followed by the analytical modeling studies, the underlying process parameters, different bond formations, and characterization of affected zones; presents research on mechanical behavior of FSR joints, behavior under corrosive environment; and in the end, concludes with syn- opsis and future outlook. 2 Process Physics and Experimental Setup This section will cover important aspects related to process physics involved in the accomplishment of FSR processes. Each process is discussed individually, and processes sharing common- ality are grouped together. 2.1 Friction Riveting. Many researchers joined various dis- similar materials by exploiting the advantages of friction stirring and mechanical fastening. Researchers at Helmholtz-Zentrum, Geesthacht, Germany [27] invented friction riveting process (called FricRiveting) to join hybrid thermoplastic-metal structures Fig. 2 Schematic illustration of FricRiveted process [28]: (a) through spot connections. One or more thermoplastic components fixturing of joining materials, (b) axial movement of the rotating are joined with metal by inserting a round profiled (or plain) rivet into polymeric partner(s), (c) increase of axial force and metallic rivet in them. In this process, the surface of the plastic forging of the rivet, and (d) anchor formation of deformed rivet component is pressed by a rotating metallic rivet (Fig. 2(a))at tip and consolidation of joint 090801-2 / Vol. 139, SEPTEMBER 2017 Transactions of the ASME high rotational speeds. The applied axial force and high rotational moving rotating rivet interacts with the material; (2) hot riveting speed generate frictional heat, thereby creating a plasticized/ stage in which the rotating rivet penetrates into the upper work- molten film around the rivet tip (Fig. 2(b)).