Friction Stir Welding and Processing XI: Lightweight Materials & High Entropy Alloys
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Yuri Hovanski, Brigham Young University; Piyush Upadhyay, Pacific Northwest National Laboratory; Yutaka Sato, Tohoku University; Nilesh Kumar, University of Alabama, Tuscaloosa; Anton Naumov, Peter The Great St. Petersburg Polytechnic University
Monday 8:30 AM
March 15, 2021
Room: RM 39
Location: TMS2021 Virtual
Session Chair: Nilesh Kumar, University of Alabama
8:30 AM
Case Study: Implementation of FSW in the Colombian Rail Transport Sector: Elizabeth Hoyos- Pulgarín1; Jeroen De Backer2; Santiago Escobar1; Jonathan Martin2; Mauricio Palacio3; 1Universidad EIA; 2TWI; 3Metro de Medellín
Medellín is the second-largest city in Colombia and the only one to have a metro system: Metro de Medellín (MdM), a mass-transport system that on average transports 811 thousand people daily. An exercise was carried out to identify components requiring spares and, a tie, part of the doors opening and closing mechanism, was selected. This component was originally manufactured from a bespoke extruded U-shaped AA6063-T83 profile with arc-welded brackets and milled-features.FSW provides a solution for joining aluminium alloys compared to arc welding, but high investment costs for equipment remains an obstacle for its implementation in small workshops. To take advantage of FSW for small batches, a manufacturing-strategy was proposed based on the capabilities and limitations in the local metalworking sector, enabling implementation on conventional milling machines. Representative demonstrators have then been successfully manufactured for further testing. Finally, a cost comparison between the existing manufacturing route and FSW is presented.
8:50 AM
Three Sheet Al Alloy Assembly for Automotive Application: Piyush Upadhyay1; Hrishikesh Das1; Daniel Graff1; 1Pacific Northwest National Laboratory
We present process development and characterization of 3 sheet friction stir lap welds (FSLW) in three aluminum alloys ( 7xxx, 5xxx, and 6xxx). Welding speed of 0.3-2.9m/min was used with pin length >5mm with the aim to reduce upturn hooking on the retreating side and avoid wormhole defect on the advancing side root. Joints were also made in KSII configuration to enable T peel and U peel testing. Several stitch patterns of welds were used to understand its effects on T peel and U peel performance. Hat section welds for 3 point bending and axial crush testing were also made and tested with promising results. Along the way, we have identified several challenges that require further investigations including flash management near the trim edge, weld quality with limited clamping, tool failures at speeds greater than 0.5m/min, and propensity of incipient melting for 7xxx stack-up.
9:10 AM
Bobbin Friction Stir Processing of AZ31B Mg Alloy Plates: Eisha Khalid1; Vasanth Shunmugasamy1; Bilal Mansoor; 1Texas A&M University at Qatar
Bobbin Friction Stir Processing (BFSP) is a technique used to engineer the microstructure of materials through severe plastic deformation and Dynamic Recrystallization. In the current work, we utilized BFSP to engineer the properties of 3 mm thick AZ31B magnesium alloy plates. The controlled process parameters were rotational speed and translational speed. The translational speed was held constant at 10 mm/min while rotational speed was varied from 1400 rpm to 2000 rpm. A defect-free coupon was obtained in which grain refinement of 30% of BM and texture strengthening was observed. Vickers microhardness of the coupons showed certain peak values in the stir zone. Tensile testing results were in accordance to the observed microstructural details, where highest tensile strength of 196 MPa and yield strength of 106 MPa was observed at room temperature. Results suggest BFSP is a potential tool to engineer microstructure and mechanical properties of magnesium alloys.
9:30 AM
Characterization and Analysis of the Effective Wear Mechanisms on FSW Tools: Michael Hasieber1; Michael Grätzel1; Jean Pierre Bergmann1; 1Technische Universität Ilmenau
This study systematically analyses effective wear mechanisms at the shoulder and probe, separately for plunging and welding. The investigations were carried out with a robotic welding setup in which AA-6060 T66 sheets with a thickness of 8 mm were joined by varying weld seam lengths. To compare and differentiate the wear mechanisms between plunging and welding, repeated plunging cycles are initially investigated without tool travel. Subsequent experiments consider the welding as well whereby adhesion, abrasion, surface fatigue and corrosive wear were characterised for various weld seam lengths. During welding of the AA-6060 T66 sheets the tool material 1.2344 (X40CrMoV5-1) exhibited abrasive wear occurred due to self-damaging of the FSW tool. Furthermore it was found that tool wear was influenced by variations in the degree of hardness and tempering process. The wear analysis showed that no significant wear occurred during the plunging stage.
9:50 AM
Friction Stir Lap Welding between Al and FeCoCrNiMn High Entropy Alloy: Haining Yao1; Ke Chen1; Muyang Jiang1; Min Wang1; Xueming Hua1; Lanting Zhang1; Aidang Shan1; 1Shanghai Jiao Tong University
Friction stir lap welding between single-phase FeCoCrNiMn high entropy alloy (HEA) and commercial pure aluminum (AA1060) was studied. Sound joints were produced at a traverse speed of 50mm/min and a rotation speed of 1500RPM. The tensile shear strength reached ~240N/mm. The joint fractured at Al base material, showing a high interfacial bonding. The interfacial microstructure was carefully characterized. A transition layer of ~2μm thick was observed at the interface, which is mainly of Al-rich FCC crystal structure rather than intermetallic compound (IMC). Elemental distribution is not homogeneous, with Cr and Mn locally depleted where also shows a change in crystal structure. To the aluminum side nearby the transition layer, there shows a particle-embedded composite layer. Different from brittle IMC formation in welding of dissimilar metals, the transition layer here shares the same FCC crystal structure with both base materials, which is possibly the key for the high interfacial bonding.
10:10 AM
Modified Friction Stir Welding of Al-Mg-Cu-Zn Aluminum Alloy: Ahmad Alali Alkhalaf1; Anna Tesleva1; Pavel Polyakov1; Matthias Moschinger2; Sebastian Fritsche2; Iuliia Morozova3; Anton Naumov1; Fedor Isupov1; Gonçalo Pina Cipriano2; Sergio T. Amancio-Filho2; 1Peter the Great St.Petersburg Polytechnic University (SPbPU); 2Graz University of Technology; 3Brandenburg University of Technology Cottbus-Senftenberg
Friction Stir Welding (FSW) is adopted to join the Al-Mg-Cu-Zn (7xxx) aluminum alloys in order to improve strength and ductility of the joints. The paper presents an investigation to the effect of the modified FSW methods such as Impulse FSW (IFSW) and High-Speed FSW (HS-FSW) on the microstructure and mechanical properties of the AA7075 TXX aluminum alloy. It was demonstrated that the tensile properties and hardness of the IFSW joints could be improved compared to the traditional FSW joints by variation of the impulse parameters (force and frequency). This enhancement is caused by microstructural changing. The brittle fracture of the HS-FSW joints are explained by the presence of defects in the weld zone. It indicates that heat input was insufficient or intermixing in the stir zone was inadequate. In order to avoid defects, the stirring action is planned be improved with a threaded tool or further adoption of the parameters.
10:30 AM
Heterogeneous Structure-induced Strength-ductility Synergy by Partial Recrystallization during Friction Stir Welding of a High-entropy Alloy: Po-Ting Lin1; Hung-Chi Liu1; Po-Ying Hsieh1; Cheng-Yu Wei1; Che-Wei Tsai1; Yutaka Sato2; Shih-Che Chen3; Hung-Wei Yen3; Nian-Hu Lu3; Chih-Hsuan Chen3; 1National Tsing Hua University; 2Tohoku University; 3National Taiwan University
To apply high-entropy alloys (HEAs) for extensive advanced structural uses, their welding properties should be well understood. In this study, Al0.3CoCrCu0.3FeNi HEA was butt welded by friction stir welding (FSW). The partially recrystallized fine-grained microstructure in the stir zone gave rise to a high tensile yield strength of 920 MPa with an elongation of 37%. By microstructural observation, the excellent mechanical properties of the stir zone material were attributed to the partially recrystallized heterogeneous structure, with which the synergetic strengthening improved the strength of the HEA with considerably less trade-off in its ductility. This unique phenomenon was unprecedented in any other FSWed conventional alloys and was credited to the low stacking-fault energy and the high grain growth activation energy of the HEA. This work suggests that FSW can not only produce good HEA welds but serve as a special processing technique to enhance mechanical properties of HEAs.