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Microstructure and mechanical properties of high-strength low alloy steel by wire and arc additive manufacturing

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International Journal of Minerals,Metallurgy and Materials 2020年第7期27卷 933-942页

作者： Yi-li Dai sheng-fu yu An-guo Huang yu-sheng shi State Key Laboratory of Material Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan 430074China

A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)*** microstructure characteristics and transformation were observed and *** results show that the forming part includes four *** solidification zone solidifies as typical columnar crystals from a molten *** complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100℃,and the typical columnar crystals in this zone are difficult to *** partial austenitizing zone forms from the completely austenite zone heated between Ac1(austenite transition temperature)and1100℃,which is mainly equiaxed *** several thermal cycles,the partial austenitizing zone transforms to the tempering zone,which consistes of fully equiaxed *** the solidification zone to the tempering zone,the average grain size decreases from 75 to20μ*** mechanical properties of HBMDPJ satisfies the requirement for the intended application.

关键词： wire and arc additive manufacturing high strength low alloy steel microstructure inclusions fine grain ferrite mechanical properties

Influence of high-temperature oxidation of SiC powders on curing properties of SiC slurry for digital light processing

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Journal of Advanced Ceramics 2023年第1期12卷 169-181页

作者： Zhang-Ao shi Jia-Min WU Zhi-Qiang FANG yu-sheng shi State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of EducationWuhan 430074China

Fabrication of silicon carbide(SiC)ceramics by digital light processing(DLP)technology is difficult owing to high refractive index and high ultraviolet(UV)absorptivity of SiC *** surface of the SiC powders can be coated with silicon oxide(SiO_(2))with low refractive index and low UV absorptivity via high-temperature oxidation,reducing the loss of UV energy in the DLP process and realizing the DLP preparation of the SiC ***,it is necessary to explore a high-temperature modification process to obtain a better modification effect of the SiC ***,the high-temperature modification behavior of the SiC powders is thoroughly investigated in this *** results show that nano-scale oxide film is formed on the surface of the SiC powders by short-time high-temperature oxidation,effectively reducing the UV absorptivity and the surface refractive index(nʹ)of the SiC *** the oxidation temperature is 1300℃,compared with that of unoxidized SiC powders,the UV absorptivity of oxidized SiC powders decreases from 0.5065 to 0.4654,and a curing depth of SiC slurry increases from 22±4 to 59±4μ***,SiC green bodies are successfully prepared by the DLP with the the oxidized powders,and flexural strength of SiC sintered parts reaches 47.9±2.3 MPa after 3 h of atmospheric sintering at 2000℃without any sintering aid.

关键词： silicon carbide(SiC)powders oxidation modification digital light processing(DLP) ultraviolet(UV)absorptivity curing depth

Microstructure and properties of silica-based ceramic cores by laser powder bed fusion combined with vacuum infiltration

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Journal of Materials Science & Technology 2023年第26期157卷 71-79页

作者： Jie Zhang Jia-Min Wu Heng Liu Wen Zheng Chun-sheng Ye shi-Feng Wen Chun-Ze Yan yu-sheng shi State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of EducationWuhan 430074China

The silica-based ceramic core has attracted much attention in the preparation of hollow blades due to its great *** this paper,the silica-based ceramic cores reinforced with ZrSiO_(4) were prepared by laser powder bed fusion(LPBF)combined with vacuum infiltration(VI).To enhance the infiltration effect,the pre-sintered bodies with high porosity and hydrophilicity were obtained by pre-sintering at 1100℃.Results showed that a large number of silica particles infiltrated into the pre-sintered *** infiltrated silica promoted the generation of liquid phase in sintering,thereby promoting the removal of pores and the connection of ***,the dispersed ZrSiO_(4) grains prevented the viscous flow of the liquid phase,thereby increasing the ***_(4) grains could hinder the propagation of cracks due to their high *** the addition of ZrSiO_(4) was 10 wt.%,room-temperature flexural strength of silica-based ceramic cores infiltrated with slurry S1(the mass ratio of silica sol to silica powder was 10:1)reached 17.21 MPa due to the reinforcement of sintering ***,high-temperature flexural strength reached 13.90 ***,the pre-sintering process could greatly improve the mechanical properties of silica-based ceramic cores prepared by LPBF-VI technology.

关键词： Silica-based ceramic cores Laser powder bed fusion ZrSiO_(4) Pre-sintering Vacuum infiltration

Corrosion Behavior of the S136 Mold Steel Fabricated by Selective Laser Melting

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Chinese Journal of Mechanical Engineering 2018年第6期31卷 68-78页

作者： shi-Feng Wen Xian-Tai Ji Yan Zhou Chang-Jun Han Qing-Song Wei yu-sheng shi State Key Laboratory of Materials Processing and Die & Mold Technology School of Materials Science and Technology Huazhong University of Science and Technology Wuhan 430074 China Faculty of Engineering China University of Geosciences Wuhan 430074 China

The selective laser melting(SLM) method has a great potential for fabricating injection mold with complex structure. However, the microstructure and performance of the SLM molds show significantly di erent from those manufac?tured by traditional technologies. In this study, the microstructure, hardness and especially corrosion behavior of the samples fabricated by SLM and casting were investigated. The XRD results exhibit that the γ?Fe phase is only obtained in the SLM parts, and the α?Fe peak slightly moves to low di raction angle compared with casting counterparts. Due to the rapid cooling rate, the SLM samples have fine cellular microstructures while the casting ones have coarse grains with obvious elements segregation. Besides, the SLM samples show anisotropy, hardness of side view and top view are 48.73 and 50.31 HRC respectively, which are 20% higher than that of casting ones. Corrosion results show that the SLM samples have the better anti?corrosion resistance(in a 6% FeCl3 solution for 48 h) but the deeper corrosion pits than casting ones. Finally, the performance of the SLM molds could meet the requirement of injecting production. Moreover, the molds especially present a significant decrease(20%) of cooling time and increases of cooling uniform?ity due to the customized conformal cooling channels.

关键词： Selective laser melting S136 mold steel Corrosion behavior Conformal?cooling channels

Preparation and properties of T-ZnO_(w) enhanced BCP scaffolds with double-layer structure by digital light processing

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Journal of Advanced Ceramics 2022年第4期11卷 570-581页

作者： Ming-Zhu PAN Shuai-Bin HUA Jia-Min WU Xi yuAN Ze-Lin DENG Jun XIAO yu-sheng shi State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of EducationWuhan 430074China Department of Orthopedic Surgery Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China

Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone *** this work,T-ZnO_(w) enhanced biphasic calcium phosphate(BCP)scaffolds with triply periodic minimal surface(TPMS)-based double-layer porous structure were fabricated by digital light processing(DLP)with high *** of suspension was first discussed to obtain better printing *** sintering,T-ZnO_(w) reacts with b-tricalcium phosphate(β-TCP)to form Ca_(19)Zn_(2)(PO_(4))14,and inhibits the phase transition toα-*** the content of T-ZnO_(w) increasing from 0 to 2 wt%,the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress,and have the effect of pulling out as well as fracture ***,excessive whiskers will reduce the cure depth,and cause more printing defects,thus reducing the mechanical ***,T-ZnO_(w) accelerates the deposition of apatite,and the sample with 2 wt%T-ZnO_(w) shows the fastest mineralization *** good biocompatibility has been proved by cell proliferation *** confirmed that doping T-ZnO_(w) can improve the mechanical strength of BCP scaffolds,and keep good biological property,which provides a new strategy for better bone repair.

关键词： biphasic calcium phosphate(BCP) T-ZnO_(w) digital light processing(DLP) double-layer structure cure property mechanical strength

Non-Gaussian feature of the output field from a double qubit-cavity ultrastrong coupling system

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Communications in Theoretical Physics 2024年第7期76卷 30-36页

作者： sheng-wen Xu shi-yu Dai Teng Zhao Center for Quantum Science and Technology Jiangxi Normal UniversityNanchang 330022China

We investigate the non-Gaussian feature of radiation in a circuit quantum electrodynamics(QED)system where two qubits are strongly coupled to a single-mode *** the regime of ultrastrong coupling(USC),the rotating-wave approximation is not valid,and the Rabi Hamiltonian contains counter-rotating wave terms,leading to level crossing and avoided crossings in the energy *** further analyze the intensity-amplitude correlation of the output field in these two novel *** the USC regime,the creation and annihilation operators in the correlation function are replaced,allowing for the identification of non-Gaussian features in the output *** findings reveal that despite the absence of squeezing effects in the output light,significant non-Gaussian characteristics are ***,we demonstrate that as the driving or coupling strength increases,the non-Gaussian features of the output field become more *** suggests that USC systems hold broad potential applications in the realms of nonlinear optics and the generation of non-Gaussian states.

关键词： ultrastrong coupling non-Gaussian intensity-amplitude correlation

Phase evolution and properties of novel Al2O3-based poly-hollow microsphere (PHM) ceramics

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Journal of Advanced Ceramics 2016年第2期5卷 176-182页

作者： Jia-Min WU Ying CHEN Xiao-Yan ZHANG Qian HUANG Jin-Long YANG yu-sheng shi State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 ChinaState Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China

In this paper, novel Al2O3-based poly-hollow microsphere (PHM) ceramics were prepared using Si3N4 and Al2O3 PHMs as pore-forming agents. The effect of Si3N4 and Al2O3 PHMs with different percentages on properties of Al2O3-based PHM ceramics was investigated. Through adjusting percentage of Al2O3 PHMs, Al2O3-based PHM ceramics with enhanced properties are achieved. X-ray diffraction (XRD) results show that main phases of Al2O3-based PHM ceramics vary from beta-SiAlON (z value increases from 2.9 to 4) to Al2O3 with the increase of percentage of Al2O3 PHMs from 10% to 100%. The different phase compositions result in different properties of Al2O3-based PHM ceramics. With the increase of percentage of Al2O3 PHMs, porosity of Al2O3-based PHM ceramics gradually decreases, while their shrinkage, flexural strength, and fracture toughness firstly decrease and then increase. Using different kinds of ceramic PHMs as pore-forming agents, various novel and high-performance porous ceramics could be prepared via optimizing percentage of ceramic PHMs in the future.

关键词： porous ceramics poly-hollow microsphere (PHM) pore-forming agent phase evolution mechanical properties

Preparation of Al-Zn-Mg-Cu alloy semisolid slurry through a water-cooled serpentine pouring channel

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China Foundry 2019年第1期16卷 31-39页

作者： Wen-zhi Zhu Wei-min Mao Qing-song Wei Chen Hui yu-sheng shi State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan 430074China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

The semisolid slurry of Al-Zn-Mg-Cu alloy was prepared through a self-designed water-cooled copper serpentine pouring channel(WSPC) machine. Influences of pouring temperature, the number of turns and the cooling water flow rate on the microstructure of the semisolid Al-Zn-Mg-Cu alloy slurry were investigated. The results show that the semisolid Al-Zn-Mg-Cu alloy slurry with satisfactory quality can be generated by the WSPC when the pouring temperature is in the range between 680 ℃ and 700 ℃. At a given pouring temperature, the average grain size of primary α-Al decreases and the shape factor increases with the increase of the number of turns. When the cooling water flow rate is 450 L·h^(-1), the obtained semisolid slurry is optimal. During the preparation of the semisolid Al-Zn-Mg-Cu alloy slurry with low superheat pouring, the alloy melt has mixed inhibition and convection flow characteristics by "self-stirring". When the alloy melt flows through the serpentine channel, the chilling effect of the inner wall of the channel, the convection and mixed inhibition of the alloy melt greatly promote the heterogeneous nucleation and grain segregation. This effect destroys the dendrite growth mode under traditional solidification conditions, and the primary nuclei gradually evolve into spherical or nearspherical grains.

关键词： Al-Zn-Mg-Cu Alloy semisolid slurry water-cooled serpentine channel primary α-Al

Study of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by a novel DCC-HVCI method

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Journal of Advanced Ceramics 2018年第2期7卷 152-159页

作者： Jia-Min WU Huan XIAO Meng-yue LIU Ying CHEN Yi-Xin MA Li-Jin CHENG yu-sheng shi State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and EngineeringHuazhong University of Science and Technology

In this paper, in-situ coagulation of 0.9Al_2O_3–0.1TiO_2 suspension and microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by a novel direct coagulation casting via high valence counter ions(DCC-HVCI) method were proposed. The 0.9Al_2O_3–0.1TiO_2 suspension could be coagulated via controlled release of calcium ions from calcium iodate at an elevated temperature. The influence of tri-ammonium citrate(TAC) content, solid loading, and calcium iodate content on the rheological properties of the suspension was investigated. In addition, the influence of coagulation temperature on coagulation time and properties of green bodies was also studied. It was found that the stable 0.9Al_2O_3–0.1TiO_2 suspension could be successfully prepared by adding 0.3 wt% TAC and adjusting pH value to 10–12 at room temperature. 0.9Al_2O_3–0.1TiO_2 green bodies with uniform microstructures were coagulated by adding 8.0 g/L calcium iodate after treating at 70 ℃ for 1 h. 0.9Al_2O_3–0.1TiO_2 ceramics, sintered at 1500 ℃ for 4 h and annealed at 1100 ℃ for 5 h, showed uniform microstructures with density of 3.62±0.02 g/cm^3. The microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by DCC-HVCI method were: ε_r = 11.26±0.06, Q×f = 11569± 629 GHz, τ_t = 0.93±0.60 ppm/℃. The DCC-HVCI method is a novel and promising route without binder removal process to prepare complex-shaped microwave dielectric ceramics with uniform microstructures and good microwave dielectric properties.

关键词： rheological properties microwave dielectric properties 0.9Al2O3–0.1TiO2 DCC-HVCI