| ZHANG Hao,WANG Youqiang,DUAN Jizhou.Effect of Traverse Speed on the Properties of Pin-less Friction Stirred Modified Layers of Aluminum Alloys[J],54(8):96-106 |
| Effect of Traverse Speed on the Properties of Pin-less Friction Stirred Modified Layers of Aluminum Alloys |
| Received:June 26, 2024 Revised:December 02, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.08.008 |
| KeyWord:FSP 2024 aluminum alloy surface modification mechanical properties corrosion resistance traverse speed |
| Author | Institution |
| ZHANG Hao |
School of Mechanical and Automotive Engineering, Qingdao University of Technology, Shandong Qingdao , China;Key Laboratory of Marine Environmental Corrosion and Bio-fouling, Institute of Oceanology, Chinese Academy of Sciences, Shandong Qingdao , China;Open Studio for Marine Corrosion and Protection, Qingdao National Laboratory for Marine Science and Technology, Shandong Qingdao , China |
| WANG Youqiang |
School of Mechanical and Automotive Engineering, Qingdao University of Technology, Shandong Qingdao , China |
| DUAN Jizhou |
School of Mechanical and Automotive Engineering, Qingdao University of Technology, Shandong Qingdao , China;Key Laboratory of Marine Environmental Corrosion and Bio-fouling, Institute of Oceanology, Chinese Academy of Sciences, Shandong Qingdao , China;Open Studio for Marine Corrosion and Protection, Qingdao National Laboratory for Marine Science and Technology, Shandong Qingdao , China;Center for Ocean Mega-Science, Chinese Academy of Sciences, Shandong Qingdao , China |
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| Abstract: |
| FSP is a green, environmentally friendly, and efficient surface modification technology. It can reduce the generation of cracks, porosity, and other defects on the alloy surface and improve its surface properties. To increase the depth of the stirring area, traditional FSP generally uses a stirring head with a stirring pin. Nevertheless, inserting the stirring pin into the alloy matrix may destroy the microstructure, which could subsequently lead to a reduction in the overall performance and an accelerated deterioration to the service life of alloy components. To circumvent the issues mentioned, the work aims to utilize a pin-less stirring head to facilitate FSP modification treatment on the surface of the 2024 aluminum alloy (BM). Furthermore, the effect of the traverse speed on the properties of the modified layer of the alloy is investigated. The 2D stirring friction welding equipment model HT-JC6×8/2 was employed to implement a pin-less stirring friction modification treatment on the surface of the aluminum alloy. The process parameters were as follows, including the spindle speed of 1 000 r/min, and the traverse speed of 40 mm/min, 60 mm/min, 80 mm/min, 100 mm/min, and 120 mm/min. Tensile and corrosion specimens (from the FG) were extracted from the surface of the modified layer by EDM wire cutting. Anode film of the modified layer specimens was conducted in a 5% HBF4 solution at room temperature to facilitate observation of the metallographic microstructure of the modified layer. The DC voltage was set to 18 V for 150 s. The microstructure, polarized corrosion morphology, tensile fracture morphology, and tensile mechanical properties of the modified layer were analyzed by OM, SEM, TEM, and a YYF/slow strain rate stress corrosion tester. Additionally, a three-electrode system was employed for electrochemical testing of the modified layer to study the corrosion behavior of the modified layer in 3.5% NaCl solution under different traverse speed conditions. An analysis of the tensile and electrochemical corrosion properties of the modified layer specimens showed that the performance of the modified layer peaked at a traverse speed of 100 mm/min. The cross section of the modified layer was bowl-shaped, and the surface grains were significantly refined, with no defects such as porosity and cracks. The modified layer could be divided into three distinct zones according to the size and shape of the grains, including FG, TG, and CG. The thickness of the FG was between 1 024.3 μm and 1 247.3 μm. When the traverse speed was 100 mm/min, compared with the BM, the σ0.2 and σb were enhanced by 19.2% and 24.5%, respectively, and the δ could be up to 20.3%. The fracture form of the modified layer was dominated by ductile fracture. At this juncture, the modified layer had the best corrosion resistance. In comparison to the BM, the Ecorr of the modified layer was enhanced from −1.283 V to −0.539 V, while the Jcorr was diminished from 6.680×10−5 A/cm2 to 2.448×10−6 A/cm2. Concurrently, in the Nyquist curve, the capacitive arc radius was the largest. In the polarized corrosion morphology, there were almost no large corrosion spots, which corroborated the exceptional corrosion resistance of the material. The pin-less FSP modification uses the shoulder of the stirring head to contact the surface of the alloy. Under the combined effect of frictional heat and stress, the alloy undergoes plasticization and intense plastic deformation, which refines the microstructure of the alloy surface (grains, S-phase). The refined S-phase is uniformly dispersed in the modified layer through the rotation of the stirring head, thereby achieving the effect of dispersion strengthening. The synergistic effect of fine grain and dispersion strengthening allows the modified layer to obtain excellent comprehensive performance. |
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