Browsing by Author "Wang, Jun"

Now showing 1 - 13 of 13
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    Additive manufacturing of a functionally graded high entropy alloy using a hybrid powder-bed wire-based direct energy deposition approach
    (Elsevier, 2023-01-23) Lu, Yao; Wang, Jun; Williams, Stewart; Zhu, Lisong; Ding, Jialuo; Diao, Chenglei; Jiang, Zhengyi
    A functionally graded AlxCoCrFeNi high entropy alloy with a variation in Al concentration along the building direction was in-situ produced using a hybrid powder-bed wire-based direct energy deposition process. A continuous transition from a single FCC structure to a major BCC+minor FCC dual-phase structure was achieved, benefiting from the remelting and reheating process during the deposition. In the FCC→BCC transition zone, the dendritic core region is identified as an FCC matrix decorated by AlNi-rich ordered B2 precipitates. The interdendritic area shows B2 precipitating in the FeCr-rich disordered A2 matrix. Additionally, the interface between the two regions shows that the A2 phase and ordered Cr3Fe intermetallic phase precipitate at the B2 phase. The mechanical properties show a tendency for higher strength and hardening rate but lower plasticity corresponding to the areas with higher Al content. Through quantitative estimation of different strengthening mechanisms, the contribution from precipitation strengthening became increasingly apparent as Al content increased. Other strengthening modes, including solid solution and dislocations, also contribute to the total strength. This investigation realises a novel additive manufacturing method combining powder bed and wire feeding, which can produce a more convenient and cost-effective gradient material with a complex composition.
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    Data supporting "A novel cold wire gas metal arc (CW-GMA) process for high productivity additive manufacturing"
    (Cranfield University, 2023-06-30 11:53) Wang, Chong; Wang, Jun; Bento, João; Ding, Jialuo; Rodrigues Pardal, Goncalo; Chen, Guangyu; Qin, Jian; Suder, Wojciech; Williams, Stewart
    This is a supplementary figure, showing the experimental setup for building the large-scale component with the CW-GMA process: (a) experiment setup, and (b) monitors for thermal camera and process camera.
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    Densification mechanism of Ti-Al-Nb alloys pressurelessly sintered from Al-Nb master alloy powder for cost-effective manufacturing
    (Elsevier, 2022-12-06) Liu, Xuzhen; Wang, Jun; Li, Yanmo; Li, Shukui; Cai, Qi
    Pressureless sintering is a cost-effective method to fabricate shaped Ti-Al-Nb alloy components in the aerospace industry. However, the sintering pores in the Ti-Al-Nb alloys led to inferior mechanical properties when using elemental Al powder as the raw material. By completely replacing the Al powder with the Al-Nb master alloy powder, the pores were substantially reduced in the pressurelessly sintered Ti-22Al-17.5Nb (at%) alloy, accompanied by the improvement of the tensile strength. We investigated the densification mechanisms by implementing the isothermal quenching experiments at 500–1200 °C. In the Ti/Al/Nb compact, the pores originated from the melting of Al and the Kirkendall effect at the interfaces of the Ti3Al and Nb particles. The transitions of Ti + 3Al → TiAl3 and α2 → B2 determined the porosity of the sintered alloy. In the Ti/Al-Nb/Nb compact, the Kirkendall pores at the Ti/Al3Nb interfaces were reduced since the diffusion of Al in Ti was retarded. The accelerated diffusion of Nb in Ti3Al suppressed the Kirkendall effect at the Nb/Ti3Al interfaces and promoted the formation of the B2 phase. The ripening of the B2 grains further contributed to the densification of the sintered alloy.
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    Enhanced performance of micro deep drawing through the application of TiO2 nanolubricant and graphene lubricants on SUS 301 stainless steel foil
    (MDPI, 2023-10-23) Pan, Di; Zhang, Guangqing; Jia, Fanghui; Lu, Yao; Wang, Jun; Li, Zhou; Li, Lianjie; Yang, Ming; Jiang, Zhengyi
    first_pagesettingsOrder Article Reprints Open AccessArticle Enhanced Performance of Micro Deep Drawing through the Application of TiO2 Nanolubricant and Graphene Lubricants on SUS 301 Stainless Steel Foil by Di Pan 1ORCID,Guangqing Zhang 1,Fanghui Jia 1,Yao Lu 2,Jun Wang 2,Zhou Li 3,Lianjie Li 4,Ming Yang 5ORCID andZhengyi Jiang 1,* 1 School of Mechanical, Materials, Mechatronic and Biomedical Engineering, Wollongong, NSW 2522, Australia 2 Welding Engineering and Laser Processing Centre, Cranfield University, Bedfordshire MK43 0AL, UK 3 College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China 4 School of Intelligent Manufacturing and Control Engineering, Shanghai Polytechnic University, Shanghai 201209, China 5 Graduate School of System Design, Tokyo Metropolitan University, Hino, Tokyo 191-0055, Japan * Author to whom correspondence should be addressed. Processes 2023, 11(10), 3042; https://doi.org/10.3390/pr11103042 Received: 2 September 2023 / Revised: 17 October 2023 / Accepted: 20 October 2023 / Published: 23 October 2023 (This article belongs to the Special Issue Processing, Manufacturing and Properties of Metal and Alloys) Downloadkeyboard_arrow_down Browse Figures Versions Notes Abstract In recent years, the quest for effective lubrication in micro deep drawing (MDD) has seen promising advancements. In this study, the influence of TiO2 nanolubricants and graphene lubricants on the performance of 301 stainless steel foil in MDD is examined. The MDD undergoes an extensive evaluation of various lubrication conditions, including dry, TiO2 nanolubricant, graphene lubricant at concentrations of 2.5 mg/mL, 5.0 mg/mL, and 10.0 mg/mL, as well as combined applications of TiO2 and graphene lubricants. Utilising a 5.0 mg/mL graphene lubricant together with TiO2 nanolubricants led to a significant reduction in drawing force, highlighting the synergistic efficacy of this combined lubricant. A pronounced enhancement in the consistency of the produced microcups was also attained. These results emphasise the promise of TiO2 nanolubricant and graphene lubricants in optimising the MDD process.
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    Ex situ analysis of high-strength quenched and micro-alloyed steel during austenitising bending process: numerical simulation and experimental investigation
    (Springer, 2022-05-11) Lu, Yao; Xie, Haibo; Wang, Jun; Jia, Fanghui; Lin, Fei; Zhou, Cunlong; Xu, Jianzhong; Han, Jingtao; Jiang, Zhengyi
    This paper compares the microstructure and mechanical evolution in a high-strength quenched and micro-alloyed steel during the austenitising bending process. Simulation results indicated a new finding that the stress neutral layer (SNL) tends to move to the tension zone during straining. The hardness gradient detected from the centre to compression/tension zones was resulted from comprehensive factors: First of all, the location of SNL revealed a prominent impact on strength. Second, the dislocation accumulation would be responsible for the hardness gradient on the surfaces. In addition, the overall strength decrease during straining was mainly ascribed to integrated effects of dynamic recovery (DRV) and dynamic recrystallisation (DRX). Apart from that, overall smaller martensite packet size and coarser prior austenite grains resulted in the increased hardness value at a lower bending degree. Also, the high consistency between experimental and simulation results is instructive for the practical forming process of railway spring fasteners.
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    Forming rate dependence of novel austenitising bending process for a high-strength quenched micro-alloyed steel: experiments and simulation
    (MDPI, 2025-02-06) Lu, Yao; Wang, Jun; Li, Zhou; Lin, Fei; Pan, Di; Jia, Fanghui; Han, Jingtao; Jiang, Zhengyi
    This austenitising bending investigation was carried out in a vacuum environment with the forming rates of 1, 10, and 100 mm/min under a certain bending temperature of 900 °C by a thermomechanical simulator. The enhanced strength at the accelerated forming rate and on the compression/tension zones throughout the thickness of the bent plates was discussed in detail in terms of dislocation pile-up, smaller prior austenite grain size, dynamic recrystallisation, smaller martensite packet, and stress-neutral layer. Since the simulation results were validated to match the experimental trend, this investigation could be applied as a valuable reference to simulate the practical manufacturing process of railway fasteners.
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    HAZ effects in hot-rolled dual-phase steel during flash butt welding of wheel rims
    (Springer, 2023-09-29) Han, Jian; Zhu, Lisong; Wang, Jun; Zhang, Caidong; Sun, Li; Zhang, Zhigiang; Ma, Cheng; Jiang, Zhengyi; Linton, Valerie
    The embrittlement and softening behavior in simulated heat-affected zones (HAZ) of a newly designed dual-phase DP680 steel for wheel rim applications with different flash allowances were investigated to determine weldability, and offer valuable information for the steel design and its subsequent flash butt welding (FBW). The characterization of microstructure and mechanical performance for the simulated HAZ was conducted by means of optical microscopy, scanning electron microscopy, electron backscatter diffraction, hardness distribution, and Charpy V-notch (CVN) values at selected temperatures. The investigation demonstrates that the toughness of coarse-grained HAZ was kept at an average level of 25.3 J when the prior austenite grain size was controlled to 60.54 μm at a flash allowance of 14 mm (equivalent to heat input of 15.14 kJ/cm based on real welding process), which exhibits the worst toughness when the flash allowance was changed from 4 to 14 mm. Further, with a higher martensite fraction (> 30 pct) in base material (BM), the softening occurs in inter-critical HAZ (ICHAZ) instead of sub-critical HAZ since most of martensite in ICHAZ has decomposed, and the rest ferrite and newly formed bainite with remaining martensite reduce the hardness to a larger extent compared to SCHAZ, whose martensite has only partly decomposed. Even if the softening degree is up to 21.6 pct compared to the BM (average 233 HV0.5), the work hardening during a series of forming processes after FBW has alleviated the softening evidently (work hardening degree > 10 pct). However, the failure location is still in ICHAZ after forming extension which has been confirmed in practical applications of DP680 FBW and subsequent forming processes.
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    Investigation of 300M ultra-high-strength steel deposited by wire-based gas metal arc additive manufacturing
    (Springer, 2023-11-01) Wang, Jun; Diao, Chenglei; Taylor, Mark; Wang, Chong; Pickering, Ed J.; Ding, Jialuo; Pimentel, Misael; Williams, Stewart
    300 M ultra-high-strength steel (UHSS) is widely used to produce landing gear components for aircraft. The conventional manufacturing route for these components involves extensive machining and significant material wastage. Here, the application of wire-based gas metal arc additive manufacturing to produce 300 M UHSS parts was investigated. In particular, the influence of torch shielding atmosphere on the process stability and material performance of 300 M UHSS was investigated. The shielding gases used for comparison are pure Ar, Ar with 2.5% CO2, Ar with 8% CO2, Ar with 20% CO2, and Ar with 2% CO2 and 38% He. It was found that the arc length decreased, the transfer mode changed from spray to droplet mode, and spattering became more severe as the CO2 proportion increased. Additionally, replacing Ar with He led to a broader arc core, and a slightly shorter arc length and maintained a spray transfer, which decreased spatter. The wall surface roughness followed the trend in spatter, becoming worse with the increasing CO2 proportion, and better with He addition. Adding CO2 and He in pure Ar significantly increased the bead and wall width. The microstructure and mechanical properties exhibited a strong location dependence in the as-built state, with fresh martensite and higher strength in the top region, and tempered martensite and better ductility in the reheated bulk. Generally, torch shielding gas composition appeared to have no significant effect on the microstructure evolution. This study provides a reference for the subsequent application of gas metal arc additive manufacturing to aircraft landing gear mass production to achieve a high deposition rate and process stability simultaneously.
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    A novel cold wire gas metal arc (CW-GMA) process for high productivity additive manufacturing
    (Elsevier, 2023-07-01) Wang, Chong; Wang, Jun; Bento, João; Ding, Jialuo; Rodrigues Pardal, Goncalo; Chen, Guangyu; Qin, Jian; Suder, Wojciech; Williams, Stewart
    Wire-arc directed energy deposition (DED) is suitable for depositing large-scale metallic components at high deposition rates. In order to further increase productivity and efficiency by reducing overall manufacturing time, higher deposition rates are desired. However, the conventional gas metal arc (GMA) based wire-arc DED, characterised by high energy input, normally results in high remelting and reheating at relatively high deposition rates, reducing the process efficiency and deteriorating the mechanical performance. In this study, a novel wire-arc DED process with the combination of a GMA and an external cold wire, namely cold wire-gas metal arc (CW-GMA), was proposed for achieving high deposition rate and low material remelting. The maximum deposition rates at different levels of energy input were investigated, with the highest deposition rate of 14 kg/h being achieved. An industrial-scale component weighing 280 kg was built with this process at a high deposition rate of around 10 kg/h, which demonstrated the capability of the process for high productivity application. It was also found that, due to the addition of the cold wire, the remelting was reduced significantly. The working envelope and geometric process model for the CW-GMA process was developed, which can be used to avoid defects in parameter selection and predict the geometry of single-pass wall structures. Moreover, the addition of the cold wire in the CW-GMA process reduced the specific energy density, leading to a reduction in both grain size and anisotropy, which improved the mechanical properties with increased strength and reduced anisotropy.
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    On the composition gradient of steel/Invar functionally graded material manufactured by wire-based direct energy deposition
    (Elsevier, 2024-09-25) Wang, Jun; Biswal, Romali; Chen, Guangyu; Pardal, Goncalo Rodrigues; Lu, Yao; Ding, Jialuo; Williams, Stewart
    This study utilized double-wire plasma arc direct energy deposition to produce functionally graded materials (FGMs) with two transition designs, abrupt (AT) and gradual (GT), from Er90s steel to Invar. The study systematically compared the transition in chemical composition, microstructure, phase evolution, thermal stress, and mechanical performance. Both FGM types exhibited a band structure in the Er90s section and coarse columnar grains in the Invar section, with the AT deposit showing a 1 mm thick, defect-free interface and the GT deposit having an 18 mm thick transition region with distinct boundaries. It revealed diverse microstructures across the transition zones, including fine ferrite, martensite with minor retained austenite (RA), coarse columnar austenite with martensite dendrites, and single FCC austenite. The GT sample uniquely featured a microstructure of martensite laths inside prior austenite decorated by RA semicontinuous network, with a crack detected due to dilatational stresses from martensite transformation. Hardness was similar in both FGM types, with higher values at the interfaces, especially in the GT FGM. The GT FGM demonstrated higher strength but lower ductility compared to the AT FGM, with failure occurring in the Invar portion for both. Thermal stress modelling indicated smoother stress transitions in the GT sample but no significant performance differences between Er90s and Invar. This study showcases the effectiveness of double-wire plasma arc DED in producing steel/Invar FGMs with varying composition gradients. It also underscores the importance of selecting the right mixing ratio for Er90s/Invar FGM deposits to avoid cracking and deterioration of properties in the gradient area.
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    Optimising two-stage vacuum heat treatment for a high-strength micro-alloyed steel in railway spring clip application: impact on microstructure and mechanical performance
    (MDPI, 2023-07-10) Lu, Yao; Wang, Jun; Pan, Di; Han, Jian; Zhu, Lisong; Diao, Chenglei; Han, Jingtao; Jiang, Zhengyi
    The heat treatment process is a vital step for manufacturing high-speed railway spring fasteners. In this study, orthogonal experiments were carried out to obtain reliable optimised heat treatment parameters through a streamlined number of experiments. Results revealed that a better comprehensive mechanical performance could be obtained under the following combination of heat treatment parameters: quenching temperature of 850 °C, holding time of 35 min, medium of 12% polyalkylene glycol (PAG) aqueous solution, tempering temperature of 460 °C, and holding time of 60 min. As one of the most important testing criteria, fatigue performance would be improved with increasing strength. Additionally, a high ratio of martensite to ferrite is proven to improve the fatigue limit more significantly. After this heat treatment process, the metallographic microstructure and mechanical properties satisfy the technical requirements for the high-speed railway practical operation. These findings provide a valuable reference for the practical forming process of spring fasteners.
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    Physical simulation and numerical simulation of flash butt welding for innovative dual phase steel DP590: a comparative study
    (MDPI, 2023-05-03) Song, Jingwen; Zhu, Lisong; Wang, Jun; Lu, Yao; Ma, Cheng; Han, Jian; Jiang, Zhengyi
    In this study, the microstructure and performance of newly designed dual-phase steel (DP590) after joining by flash butt welding (FBW) for vehicle wheel rims was analysed and compared by two simulations, i.e., physical simulation and numerical simulation, due to the high acceptance of these two methodologies. Physical simulation is regarded as a thermal–mechanical solution conducted by the Gleeble 3500 simulator and which can distribute the heat-affected zone (HAZ) of the obtained weld joint into four typical HAZs. These are coarse-grained HAZ, fine-grained HAZ, inter-critical HAZ and sub-critical HAZ. A combination of ferrite and tempered martensite leads to the softening behaviour at the sub-critical HAZ of DP590, which is verified to be the weakest area, and influences the final performance due to ~9% reduction of hardness and tensile strength. The numerical simulation, relying on finite element method (FEM) analysis, can distinguish the temperature distribution, which helps us to understand the relationship between the temperature distribution and real microstructure/performance. Based on this study, the combination of physical and numerical simulations can be used to optimise the flash butt welding parameters (flash and butt processes) from the points of temperature distribution (varied areas), microstructure and performance, which are guidelines for the investigation of flash butt welding for innovative materials.
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    Strain hardening and strengthening mechanism of laser melting deposition (LMD) additively manufactured FeCoCrNiAl0.5 high-entropy alloy
    (Elsevier, 2022-10-05) Zhu, Lisong; Geng, Keping; Wang, Jun; Sun, Da; Shan, Mengdie; Lu, Yao; Zhang, Xuesong; Cai, Yangchuan; Han, Jian; Jiang, Zhengyi
    In order to develop the high-entropy alloy (HEA) with low cost and excellent mechanical properties for structural applications, the FeCoCrNiAl0.5 HEA has been fabricated by laser melting deposition, one of the advanced additive manufacturing methods. Strain hardening behaviour has been analysed and discussed using the combination of characterisation techniques. The LMD-ed FeCoCrNiAl0.5 had a true yield strength and strain of ∼463 MPa and 2.94%. Also, the true tensile strength of the LMD-ed FeCoCrNiAl0.5 reached 876 MPa, together with the ductility of 24.97% (engineering strain). The LMD-ed FeCoCrNiAl0.5 HEA exhibited a dual-phase structure of 93% face-centred cubic (FCC) phase and 6.9% ordered B2 phase. The phase boundary between the disordered FCC and ordered B2 phases played a key role in the barrier, which can block the movement of dislocations because of the lattice distortion, very large angle, and mismatch of the lattice. Dislocation pile-up and tangle caused the dislocation density near the phase boundaries to be higher than that in other areas, meanwhile, they further prevented the movement of dislocation under stress as they generated back stress, therefore LMD-ed FeCoCrNiAl0.5 HEA had a good strain hardening behaviour with a strain hardening exponent of 0.92. This study provided an innovative insight into the development of HEAs with ordered phase by laser additive manufacturing for structural applications.