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RISS 인기검색어
- 검색키워드
- 저자 : Junting Luo (검색결과 5 건)
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Junting Luo,Yahong Xue,Ke Chen,Yanpeng Shang,Chunxiang Zhang 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.1
Continuous integrated simulation of JCO forming, reducing gap, welding, and mechanical expanding processes of large-sized straight welded pipe is conducted using Marc software. Taking expanding ratio as variable, the residual stress distribution of weld bead and the influence rule of the expanding ratio are investigated before and after expansion. In thickness direction, in the bonding zone of pre-welding and outside weld, as well as at the bottom of the inside weld, the residual stress is large before expanding. The residual stress in the outside weld is large after expanding. The peak value of residual stress is decreased by about 61 to 78%. The expanding ratio is higher, the peak clipping effect becomes more evident, and residual stress becomes more uniform. The simulation results agrees with the test results, thus confirm that integrated simulation can achieve the visualization of residual stress evolution in the production process of large-sized straight welded pipe.
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Fabrication of High-Strength Mg–Gd–Nd–Zn–Sn–Zr Alloy via Extrusion and Aging
Yan Zehua,Yu Yandong,Qian Jiahao,Luo Junting,Sang Yanchao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
A high-strength Mg–9Gd–3Nd–1Zn–1Sn–0.5Zr (wt%) alloy bar was successfully fabricated by extrusion and followingaging two-steps processes, during which the alloy′s microstructures were determined to investigate the refinement mechanismduring extrusion and to reveal the morphology precipitation behavior of the as-extruded alloy after aging. Based on thecharacterization of the mechanical properties, the strengthening mechanism of the alloy under different treatment processeshad been discussed. Our results showed that the greater the extent of extrusion, the finer the grains and eutectic phase, andcrushing and dynamic recrystallization are the refinement mechanisms of the alloy in narrow-zone. After peak-aged treatmentat 200 °C, a large number of spherical β′ phase and lamellar precipitated phase had been observed, which replacesthe amorphous β" phase of the alloy was under-aged. The ultimate tensile strength, yield strength, and elongation were462.12 MPa, 391.97 MPa, and 4.2% respectively, and the increase number of the β′ phase and long-period stacking ordered(LPSO) phase were the reason why the strength of the alloy reached the highest value. At the over-aging stage (96 h), thesize of the lamellar precipitates and the LPSO was larger than that of the peak-aged, and the spherical β′ phase appeared inpeak-aging stage decreased significantly, which reduced its performance.
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Chunxiang Zhang,Hao Xue,Shiping Xing,Junting Luo 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.8
The electric field-assisted (EFA) heat treatment is proposed to solve the problem of excessive grain growth of β phase duringthe heat treatment of ZrTiAlV alloy. The effect of the EFA heat treatment process on the phase transformation and microstructureof the as-forged and severe plastic deformation (SPD) alloys are studied. For the as-forged 47Zr alloy, the pure βphase can be obtained by holding at 700 °C for 5 min. After SPD, the increase in defect concentration in the alloy reducesthe effectiveness of the EFA heat treatment, and required an extension of the holding time to 15 min to obtain a pure β phase. Furthermore, a new mechanism for the transition of needle-like α phase to β phase is proposed. Dislocations in the β-phasematrix shear the needle-like α phase, resulting in the formation of a large number of stacking faults inside it, which are thentransformed into the β phase through atomic plane slippage.
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Crystallization Toughening of Fe-Based Amorphous Alloys Under Strain–Heat Coupling Effect
Wei Zhao,Jiacheng Yu,Mindong Hu,Honglei Hu,Junting Luo,Gong Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.1
The crystallization toughening of Fe-based amorphous alloys under strain–heat coupling effect was studied. This effectinvolved annealing crystallization along with uniform plastic deformation under three-direction compressive stress. Resultsshowed that the Fe-based amorphous alloys subjected to strain–heat coupling action had greater toughening effect than thosesubjected to single low-temperature annealing. The difference was due to the change in morphology of the precipitated crystalphase and the substantial amount of free volume introduced into an amorphous matrix through uniform plastic deformation,which was conducive to the proliferation of shear bands. However, excessive plastic deformation led to direct fracture ofmaterials after elastic deformation.
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Yahong Xue,Jigang Chen,Xin Shi,Jichuan Yao,Junting Luo 한국섬유공학회 2018 Fibers and polymers Vol.19 No.3
A new parameterized finite element model was established for self-lubricating fabric liners in different weaving patterns. This model precisely simulated the spatial configuration of woven yarns with consideration of the cross-section deformation as well as the anisotropic material characteristics of yarns by converting the principal material direction along the yarn-path. Moreover, a set of simple and universal periodic boundary equations was proposed to solve the problem of the overabundance restriction in the boundary surfaces. To verify the validation of the finite element method proposed in this paper, an experimental prediction on elastic constants of self-lubricating fabric liners was carried out. The results indicate that the finite element model can successfully predict the macro mechanical properties of self-lubricating fabric liners with periodical structures. Based on the finite element model, the distributions of stress and strain, as well as the effects of weaving type and weaving density on the elastic modulus of fabric liners were investigated in details.
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