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[Forum] Study of the Relationship between the Mongolian Word “Orda” and the English Word “Horde”
Hongge,Jiruhe,Surigalatu 단국대학교 몽골연구소 2016 Mongolian Survey Vol.6 No.1
This paper takes its initial measure from the historical linguistics and tries to further illustrate the fact on the social—cultural history of the two words “orda” and “horde” in order to make clear that the English word “horde” has some historical relation to the Mongolian word “orda”.
Effect of Strain Rate on the Microstructure and Texture Evolution of the ZK60 Alloy Sheets
Hongge Yan,Qin Wu,Jihua Chen,Weijun Xia,Min Song,Bin Su,Biao Huang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3
The dynamic recrystallization (DRX), precipitation and texture evolution of the ZK60 alloy sheets rolled at 300 °C withdifferent strain rates were studied, and the effects of texture on the plasticity were also clarified. The DRX grain sizes at fivestrain rates (5–25 s−1) are 1.4 μm, 1.2 μm, 1.8 μm, 2.4 μm and 2.8 μm, respectively, while the DRX volume fractions are35.8%, 75.0%, 82.0%, 88.0% and 93.0%, respectively. The maximum intensity values of the (0002) texture are 7.91, 8.22,7.64, 5.76 and 5.34 at five strain rates, respectively. The strongest (0002) texture is observed at the strain rate of 10 s−1,which is related to the relatively low DRX volume fraction and the precipitation density. The tensile strength (UTS) and yieldstrength (YS) increases firstly and then decreases, while the elongation (EL) gradually increases with increasing the strainrate, suggesting that the plasticity of the alloy sheet can be improved by decreasing the basal texture intensity and increasingthe dispersion degree of the basal texture. The optimal comprehensive mechanical properties are obtained at the strain rateof 10 s−1, with UTS of 358 MPa, YS of 291 MPa and EL of 21.5%.
Hongge Yan,Xiaole Gong,Jihua Chen,Meixin Cheng 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
Microstructure, texture characteristics, mechanical and bio-corrosion properties of the Mg–5Zn–xSr alloys (x=0, 0.2, 0.6,1.0) prepared by high strain rate rolling are carefully studied. A low level of Sr addition enhances dynamic precipitationof nano-scale MgZn2 particles in the as-rolled Mg–5Zn alloy, with 0.6%Sr showing the maximum efciency. These highdensity MgZn2 particles can pin grain boundaries of dynamic recrystallization grains and inhibit their growth. A low levelof Sr addition (≤0.6%) enhances the (0002) basal texture, but 1.0%Sr is just the reverse. The as-rolled Mg–5Zn–0.6Sr alloyexhibits the best combination of ultimate tensile strength (359 MPa) and elongation to rupture (20%). The high strength canbe attributable to a reduced grain size, precipitation and basal texture strengthening. The Mg–5Zn–xSr alloys exhibit excellent bio-corrosion resistance, but a minor Sr addition cannot bring about further bio-corrosion resistance improvement dueto the multiple actions of grain size, DRX degree, dynamic precipitates and texture characteristics. The 0.6%Sr addition cangreatly improve the strength of the as-rolled alloy at no expense of bio-corrosion resistance.
Yang Liao,Hongge Yan,Weijun Xia,Jihua Chen,Bin Su,Xinyu Li,Lu Zhao 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4
High strain rate rolling (HSRR) is developed to improve the strength, plasticity and stress corrosion resistance of 7050 aluminumalloy simultaneously. The volume fraction of the small-angle grain boundary in the HSRRed alloy sheet is 89.9%. TEM shows that the presence of dislocations and sub-grains promotes the precipitation of the second phase. The alloy inthe T6 state has the highest strength (622 MPa) and the biggest elongation to rupture (20.6%), but poor corrosion resistance. The over-aged state shows the best corrosion resistance. The RRA state can achieve the tensile strength equivalent to T6 of614 MPa, the highest yield strength of 561 MPa and corrosion resistance comparable to the over-aged state. TEM observationshows the existence of sub-grains and dislocations plays an important role in the nucleation of the second phase. Thehigh strength can be attributed to the higher volume fraction of the precipitates, and the high plasticity can be attributed tothe higher work hardening rate. The better corrosion resistance can be ascribe to the wider precipitate-free zones at the grainboundary and the presence of the larger size second phase particles.
Effect of Mg Content on the Damping Behavior of Al–Mg Alloys
Zhenzhen Li,Hongge Yan,Jihua Chen,Weijun Xia,Bin Su,Lu Zhao,Min Song 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9
This article investigated the effect of Mg content (4.5, 6.5 and 9.2, in wt%) on the damping capacities of Al–Mg alloys. The results indicate that the damping behavior can be divided into three regions. Region I refers to the low strain amplituderegion (ε < 5 × 10−5), where the damping capacity decreases with increasing the Mg content and has almost no relation withthe strain amplitude. Region II is the middle strain amplitude region (5 × 10−5 < ε < 8 × 10−4), where the damping capacityincreases rapidly with the strain. Region III refers to the high strain amplitude region (8 × 10−4 < ε < 2 × 10−3), where thedamping capacity remains constant and is independent of the strain when the strain is high enough, but increases with the Mgcontent. The damping values Q−1 of Al–4.5Mg, Al–6.5Mg and Al–9.2Mg alloys are 0.01501 ± 0.00032, 0.01633 ± 0.00032and 0.01862 ± 0.00119 at the strain of 1 × 10−3, respectively. The damping capacity in Region I is mainly determined bythe lattice distortion caused by Mg addition and the restoring force caused by pinning points and Suzuki segregation. Theextended dislocations break away from the pinning effect of Mg atoms and become moveable in Region II, and the movementof extended dislocations is the dominant damping mechanism in Region III.
Wensen Huang,Jihua Chen,Hongge Yan,Weijun Xia,Bin Su,Weijun Zhu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.6
The Mg–xGa (x = 1, 2, 3 and 5 in mass%) alloys are subjected to high strain rate rolling (HSRR) at 275 °C with the rollingstrain rate of 9.1 s−1 to develop high performance Mg alloy sheets with high plasticity. Effects of Ga content on microstructureand mechanical properties of the Mg–Ga alloys are investigated by SEM, XRD, tensile testing and etc. The Ga additioncan reduce the critical strain of DRX in Mg alloys, which is associated with the reduced stacking fault energy, the increasedtwinning density during deformation and the more DRX nucleation sites during HSRR. With the Ga content increasing from2 to 3%, the reduced DRX degree is attributable to the hindrance of dynamic precipitates. With the Ga content increasingfrom 3 to 5%, the slightly increased DRX degree can be ascribed to the relatively coarse precipitates. The Mg–2 Ga alloysheet, featured with complete DRX, exhibits an ultra-high plasticity (with the elongation to rupture of 36.6%) and a relativelylow anisotropy of yield strength and plasticity. The Mg–5 Ga alloy sheet has the best comprehensive mechanical properties,with the ultimate tensile strength of 292 MPa, yield strength of 230 MPa and elongation to rupture of 30.3%, which can beascribed to the combination of grain refinement strengthening and precipitation strengthening.
Effects of Zn Addition on Dynamic Recrystallization of High Strain Rate Rolled Al–Mg Sheets
Lu Zhao,Weijun Xia,Hongge Yan,Jihua Chen,Bin Su 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5
Effects of Zn addition (0, 0.5, 1.0 and 1.5 wt%) on dynamic recrystallization (DRX) behavior of Al-9.2Mg alloy during highstrain rate rolling (with rolling temperature of 400 °C and strain rate of 8.6 s−1) are carefully investigated. The Zn contentplays a significant role in the enhanced DRX of Al-9.2Mg alloy. The critical strain (εc) and the peak strain (εp) are reducedfrom 0.178 ± 0.002 to 0.102 ± 0.001 and 0.211 ± 0.003 to 0.139 ± 0.002 with the Zn content increasing from 0 to 1.5%,respectively. Almost complete DRX grains are obtained in the Al-9.2Mg-0.5Zn alloy. The DRX volume fraction (FDRX), theaverage DRX grain size (AGS), the volume fraction of high-angle grain boundaries (FHAGBs) and the average grain boundaryangle (θAV) are 91.5%, 5.6 μm, 91.1% and 37.6 º, respectively. The Zn addition can enhance the formation of deformationbands (DBs) and promote the DRX process by providing the nucleation sites for new grains, while the increased dynamicprecipitates inhibit DRX. Continuous dynamic recrystallization (CDRX) is the dominant DRX mechanism, while discontinuousdynamic recrystallization (DDRX) is also existent. Effects of Zn addition on DRX process of the Al–Mg alloys canbe ascribed to the more DBs, the reduced stacking fault energy (SFE) and the dynamic precipitates.
Xinyu Li,Weijun Xia,Jihua Chen,Hongge Yan,Zhenzhen Li,Bin Su,Min Song 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12
A bimodal grain distribution is generated in the Al-6.5Mg alloy deformed by high strain rate rolling (HSRR) at 320 °C, inwhich the fine grains with the average size of 2.1 μm and the coarse grains with the size of hundreds of microns containingultrafine sub-grains are developed. The deformed microstructures are detected by transmission electron microscopy, X-raydiffraction and electron backscattered diffraction. High strength and considerable ductility are achieved in the HSRRed alloyand the high strength is ascribed to solution strengthening, grain (sub-grain) strengthening and dislocation strengthening. The grain (sub-grain) strengthening is the dominant contributor (~ 146 ± 6 MPa) for yield strength. The generation of newfine grains is primarily observed along the deformation bands related to the high Mg solid content and the high strain rate at320 °C. The dynamic recrystallization related to the deformation bands is proposed to build the bimodal grain distributionfor achieving high strength and considerable ductility.
Experimental study of the influence of sodium salts as additive to NOxOUT process
Zhaoping Zhong,Xiujin Liang,Baosheng Jin,Xiaolin Chen,Weiling Li,Hongge Wei,Houkun Guo 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.5
An experimental study of the SNCR process with urea as reducing agent and sodium salts as additive has been carried out, and detailed analysis of the reaction mechanism has been given here. In the temperature range of 800-975 oC, NO concentration decreases at first and then increases while the concentration of N2O increases at first and then decreases with the increasing of temperature, and the turning point is 900 oC. With increasing of normalized stoichiometric ratio of reduction nitrogen to NOx (NSR), NO removal efficiency increases, while the concentration of N2O also increases, which decreases overall NOx removal efficiency. With sodium salts as additive, the concentration of N2O decreases with increasing of sodium salts addition at all temperatures, while the concentration of NO decreases at first and then increases at low-temperature side of the temperature window and increases at high-temperature side with additional increasing, whose changing extent is smaller than N2O. Since sodium salts as additive can remove N2O effectively and have no large influence on the removal of NO, the effect of sodium salts as additive is the combined effect of the production of active radicals and the removal of HNCO produced by the decomposition of urea through neutralization reactions, which is more important. To achieve the same effect under each condition, the needed addition of NaOH and CH3COONa is less than that of Na2CO3 counting as Na atom. For the decomposition of CH3COONa can produce CH3COO, its addition can promote the reduction of NO more obviously at the lower temperature than Na2CO3 or NaOH. Overall NOx removal efficiency at 900 oC with NSR=1.5 had been improved from about 30% to 70.45% through the addition of sodium salts. Sodium salts as additive caused the flue gas to become alkaline gas, but it was not serious for sodium salts existing as NaNCO.