Article
Chemistry, Physical
Mohamed M. Z. Ahmed, Mohamed M. El-Sayed Seleman, Essam Ahmed, Kamel Touileb, Ibrahim Albaijan
Summary: Friction stir spot welding is an important variant of the friction stir welding process, particularly for spot welding different thickness sheets in automotive applications. In this study, thin sheets of AA6082-T6 with different thicknesses (1 mm and 2 mm) were successfully welded using FSSW at various rotation speeds. Macro- and microstructural investigations, hardness tests, and tensile shear tests were conducted to evaluate the quality and mechanical properties of the FSSW joints. The results showed that defect-free spot joints can be achieved within a wide range of rotation speeds (400-1000 rpm), and the best welding condition was found to be 600 rpm for achieving different thin sheet thicknesses spot joints with desirable properties.
Article
Automation & Control Systems
Siyu Wu, Tao Sun, Yifu Shen, Yinfei Yan, Ruiyang Ni, Wenming Liu
Summary: The study applied Swing friction stir spot welding (SFSSW) technology to join AA5083 Al alloy to AZ31B Mg alloy, showing that SFSSW technology promoted bonding area and material mixing in the spot welds compared to conventional FSSW. The IMC structure in SFSSWed joints is spherical, different from the dendritic structure seen in conventional FSSW joints. IMCs were found through XRD and microhardness measurements in SFSSWed joints, which also showed a 72.95% larger lap-shear tensile load compared to conventional FSSWed joint.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Da Zhang, Jihong Dong, Jiangtao Xiong, Nan Jiang, Jinglong Li, Wei Guo
Summary: The microstructure and corrosion behavior of 7050 aluminum alloy RFSSW joint were investigated, revealing that the continuous degree of intergranular nano-precipitates is the key factor affecting corrosion susceptibility.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Crystallography
Thierry Baudin, Sandrine Bozzi, Francois Brisset, Hiba Azzeddine
Summary: The microstructure, texture gradient and mechanical properties of upper and lower AA5182 aluminum sheets in friction stir spot welding were investigated using EBSD and Vickers microhardness. The upper sheet mainly consisted of the stir zone and thermomechanically affected zone, while the lower sheet had additional heat-affected and base metal zones. Texture changes from shear-type to recrystallization texture were observed along the different zones. Microhardness decreased gradually with increasing distance from the keyhole. The microstructure and microhardness evolution were correlated based on the Hall-Petch relationship.
Article
Materials Science, Characterization & Testing
Sare Celik, Fatmagul Tolun
Summary: In this study, the effect of double-sided friction stir welding on AA5754 Al alloy was investigated, with the best welding performance observed at a tool rotational speed, feed rate, and tool tilt angle of 450 rpm, 50 mm x min(-1), and 1 degree, respectively.
Article
Materials Science, Multidisciplinary
Alireza Karimnejad, Mehrdad Ashjari, Akbar Heidarzadeh, Tohid Saeid
Summary: The study demonstrated that using optimal parameters for friction stir welding can improve the structure of rheocast alloys. Fillings voids through severe plastic deformation, eliminating porosities in the material. Friction stir welding results in the replacement of the semi-solid structure by finer equiaxed grains.
METALS AND MATERIALS INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Nicola Contuzzi, Mariia Rashkovets, Giuseppe Casalino
Summary: This study investigates the effects of dwell time, down force, and rotational speed on microstructure, microhardness, and material flow during solid-state welding. Probeless friction stir spot welding (P-FSSW) was used to join AA2024, AA6082, and AA5754 aluminum plates of different thicknesses. The results show that down force significantly influences material flow and weld quality. High friction energy and intensive material flow promote the formation of vortexes, which enhance metals mixing and grain refinement.
SCIENCE AND TECHNOLOGY OF WELDING AND JOINING
(2023)
Article
Materials Science, Multidisciplinary
Ivan S. Zuiko, Sergey Malopheyev, Sergey Mironov, Sergey Betsofen, Rustam Kaibyshev
Summary: The macro-scale distribution of secondary precipitates in friction-stir-welded 2519 aluminium alloy was found to vary within the stir zone due to local variations in welding temperature and cooling rate. Precipitation coarsening was most pronounced at the weld root, while dissolution was enhanced at the upper weld surface. Reprecipitation phenomena were most prominent in the weld nugget.
Article
Materials Science, Multidisciplinary
Zhe Liu, Zhiyu Fan, Li Liu, Shu Miao, Zhicheng Lin, Chungui Wang, Yunqiang Zhao, Renlong Xin, Chunlin Dong
Summary: In this study, 1 mm-thick AZ31 magnesium alloy sheets were joined by refill friction stir spot welding. The metallurgical features, microstructure, texture, and mechanical response of the spot-welded joints were investigated, and the effect of welding parameters on joint performance was evaluated. The results showed that the highest lap shear strength was achieved with a rotational speed of 1500 rpm and a plunge depth of 1.4 mm. A fine-grain structure was observed in the stir zone, and the grain size decreased with lower rotational speed and plunge depth. Furthermore, strain localization was observed during tensile deformation in the spot weld, and the mechanism behind this phenomenon was discussed.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Yang Han, Xiaoqing Jiang, Tao Yuan, Shujun Chen, Wentao Gong, Xiaoxu Li, Zhanliang Yu
Summary: This study investigates the vertical material flow and microstructure evolution during friction stir lap welding of 6061-T6 aluminium alloys using the material tracing technology and a new perspective of various angles of keyhole obtained by the emergency stop technique. The study reveals that the lamellar grains transform into equiaxed subgrains as the material flows from the advancing side to the leading side, and the texture also transitions. Recrystallised grains are formed at the retreating side, and plastic deformation leads to the formation of subgrains with strong A/(A) over bar texture components in the downward material flow at the trailing side.
SCIENCE AND TECHNOLOGY OF WELDING AND JOINING
(2023)
Article
Materials Science, Multidisciplinary
Kishan Fuse, Vishvesh Badheka
Summary: In this study, self-reacting friction stir welding of 6 mm thick Al 6061-T6 using water as cooling media at different temperatures was investigated. Four cooling methods were employed, with the C-RJ cooling producing the highest tensile strength compared to conventional welding.
Article
Engineering, Manufacturing
Mingrun Yu, Hongyun Zhao, Zili Zhang, Li Zhou, Xiaoguo Song
Summary: In this study, AA6061 alloy and Q235 steel were well joined by refilled friction stir spot welding without stirring steel, with an optimized shear strength of 7.31 kN achieved. The materials experienced shear deformation in the stir zones and the extrusion in hook and thermo-mechanical affected zones, resulting in different predominant textures in the weld.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Materials Science, Multidisciplinary
M. Balamurugan, S. Gopi, Dhanesh G. Mohan
Summary: In this research, a new filler added friction stir spot welding (FAFSSW) process was adopted to weld dissimilar aluminium alloys of AA5052 with AA6061, using five different tapered tool pins to enhance the mechanical and metallurgical properties of the joints. The results showed that the FAFSSW joint exhibited higher strength and a fine grain structure compared to normal FSSW joints, with magnesium (Mg) powder serving as the filler material.
MATERIALS RESEARCH EXPRESS
(2021)
Article
Materials Science, Multidisciplinary
Xiaochong Sui, Hengjian Xia, Yuding Liu, Zhengwei Li
Summary: Multilayer thin 2024 Al alloy sheets are successfully joined by friction spot welding (FSpW). The welding mode has significant effects on the microstructure and mechanical properties of the joints, with double side FSpW showing better performance in terms of crack elimination, failure load, and strength.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Nanoscience & Nanotechnology
Iuliia Morozova, Aleksandra Krolicka, Aleksei Obrosov, Yitong Yang, Nikolay Doynov, Sabine Weiss, Vesselin Michailov
Summary: This study elucidates the microhardness variations across the friction stir welded and impulse friction stir welded AA2024-T351 joints, with a special focus on the distinguished hardness peak within the heat-affected zone of the impulse welds. The hardness variation and microstructure evolution are analyzed to reveal the influence mechanisms of different welding techniques on material hardness.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Chengcheng Zhang, Kai Feng, Hiroyuki Kokawa, Bolun Han, Zhuguo Li
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2020)
Article
Metallurgy & Metallurgical Engineering
Tianbo Zhao, Yutaka S. Sato, Hiroyuki Kokawa, Kazuhiro Ito
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2020)
Article
Materials Science, Multidisciplinary
Sergey Mironov, Yutaka S. Sato, Hiroyuki Kokawa, Satoshi Hirano, Adam L. Pilchak, Sheldon Lee Semiatin
Article
Materials Science, Multidisciplinary
Shun Tokita, Hiroyuki Kokawa, Shohei Kodama, Yutaka S. Sato, Yuji Sano, Zhuguo Li, Kai Feng, Yixiong Wu
MATERIALS TODAY COMMUNICATIONS
(2020)
Article
Materials Science, Multidisciplinary
Hiroki S. Furuya, Sakiko Yabu, Yutaka S. Sato, Hiroyuki Kokawa
Summary: The study found that adding Ni effectively increased the interfacial strength of Al/Cu joints. Regardless of the presence of Ni, the joints fractured at the thick Al2Cu layer formed at the Al/Cu interface. However, adding Ni reduced the thickness of the IMC layer and formed Al7Cu4Ni particles in the weakest Al2Cu layer, contributing to the increase in joint strength.
Article
Nanoscience & Nanotechnology
Bolun Han, Chengcheng Zhang, Kai Feng, Zhuguo Li, Xiancheng Zhang, Yao Shen, Xiaodong Wang, Hiroyuki Kokawa, Ruifeng Li, Zhiyuan Wang, Paul K. Chu
Summary: The study fabricated a near full-dense hierarchical CrCoNi medium entropy alloy (MEA) using selective laser melting (SLM), achieving superior yield strength at 77K. The high strength of the material stems from a hierarchical microstructure composed of high-density dislocations and low-angle grain boundaries (LAGB). The results suggest that SLM is a viable technique for fabricating dense hierarchical CrCoNi MEA and offer a design strategy to further improve mechanical properties.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Chengcheng Zhang, Kai Feng, Hiroyuki Kokawa, Zhuguo Li, Ke Chen
Summary: This work investigates the effects of friction stir processing (FSP) on the CoCrFeMnNi alloy fabricated via laser powder bed fusion (LPBF). The study focuses on the modification of surface microstructure and the investigation of grain structures, dislocation structures, texture, and dynamic recrystallization. The experimental results demonstrate that both continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) occur during FSP, leading to a refined grain size and a more uniform grain size distribution in the stir zone (SZ).
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Chengcheng Zhang, Kai Feng, Hiroyuki Kokawa, Zhuguo Li
Summary: The relationship between the hierarchical microstructure and mechanical properties of a CoCrFeMnNi high entropy alloy built by laser powder bed fusion (LPBF) was investigated. The study found that both the columnar grain morphology and texture play important roles in the anisotropy of mechanical properties. The volume-weighted average grain size showed high accuracy in estimating the yield strength and critical twinning stress along different directions.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Xiaotong Pang, Zhihui Xiong, Shilong Liu, Junhao Sun, R. D. K. Misra, H. Kokawa, Zhuguo Li
Summary: Significant grain refinement of beta grains in metastable beta TB2 titanium alloy was achieved through the minor addition of zirconium diboride during laser melting deposition. The addition of 0.5 wt% ZrB2 resulted in smaller beta grains and improved mechanical properties, including higher ultimate tensile strength and ductility.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Chengcheng Zhang, Kai Feng, Hiroyuki Kokawa, Zhuguo Li
Summary: The origin and evolution of cellular structures during LPBF were investigated using a CoCrFeMnNi high entropy alloy. Experimental results demonstrated that chemical cells with low dislocation density were generated simultaneously and overlapped with each other. The stability of the chemical cells contributes to the unique characteristics of cellular structures relative to conventional deformation-induced dislocation structures.
MATERIALS CHARACTERIZATION
(2023)
Article
Nanoscience & Nanotechnology
Jie Zhu, Chendong Shao, Fenggui Lu, Kai Feng, Pan Liu, ShuFen Chu, Yueqiao Feng, Hiroyuki Kokawa, Zhuguo Li
Summary: This work investigates the anisotropic ductility and deformation behavior of laser powder bed fusion (LPBF) processed Inconel 625 at elevated temperature. The rotation of grains plays a crucial role in the dynamic recrystallization-like flow stress fluctuation, while grain boundary embrittlement leads to the decrease in ductility.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Jie Zhu, Hiroyuki Kokawa, Kai Feng, Zhuguo Li
Summary: The intergranular corrosion resistance of Inconel 625 produced by laser powder bed fusion was investigated using ASTM-G28 method A. Severe corrosion near fusion boundaries was unexpectedly found. The initiation and expansion of corrosion along the fusion boundaries and the relationship between microstructure and corrosion behavior were analyzed. This unusual corrosion behavior was attributed to the Volta potential variation caused by Al2O3 nanoparticles and Mo, Nb-rich precipitates near the fusion boundaries. This finding can enhance the understanding of corrosion behavior in laser powder bed fused nickel alloys.
Article
Nanoscience & Nanotechnology
Jie Zhu, Jintao Xu, Hiroyuki Kokawa, Yakai Zhao, Kai Feng, Zhuguo Li, Upadrasta Ramamurty
Summary: This study demonstrates that periodic variation in layer thickness during laser powder bed fusion (LPBF) can alter the grain growth direction and effectively suppress the formation of columnar grains. This build strategy decreases both grain size and texture intensity, resulting in reduced anisotropy in mechanical properties. The variation in grain growth direction can be explained by the thermal gradient variation near the transition area after the alteration of layer thickness. This simple strategy provides an additional and new tool for grain structure tailoring during LPBF.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Metallurgy & Metallurgical Engineering
Yutaka S. Sato, Tomoko Miyamori, Shun Tokita, Hiroyuki Kokawa
Summary: This research examined the feasibility of using friction stir welding (FSW) to repair rusted steel structures in an underwater environment. The results showed that underwater FSW could produce high-quality welds on 0.45%C steel, with lower working temperatures and faster cooling rates compared to conventional FSW. This resulted in increased hardness and tensile strength of the welds. The rust layer had minimal impact on weldability, but fragmented rust trapped near the top surface of the weld zone at higher rotational speeds decreased the strength of the weld.
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN
(2022)
Proceedings Paper
Materials Science, Multidisciplinary
Yutaka S. Sato, Yuichiro Tanai, Dalong Yi, Tianbo Zhao, Hiroyuki Kokawa
Summary: The heat-input during Friction Stir Welding (FSW) of aluminum alloys was found to be influenced by the geometry of the welding tools, with a particularly strong dependence on probe dimensions. A linear relationship between heat-input and effective surface area of the tool was experimentally shown, suggesting a higher than expected impact of probe dimensions on heat-input. Furthermore, an empirical equation successfully estimated the heat-input during FSW based on welding parameters and tool geometry.
FRICTION STIR WELDING AND PROCESSING XI
(2021)