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Wenya Li
School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, Shaanxi, PR China

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Journal article
Published: 25 August 2021 in Journal of Materials Research and Technology
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The regulated Metal Deposition (RMD™) process is a variant of the gas metal arc welding process (GMAW), which was developed to effectively control the metal transfer in the short-circuiting mode. The process is fundamentally a modified short-circuit GMAW process wherein a uniform droplet deposition, making it easier for the welder to control the puddle and hence achieve an enhanced quality of welded joints. In the present study, the RMD technique has been established for the low alloy steel grade 2.25 Cr - 1.0 Mo particularly for depositing the root pass on a 10 mm thick joint. In addition to this, the RMD technique is attempted with metal-cored wires to enhance the deposition rates and hence productivity. The joint fill-up is further attempted with the GMAW technique using metal-cored wires and analysed. The weldments were subjected to post-weld heat treatment followed by mechanical and metallurgical characterization. Mechanical characterization such as tensile properties, impact properties, bend test as well as all weld tensile properties of the weld joint was evaluated and found to be acceptable. The ductile to brittle transition temperature (DBTT) testing was carried out by breaking series of impact specimen till negative temperatures. The DBTT temperature for the weld joint was found well below -30°C which indicated the strength and soundness of the welded joint. Optical microscopy and scanning electron microscopy was carried out for and favourable results were achieved in microanalysis. The study proposes the use of metal-cored wires for potential applications in the welding of high thickness joints for enhancing the overall productivity.

ACS Style

Subhash Das; Jay J. Vora; Vivek Patel; Wenya Li; Joel Andersson; Danil Yu. Pimenov; Khaled Giasin; Szymon Wojciechowski. Experimental Investigation on welding of 2.25 Cr- 1.0 Mo steel with Regulated Metal Deposition and GMAW technique incorporating metal-cored wires. Journal of Materials Research and Technology 2021, 1 .

AMA Style

Subhash Das, Jay J. Vora, Vivek Patel, Wenya Li, Joel Andersson, Danil Yu. Pimenov, Khaled Giasin, Szymon Wojciechowski. Experimental Investigation on welding of 2.25 Cr- 1.0 Mo steel with Regulated Metal Deposition and GMAW technique incorporating metal-cored wires. Journal of Materials Research and Technology. 2021; ():1.

Chicago/Turabian Style

Subhash Das; Jay J. Vora; Vivek Patel; Wenya Li; Joel Andersson; Danil Yu. Pimenov; Khaled Giasin; Szymon Wojciechowski. 2021. "Experimental Investigation on welding of 2.25 Cr- 1.0 Mo steel with Regulated Metal Deposition and GMAW technique incorporating metal-cored wires." Journal of Materials Research and Technology , no. : 1.

Journal article
Published: 30 July 2021 in Journal of Materials Research and Technology
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The precipitation behavior and development of grain structure have been investigated to reveal their association with the microhardness and corrosion resistance of probeless friction stir spot welded (P-FSSW) joint of an Al-Li alloy. Results identified the primary strengthening phase of T1 (Al2CuLi) to be completely dissolved in the stir zone (SZ), while equiaxed grains were formed. Grain refinement was directly associated with the combined effect of continuous dynamic recrystallization and geometrized effect of imposed strain. However, as localized grain boundary bulging indicated, limited discontinuous recrystallization also participated in the microstructure evolution. The hardness dropped noticeably in the heat affected zone (HAZ) due to the weakening of precipitation and dislocation strengthening, which resulted from partial dissolution or coarsening of T1 phase and recovery effect. Grain refinement and solution strengthening were responsible for the slight increase in hardness of the SZ. In addition, the SZ had minute increased pitting resistance due to the homogenization of intermetallic particles, precipitate dissolution and refined grains.

ACS Style

Q. Chu; S.J. Hao; W.Y. Li; X.W. Yang; Y.F. Zou; D. Wu; A. Vairis. On the association between microhardness, corrosion resistance and microstructure of probeless friction stir spot welded Al-Li joint. Journal of Materials Research and Technology 2021, 1 .

AMA Style

Q. Chu, S.J. Hao, W.Y. Li, X.W. Yang, Y.F. Zou, D. Wu, A. Vairis. On the association between microhardness, corrosion resistance and microstructure of probeless friction stir spot welded Al-Li joint. Journal of Materials Research and Technology. 2021; ():1.

Chicago/Turabian Style

Q. Chu; S.J. Hao; W.Y. Li; X.W. Yang; Y.F. Zou; D. Wu; A. Vairis. 2021. "On the association between microhardness, corrosion resistance and microstructure of probeless friction stir spot welded Al-Li joint." Journal of Materials Research and Technology , no. : 1.

Journal article
Published: 05 July 2021 in Materials Science and Engineering: A
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Titanium alloy T-joints were produced using two different friction stir welding (FSW) sequences, and the local-global deformation mechanisms until fracture were compared. Due to their differing FSW sequence characteristics, the optimal parameter ranges for the two T-joints are different. The stir zone (SZ) of the single-weld T-joint consists of lamellar α grains, while fine equiaxed α grains develop in the double-weld T-joint due to the selection of low heat input. Due to the different local microstructure zones in the joint, deformation inhomogeneity of the T-joint during tensile testing is observed. Independent of the welding sequence and for optimal process conditions, both T-joint configuration show nearly the same maximum tensile strength as the base material (BM), however at a relatively low fracture strain, below 20% of the BM. The local strain hardening rate in different zones of the T-joint was investigated. The strain hardening ability of SZ with fine grains is significantly higher than elsewhere, because the grain size contributes greatly to strain hardening behavior at low strain levels. The single-weld T-joint experienced a symmetric local strain distribution between advancing and retreating side. For the double-weld T-joint, there are significant differences between the first and the second weld area. The fracture morphologies of both T-joints are typical ductile, where the toughness of the single-weld joint is higher than that of the double-weld joint.

ACS Style

Yu Su; Wenya Li; Junjun Shen; Banglong Fu; Jorge F. dos Santos; Benjamin Klusemann; Achilles Vairis. Comparing the local-global deformation mechanism in different friction stir welding sequences of Ti-4Al-0.005B titanium alloy T-joints. Materials Science and Engineering: A 2021, 823, 141698 .

AMA Style

Yu Su, Wenya Li, Junjun Shen, Banglong Fu, Jorge F. dos Santos, Benjamin Klusemann, Achilles Vairis. Comparing the local-global deformation mechanism in different friction stir welding sequences of Ti-4Al-0.005B titanium alloy T-joints. Materials Science and Engineering: A. 2021; 823 ():141698.

Chicago/Turabian Style

Yu Su; Wenya Li; Junjun Shen; Banglong Fu; Jorge F. dos Santos; Benjamin Klusemann; Achilles Vairis. 2021. "Comparing the local-global deformation mechanism in different friction stir welding sequences of Ti-4Al-0.005B titanium alloy T-joints." Materials Science and Engineering: A 823, no. : 141698.

Review
Published: 05 July 2021 in Critical Reviews in Solid State and Materials Sciences
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ACS Style

Devang Sejani; Wenya Li; Vivek Patel. Stationary shoulder friction stir welding – low heat input joining technique: a review in comparison with conventional FSW and bobbin tool FSW. Critical Reviews in Solid State and Materials Sciences 2021, 1 -50.

AMA Style

Devang Sejani, Wenya Li, Vivek Patel. Stationary shoulder friction stir welding – low heat input joining technique: a review in comparison with conventional FSW and bobbin tool FSW. Critical Reviews in Solid State and Materials Sciences. 2021; ():1-50.

Chicago/Turabian Style

Devang Sejani; Wenya Li; Vivek Patel. 2021. "Stationary shoulder friction stir welding – low heat input joining technique: a review in comparison with conventional FSW and bobbin tool FSW." Critical Reviews in Solid State and Materials Sciences , no. : 1-50.

Research article
Published: 21 June 2021 in Materials and Manufacturing Processes
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A T-joint with two welds in the same welding direction was successfully connected for an α titanium alloy using friction stir welding (FSW). The texture and joint properties under different stress directions were analyzed. Results show that grains undergo obvious recrystallization in stir zone (SZ), and the grain of SZ in the first weld is coarser compared to the SZ in the second weld due to secondary welding heat cycle. The welding temperature exceeding or not exceeding β transus greatly affects the final microstructure of the SZ, but does not affect its texture type. The Schmid factors are higher in rolling direction than those in normal direction, so the base material and SZ are more likely to deform when stress is applied in the rolling direction, which results in a lower microhardness in this direction. In addition, the effect of anisotropy on mechanical property was weaker in SZ than in base material.

ACS Style

Yu Su; Wenya Li; Fuyang Gao; Achilles Vairis. Effect of FSW process on anisotropic of titanium alloy T-joint. Materials and Manufacturing Processes 2021, 1 -9.

AMA Style

Yu Su, Wenya Li, Fuyang Gao, Achilles Vairis. Effect of FSW process on anisotropic of titanium alloy T-joint. Materials and Manufacturing Processes. 2021; ():1-9.

Chicago/Turabian Style

Yu Su; Wenya Li; Fuyang Gao; Achilles Vairis. 2021. "Effect of FSW process on anisotropic of titanium alloy T-joint." Materials and Manufacturing Processes , no. : 1-9.

Journal article
Published: 14 May 2021 in Metals
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The knowledge of process parameters–weld integrity-aging treatments–tensile property relationship is of great concern for linear friction welded (LFWed) Ti2AlNb-based alloy and requires a systematic characterization. Thus, the Ti2AlNb-based alloy was LFWed under various process parameters and then subjected to different aging treatments. Twelve welding conditions were used to evaluate the weld integrity, showing that impurities and cracks at weld interface can be eliminated under strong welding parameters and the feed rate has the greatest influence on the weld integrity among all process parameters. Relationships among aging temperatures, microstructure evolution, and mechanical properties were investigated. After aging treatment, acicular O phase has precipitated in B2 grains both in the weld zone and thermo-mechanical affected zone (TMAZ). The size of precipitated O phase increases along with the increase of temperature, and the α2 + O mixtures have finally decomposed into the aggregated acicular O phase. The microhardness and tensile strength of the joints have been enhanced due to the precipitation hardening of O phase and refined grain strengthening after aging treatments.

ACS Style

Xi Chen; Zhao Zhang; Faqin Xie; Xiangqing Wu; Tiejun Ma; Wenya Li; Dianjun Sun. Optimizing the Integrity of Linear Friction Welded Ti2AlNb Alloys. Metals 2021, 11, 802 .

AMA Style

Xi Chen, Zhao Zhang, Faqin Xie, Xiangqing Wu, Tiejun Ma, Wenya Li, Dianjun Sun. Optimizing the Integrity of Linear Friction Welded Ti2AlNb Alloys. Metals. 2021; 11 (5):802.

Chicago/Turabian Style

Xi Chen; Zhao Zhang; Faqin Xie; Xiangqing Wu; Tiejun Ma; Wenya Li; Dianjun Sun. 2021. "Optimizing the Integrity of Linear Friction Welded Ti2AlNb Alloys." Metals 11, no. 5: 802.

Journal article
Published: 27 April 2021 in Materials Characterization
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T-joints of an α titanium alloy were successfully welded by friction stir welding, and the evolution of microstructure, texture and mechanical properties were investigated. Results show that dynamic recrystallization occurs in the stir zone, and the grain morphology depends on whether the welding temperature exceeds β transus. The microhardness of the welded joint shows a W-shaped profile, with the highest values in the stir zone and the lowest ones in the heat-affected zone. The joint tensile strength in the skin direction is significantly higher than that in the stringer direction. As the rotation speed or the welding speed increase, the tensile strength of the joint increases to a maximum, followed by a drop in both the skin and stringer directions. Similarly, the joint impact toughness increases first and then decreases with the increase of rotational speed or welding speed. The impact fracture of the typical joint with 850 rpm-50 mm/min is ductile dominated by dimples. In addition, the corrosion resistance of welded joint is improved compared to that of the base material.

ACS Style

Yu Su; Wenya Li; Xichang Liu; Fuyang Gao; Yan Yu; Achilles Vairis. Evolution of microstructure, texture and mechanical properties of special friction stir welded T-joints for an α titanium alloy. Materials Characterization 2021, 177, 111152 .

AMA Style

Yu Su, Wenya Li, Xichang Liu, Fuyang Gao, Yan Yu, Achilles Vairis. Evolution of microstructure, texture and mechanical properties of special friction stir welded T-joints for an α titanium alloy. Materials Characterization. 2021; 177 ():111152.

Chicago/Turabian Style

Yu Su; Wenya Li; Xichang Liu; Fuyang Gao; Yan Yu; Achilles Vairis. 2021. "Evolution of microstructure, texture and mechanical properties of special friction stir welded T-joints for an α titanium alloy." Materials Characterization 177, no. : 111152.

Journal article
Published: 16 April 2021 in Crystals
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Al/Mg dissimilar welds were successfully fabricated by refill friction stir spot welding using a grooved sleeve tool. Influences of sleeve penetration depth and rotational speed on the weld formation and mechanical performance were systematically evaluated in terms of welding parameter optimization, interfacial bonding mechanism, hardness distribution and welded joint strength. The results indicated that the success of joining Al alloy to Mg alloy significantly depends on tool sleeve penetration depth. The interfacial bonding mechanism compromised both metallurgical bonding and mechanical inter-locking. Intermetallic compound layers of Al3Mg2 and Al12Mg17 were formed at the Al/Mg interface. The thickness of the intermetallic compound (IMC) layer at the weld center increased from 20–30 μm to 40 μm when the rotational speed increased from 1000 to 2000 rpm. The minimum hardness was 80 HV in Al 7075 and 52 HV in ZEK 100; both were measured in the heat affected zone. The welded joint lap shear strength decreased, and the scatter increased with the increasing of rotation speed, whose maximum was 3.6 kN when the rotational speed was 1000 rpm. In addition, the failure mechanism was determined by tool rotational speed, and found to be interfacial failure under a rotational speed of 1000 rpm and nugget pullout under a rotational speed of 2000 rpm.

ACS Style

Zhikang Shen; Xinyu Liu; Dongxiao Li; Yuquan Ding; Wentao Hou; Haiyan Chen; Wenya Li; Adrian Gerlich. Interfacial Bonding and Mechanical Properties of Al/Mg Dissimilar Refill Friction Stir Spot Welds Using a Grooved Tool. Crystals 2021, 11, 429 .

AMA Style

Zhikang Shen, Xinyu Liu, Dongxiao Li, Yuquan Ding, Wentao Hou, Haiyan Chen, Wenya Li, Adrian Gerlich. Interfacial Bonding and Mechanical Properties of Al/Mg Dissimilar Refill Friction Stir Spot Welds Using a Grooved Tool. Crystals. 2021; 11 (4):429.

Chicago/Turabian Style

Zhikang Shen; Xinyu Liu; Dongxiao Li; Yuquan Ding; Wentao Hou; Haiyan Chen; Wenya Li; Adrian Gerlich. 2021. "Interfacial Bonding and Mechanical Properties of Al/Mg Dissimilar Refill Friction Stir Spot Welds Using a Grooved Tool." Crystals 11, no. 4: 429.

Journal article
Published: 15 April 2021 in Journal of Materials Research and Technology
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The effect of tool morphology on the joint forming during probeless friction stir spot welding (P-FSSW) of an Al–Li alloy was evaluated with the assistance of experiments and numerical simulation. Compared to the flat tool, the surface temperature not only increased rapidly at the inner side of the shoulder periphery, but also locally appeared high value at the groove features using the tools with annular and involute profiles. In addition, the primary texture that developed during welding was determined to be a simple shear texture component of A/A¯, followed by B/B¯ and A1∗/A2∗, with the occurrence of continuous dynamic recrystallization. Based on the texture development, the circumferential material flow remained predominant due to the shear acting of the rotation shoulder. Meanwhile, the radial inward flow also existed to a certain extent, promoted by the involute feature, which was beneficial to improve the material circulation to obtain an enlarged welding area. Nevertheless, higher rotation speed for a long time should be avoided in P-FSSW as the surface material was prone to be excessively squeezed out to form flash due to the excavation effect.

ACS Style

Q. Chu; S.J. Hao; W.Y. Li; X.W. Yang; Y.F. Zou; D. Wu. Impact of shoulder morphology on macrostructural forming and the texture development during probeless friction stir spot welding. Journal of Materials Research and Technology 2021, 12, 2042 -2054.

AMA Style

Q. Chu, S.J. Hao, W.Y. Li, X.W. Yang, Y.F. Zou, D. Wu. Impact of shoulder morphology on macrostructural forming and the texture development during probeless friction stir spot welding. Journal of Materials Research and Technology. 2021; 12 ():2042-2054.

Chicago/Turabian Style

Q. Chu; S.J. Hao; W.Y. Li; X.W. Yang; Y.F. Zou; D. Wu. 2021. "Impact of shoulder morphology on macrostructural forming and the texture development during probeless friction stir spot welding." Journal of Materials Research and Technology 12, no. : 2042-2054.

Article
Published: 12 April 2021 in International Journal of Minerals, Metallurgy and Materials
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The butt welds of 4-mm thick 5A06 aluminum alloy plates were produced by adjustable-gap bobbin-tool friction stir travel with travel speeds of 200, 300, and 400 mm/min in this study. The microstructure was studied using optical microscopy and electron backscatter diffraction (EBSD). Tensile tests and microhardness measurements were performed to identify the effect of the travel speed on the joint mechanical properties. Sound joints were obtained at 200 mm/min while voids were present at different positions of the joints as the travel speed increased. The EBSD results show that the grain size, high angle grain boundaries, and density of geometrically necessary dislocations in different regions of the joint vary depending on the recovery and recrystallization behavior. Specific attention was given to the relationship between the local microstructure and mechanical properties. Microhardness measurements show that the average hardness of the stir zone (SZ) was greater than that of the base material, which was only affected slightly by the travel speed. The tensile strength of the joint decreased with increasing travel speed and the maximal strength efficiency reached 99%.

ACS Style

Dong Wu; Wen-Ya Li; Yan-Jun Gao; Jun Yang; Quan Wen; Nektarios Vidakis; Achillefs Vairis. Impact of travel speed on the microstructure and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al-Mg joints. International Journal of Minerals, Metallurgy and Materials 2021, 28, 710 -717.

AMA Style

Dong Wu, Wen-Ya Li, Yan-Jun Gao, Jun Yang, Quan Wen, Nektarios Vidakis, Achillefs Vairis. Impact of travel speed on the microstructure and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al-Mg joints. International Journal of Minerals, Metallurgy and Materials. 2021; 28 (4):710-717.

Chicago/Turabian Style

Dong Wu; Wen-Ya Li; Yan-Jun Gao; Jun Yang; Quan Wen; Nektarios Vidakis; Achillefs Vairis. 2021. "Impact of travel speed on the microstructure and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al-Mg joints." International Journal of Minerals, Metallurgy and Materials 28, no. 4: 710-717.

Journal article
Published: 10 April 2021 in Crystals
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Ti3SiC2 ceramic and copper were successfully vacuum brazed using Ag-Cu-Ti filler and Ag-Cu-Ti filler with copper mesh, respectively. In this study, the effects of copper mesh and brazing parameters on the interface microstructure and mechanical properties of the joints were systematically studied. The results revealed that the typical interfacial microstructure of joint was Ti3SiC2 ceramic/Ti5Si3 + TiC + Ti2Cu + Ti3Cu/Ag (s, s) + Cu (s, s)/eutectic Ag-Cu + TiSiCu/Cu. A maximum shear strength of joint obtained at a brazing temperature of 870 °C and a holding time of 10 min can reached up to 66.3 ± 1.2 MPa, which was 34.7% higher than that without copper mesh. The improvement of mechanical property was attributed to the extraordinary plasticity of copper mesh, which reduced the residual stress caused by the difference in the coefficient of thermal expansion at the interface of joints. As the brazing temperature and holding time further increased, the shear strength of joints decreased due to the excessively thick reaction layer of intermetallic compounds.

ACS Style

Haiyan Chen; Xin Nai; Shuai Zhao; Decai Lu; Zhikang Shen; Wenya Li; Jian Cao. Improvement for Interfacial Microstructure and Mechanical Properties of Ti3SiC2/Cu Joint Brazed by Ag-Cu-Ti Filler with Copper Mesh. Crystals 2021, 11, 401 .

AMA Style

Haiyan Chen, Xin Nai, Shuai Zhao, Decai Lu, Zhikang Shen, Wenya Li, Jian Cao. Improvement for Interfacial Microstructure and Mechanical Properties of Ti3SiC2/Cu Joint Brazed by Ag-Cu-Ti Filler with Copper Mesh. Crystals. 2021; 11 (4):401.

Chicago/Turabian Style

Haiyan Chen; Xin Nai; Shuai Zhao; Decai Lu; Zhikang Shen; Wenya Li; Jian Cao. 2021. "Improvement for Interfacial Microstructure and Mechanical Properties of Ti3SiC2/Cu Joint Brazed by Ag-Cu-Ti Filler with Copper Mesh." Crystals 11, no. 4: 401.

Research paper
Published: 10 March 2021 in Welding in the World
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Synergetic double-sided probeless friction stir spot welding is a novel process proposed in this study, which is used to solve the contradiction between the improvement of metallurgical bonding and deterioration of hook defect. The effect of the coordinated movement of the tools on the joint formation was evaluated based on the coupled Eulerian-Lagrangian technique. By flexibly adjusting the welding parameters on both sides, the mechanical interlock caused by hook defect could be effectively regulated while significantly improving the metallurgical bonding, due to the enhancement of thermo-mechanical cycle along the thickness direction. According to the microstructure analysis, the interfacial evolution was ascribed to the combined effects of plastic deformation, material flow, atom diffusion, and recrystallization, as well as local abrasion. In addition, the microhardness profile exhibited a uniform distribution. Based on the above characteristics, the technology is expected to obtain higher strength joints, which will promote its applications in the manufacture fields.

ACS Style

Q. Chu; W. Y. Li; Y. F. Zou; X. W. Yang; S. J. Hao; X. C. Liu; W. B. Wang. Preliminary investigation of a novel process: synergetic double-sided probeless friction stir spot welding. Welding in the World 2021, 1 -9.

AMA Style

Q. Chu, W. Y. Li, Y. F. Zou, X. W. Yang, S. J. Hao, X. C. Liu, W. B. Wang. Preliminary investigation of a novel process: synergetic double-sided probeless friction stir spot welding. Welding in the World. 2021; ():1-9.

Chicago/Turabian Style

Q. Chu; W. Y. Li; Y. F. Zou; X. W. Yang; S. J. Hao; X. C. Liu; W. B. Wang. 2021. "Preliminary investigation of a novel process: synergetic double-sided probeless friction stir spot welding." Welding in the World , no. : 1-9.

Journal article
Published: 17 January 2021 in Surface and Coatings Technology
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The relatively weak interfacial bond and brittleness of cold sprayed deposits limit their industrial applications for the fabrication of complex structural components. In this study, pure copper, as a typical material for cold spray additive manufacturing (CSAM), was deposited and then post-processed with conventional heat treatment (HT) and newly developed electric pulse processing (EPP) and friction stir processing (FSP), in order to improve the microstructure and mechanical properties of the deposits. The results show that EPP, FSP, and HT can heal the weak interfaces between deposited particles, with EPP and FSP being considerably better than HT. Recrystallized fine grains and elongated grains at the interfacial regions transformed into coarser grains after EPP and HT. FSP refinement affects the grains of the whole deposit and completely rearranges the topology of the deposited particles. Mechanical tests reveal that an ultimate tensile strength of 310 MPa and elongation of 40% were reached after FSP, while the ultimate tensile strength of 209 MPa and elongation of 19% were reached with EPP. The main strengthening mechanisms of the EPP deposit are the improved bonding at the interfaces and the high angle grain boundaries and twins. For the FSP deposit, the improved interface bonding, the superfine grains along with the strain hardening effect are the main strengthening mechanisms.

ACS Style

Wenya Li; Dong Wu; Kaiwei Hu; Yaxin Xu; Xiawei Yang; Yong Zhang. A comparative study on the employment of heat treatment, electric pulse processing and friction stir processing to enhance mechanical properties of cold-spray-additive-manufactured copper. Surface and Coatings Technology 2021, 409, 126887 .

AMA Style

Wenya Li, Dong Wu, Kaiwei Hu, Yaxin Xu, Xiawei Yang, Yong Zhang. A comparative study on the employment of heat treatment, electric pulse processing and friction stir processing to enhance mechanical properties of cold-spray-additive-manufactured copper. Surface and Coatings Technology. 2021; 409 ():126887.

Chicago/Turabian Style

Wenya Li; Dong Wu; Kaiwei Hu; Yaxin Xu; Xiawei Yang; Yong Zhang. 2021. "A comparative study on the employment of heat treatment, electric pulse processing and friction stir processing to enhance mechanical properties of cold-spray-additive-manufactured copper." Surface and Coatings Technology 409, no. : 126887.

Original article
Published: 12 January 2021 in The International Journal of Advanced Manufacturing Technology
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AA2219 aluminium alloy plates of large thickness ratios were successfully produced by refill friction stir spot welding (RFSSW) method. In addition to common defects, such as holes and hook, insufficient refill and weak bonding also appeared in the joints with large thickness ratios. Besides, the stir zone of the typical RFSSWed joint exhibited refined and equiaxed grains because of the dynamic recrystallization, while the elongated grains with a large proportion of the low angle grain boundaries were the main microstructure features in the thermomechanically affected zone due to insufficient heat input and deformation. Moreover, in all cases of large thickness ratio, the micro-hardness distribution of the joints presented an M-shaped profile. The maximum tensile-shear strength reached 7.2 kN, corresponding to the rotation speed of 2000 rpm, welding time of 3.6 s and plunge depth of 2.2 mm, which displayed a close correlation with the defect morphology, such as the weak bonding length and hook height. Also, two types of fracture modes were observed in the tensile-shear specimens, plug fracture mode and mixed fracture mode.

ACS Style

Yangfan Zou; Wenya Li; Qiang Chu; Zhikang Shen; Feifan Wang; Huawei Tang; Achilles Vairis; Liyuan Liu. The impact of macro/microstructure features on the mechanical properties of refill friction stir spot–welded joints of AA2219 alloy with a large thickness ratio. The International Journal of Advanced Manufacturing Technology 2021, 112, 3093 -3103.

AMA Style

Yangfan Zou, Wenya Li, Qiang Chu, Zhikang Shen, Feifan Wang, Huawei Tang, Achilles Vairis, Liyuan Liu. The impact of macro/microstructure features on the mechanical properties of refill friction stir spot–welded joints of AA2219 alloy with a large thickness ratio. The International Journal of Advanced Manufacturing Technology. 2021; 112 (11-12):3093-3103.

Chicago/Turabian Style

Yangfan Zou; Wenya Li; Qiang Chu; Zhikang Shen; Feifan Wang; Huawei Tang; Achilles Vairis; Liyuan Liu. 2021. "The impact of macro/microstructure features on the mechanical properties of refill friction stir spot–welded joints of AA2219 alloy with a large thickness ratio." The International Journal of Advanced Manufacturing Technology 112, no. 11-12: 3093-3103.

Research paper
Published: 04 January 2021 in Welding in the World
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The effects of rotation speed and plunge depth on macro/microstructures and mechanical properties of dissimilar 2195/2219 aluminum alloy joints produced by refill friction stir spot welding (RFSSW) were investigated. The results show that some shallow annular grooves present on the joint surfaces depending on the process parameters. Besides, hook defects are in the form of downward bending due to the higher strength of 2195 aluminum alloy. The change of rotating speed has no apparent influence on hook defect, while the increase of plunge depth makes the height of the hook defect increase significantly. The higher tensile-shear strength is associated with increased rotation speed. However, as the plunge depth increases, the tensile-shear strength rises first and then decreases. The highest tensile-shear strength measured is 6480 N, for a rotation speed of 1600 rpm, and plunge depth of 2.5 mm. Besides, there are two kinds of fracture modes present: the plug fracture and the shear-plug fracture.

ACS Style

Yangfan Zou; Wenya Li; Qiang Chu; Dong Wu; Yu Su; Zhikang Shen; Feifan Wang; Huawei Tang. Formability and mechanical property of refill friction stir spot–welded joints. Welding in the World 2021, 65, 899 -907.

AMA Style

Yangfan Zou, Wenya Li, Qiang Chu, Dong Wu, Yu Su, Zhikang Shen, Feifan Wang, Huawei Tang. Formability and mechanical property of refill friction stir spot–welded joints. Welding in the World. 2021; 65 (5):899-907.

Chicago/Turabian Style

Yangfan Zou; Wenya Li; Qiang Chu; Dong Wu; Yu Su; Zhikang Shen; Feifan Wang; Huawei Tang. 2021. "Formability and mechanical property of refill friction stir spot–welded joints." Welding in the World 65, no. 5: 899-907.

Journal article
Published: 28 September 2020 in Journal of Materials Science & Technology
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Cyclic deformation behavior of friction-stir-welded dissimilar AA2024-T351 to AA7075-T65 aluminum alloy joints was evaluated via stepwise tests at different strain rates, along with transmission electron microscopy examinations to characterize the precipitates required to assess internal stresses. Electron backscatter diffraction was employed to observe the inhomogeneous microstructures of the FSWed joints. Strain localization appeared in the heat affected zone (HAZ) of AA2024 side. After cyclic deformation of 500 cycles at a total strain amplitude of 0.5 %, the strength of the dissimilar joints resumed basically to that of AA2024 base material. And the AA2024 HAZ was obviously hardened, which should be attributed to the introduced dislocations during cyclic deformation process. Cyclic hardening capacity of the joints increased with decreasing strain rate.

ACS Style

P.L. Niu; W.Y. Li; D.L. Chen. Tensile and cyclic deformation response of friction-stir-welded dissimilar aluminum alloy joints: Strain localization effect. Journal of Materials Science & Technology 2020, 73, 91 -100.

AMA Style

P.L. Niu, W.Y. Li, D.L. Chen. Tensile and cyclic deformation response of friction-stir-welded dissimilar aluminum alloy joints: Strain localization effect. Journal of Materials Science & Technology. 2020; 73 ():91-100.

Chicago/Turabian Style

P.L. Niu; W.Y. Li; D.L. Chen. 2020. "Tensile and cyclic deformation response of friction-stir-welded dissimilar aluminum alloy joints: Strain localization effect." Journal of Materials Science & Technology 73, no. : 91-100.

Research articles
Published: 25 September 2020 in Science and Technology of Welding and Joining
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Linear friction welding was used to join Ti–3Al–8V–6Cr–4Mo–4Zr alloy under different pressures, and the microstructure, texture evolution and mechanical properties of the joint were investigated. Results show that the incomplete continuous dynamic recrystallisation (CDRX) occurs during welding, which refines the grains and produces a large number of subgrains in the thermo-mechanically affected zone (TMAZ) and weld centre zone (WCZ). At a higher friction pressure, the width of the WCZ becomes narrower, with the decrease of grain size and the increase of recrystallisation degree. In addition, the texture in the WCZ has changed from {112} to {110}, while the texture in the TMAZ remains at {110}. The tensile properties of the two joints are similar to the base metal (BM), and the microhardness in WCZ and TMAZ are also close to that in BM due to the incomplete CDRX and the decrease of alpha phase.

ACS Style

Xinyu Wang; Wenya Li; Qing Ye; Xiawei Yang; Tiejun Ma; Achilles Vairis. Linear friction welding of a beta titanium alloy: experimental investigations on microstructure evolution and mechanical properties. Science and Technology of Welding and Joining 2020, 25, 1 -12.

AMA Style

Xinyu Wang, Wenya Li, Qing Ye, Xiawei Yang, Tiejun Ma, Achilles Vairis. Linear friction welding of a beta titanium alloy: experimental investigations on microstructure evolution and mechanical properties. Science and Technology of Welding and Joining. 2020; 25 (8):1-12.

Chicago/Turabian Style

Xinyu Wang; Wenya Li; Qing Ye; Xiawei Yang; Tiejun Ma; Achilles Vairis. 2020. "Linear friction welding of a beta titanium alloy: experimental investigations on microstructure evolution and mechanical properties." Science and Technology of Welding and Joining 25, no. 8: 1-12.

Journal article
Published: 21 September 2020 in Journal of Manufacturing Processes
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An improved tool was designed to enhance weld formation for adjustable-gap bobbin-tool friction stir welding. No macro defects are observed as the welding speed increases from 120 to 240 mm/min. Microstructure analysis shows the maximum density of geometrically-necessary dislocations reaches 2.52 ×1013m-2 presenting at the stir zone (SZ). The Guinier-Preston-Bagaryatsky zones in heat affected zone (HAZ) and SZ are partially dissolved, and the relative volume fraction of S and θ phases in SZ is larger than that in HAZ. The hardness of the joints exhibits a W-shaped distribution. The minimum hardness is obtained at the HAZ. As the welding speed increases, the tensile strength initially increases up to 400 MPa at 180 mm/min, and then decreases. Poor mechanical properties at 60 mm/min and 300 mm/min are related to void defect.

ACS Style

D. Wu; W.Y. Li; Y.J. Gao; J. Yang; Y. Su; Q. Wen; A. Vairis. Effect of an improved pin design on weld formability and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al-Cu aluminum alloy joints. Journal of Manufacturing Processes 2020, 58, 1182 -1188.

AMA Style

D. Wu, W.Y. Li, Y.J. Gao, J. Yang, Y. Su, Q. Wen, A. Vairis. Effect of an improved pin design on weld formability and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al-Cu aluminum alloy joints. Journal of Manufacturing Processes. 2020; 58 ():1182-1188.

Chicago/Turabian Style

D. Wu; W.Y. Li; Y.J. Gao; J. Yang; Y. Su; Q. Wen; A. Vairis. 2020. "Effect of an improved pin design on weld formability and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al-Cu aluminum alloy joints." Journal of Manufacturing Processes 58, no. : 1182-1188.

Journal article
Published: 17 August 2020 in Chinese Journal of Aeronautics
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Hot compressive experiments of the laser solid formed (LSFed) TC4 titanium alloy were conducted at a wide temperature range of 650–950 °C and strain rate of 0.01–10 s−1. The Arrhenius-type constitutive models of the LSFed TC4 alloy were established at the temperature range of 800–950 °C and of 650–800 °C, respectively. The average relative error between the predicted stresses and experimental values in those two temperature ranges are 10.4% and 8.3%, respectively, indicating that the prediction models constructed in this paper are in a good agreement with experimental data. Processing maps were established by the principle of dynamic materials modeling on the basis of the data achieved from the hot compression experiments. The processing parameters corresponding to the stable and unstable regions of material deformation can be determined from the processing maps. The microstructure evolution of the stable and unstable regions of the samples after tests were observed. Finally, the effect of hot compressive parameters on the microstructure were investigated to research the dynamic recrystallization and the texture of the deformed LSFed TC4 alloy.

ACS Style

Xiawei Yang; Yanying Wang; Xiurong Dong; Chong Peng; Baijin Ji; Yaxin Xu; Wenya Li. Hot deformation behavior and microstructure evolution of the laser solid formed TC4 titanium alloy. Chinese Journal of Aeronautics 2020, 34, 163 -182.

AMA Style

Xiawei Yang, Yanying Wang, Xiurong Dong, Chong Peng, Baijin Ji, Yaxin Xu, Wenya Li. Hot deformation behavior and microstructure evolution of the laser solid formed TC4 titanium alloy. Chinese Journal of Aeronautics. 2020; 34 (5):163-182.

Chicago/Turabian Style

Xiawei Yang; Yanying Wang; Xiurong Dong; Chong Peng; Baijin Ji; Yaxin Xu; Wenya Li. 2020. "Hot deformation behavior and microstructure evolution of the laser solid formed TC4 titanium alloy." Chinese Journal of Aeronautics 34, no. 5: 163-182.

Article
Published: 15 August 2020 in International Journal of Minerals, Metallurgy, and Materials
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Two dissimilar steel plates, structural steel and mild steel, were joined by explosion welding to form a composite. The composite was then heat-treated by quenching at 840°C for 30 min followed by tempering at 200°C for 3 h. The microstructure was investigated under an optical microscope and a scanning electron microscope. The mechanical properties were measured using Vickers microhardness and Charpy impact tests. The results show a deformed interface with typical wave features at the welding zone, but no defects were observed. Moreover, the ferrite in the parent plate in the weld zone was elongated due to the strong plastic deformation from the explosion. After heat treatment, the hardness of the flyer plate (structural steel) was over HV0.2 800, while that of the parent plate (mild steel) was HV0.2 200. The increase in hardness was due to the presence of martensite. Moreover, the average impact energy was increased from 18.5 to 44.0 J following heat treatment; this is because of the formation of recrystallized grains at the weld interface, which is due to the dynamic recovery and local recrystallization, and the strong elemental diffusion that occurred between the two plates.

ACS Style

En-Ming Zhang; Yi-Ming Zhao; Zhong-Mou Wang; Wen-Ya Li. Effect of heat treatment on the microstructure and mechanical properties of structural steel-mild steel composite plates fabricated by explosion welding. International Journal of Minerals, Metallurgy, and Materials 2020, 27, 1115 -1122.

AMA Style

En-Ming Zhang, Yi-Ming Zhao, Zhong-Mou Wang, Wen-Ya Li. Effect of heat treatment on the microstructure and mechanical properties of structural steel-mild steel composite plates fabricated by explosion welding. International Journal of Minerals, Metallurgy, and Materials. 2020; 27 (8):1115-1122.

Chicago/Turabian Style

En-Ming Zhang; Yi-Ming Zhao; Zhong-Mou Wang; Wen-Ya Li. 2020. "Effect of heat treatment on the microstructure and mechanical properties of structural steel-mild steel composite plates fabricated by explosion welding." International Journal of Minerals, Metallurgy, and Materials 27, no. 8: 1115-1122.