Xiao Zhao

University of Southampton

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Yusheng Shi

Huazhong University of Science and Technology

Yu Xia

Guangxi University of Science and Technology

Shoufeng Yang

University College London

Neil W. Bressloff

University of Southampton

Nong Gao

University of Southampton

Bo Song

Huazhong University of Science and Technology

Zhong Qing Zhang

Guangxi University

Qingsong Wei

Huazhong University of Science and Technology

Anqi Liang

Fujian Normal University

Shifeng Wen

Huazhong University of Science and Technology

Cooperative Institutions

Huazhong University of Science and Technology

Southwest Jiaotong University

University of Southampton

Shenyang Jianzhu University

Intelligent Health (United Kingdom)

China Agricultural University

Chinese Academy of Sciences

Nanjing University of Aeronautics and Astronautics

Nanjing Agricultural University

Shanghai Jiao Tong University

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Development of 3-D Printed Silica Preforms

Angeles L. Camacho Rosales M. Núñez-Velázquez Xiao Zhao Shoufeng Yang J. K. Sahu

Optical preforms and fibres manufacturing face numerous challenges with the demand for novel fibre designs with complex geometries using single or multiple materials. The multi-step approach currently followed to produce complex structures can endanger the mechanical integrity of the preform and add optical losses to the fibre. Often these complex and multi-step fabrication processes are time-consuming and yields are compromised. A novel fabrication process that has been gaining attractiveness in industries is the additive manufacturing (3D printing). Despite some progresses have been done with 3-D printing of glas, the work was demonstrated with a low melting temperature glass, such as soda lime, which was thermal fused before being extruded by a nozzle in heat building chamber [1]. An alternative approach, which has been used for 3-D printing glass is based in a feeding system of a quartz rod that is fused by a laser beam [2, 3].

10.1109/cleoe-eqec.2019.8871436

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Citations (10)

Effects of process parameters and geometry on dimensional accuracy and surface quality of thin strut heart valve frames manufactured by laser powder bed fusion

Research Square (Research Square) (2022)

Xiao Zhao Anqi Liang Matteo Bellin Neil W. Bressloff

Abstract Laser powder bed fusion (LPBF) is one of the most popular metal additive manufacturing technologies, which has found its applications in high-value sectors such as aerospace and biomedical devices. Some recent studies on the LPBF of stents have demonstrated its feasibility in the fabrication in thin strut structures including heart valve frames, as used in transcatheter aortic valve implantation (TAVI) for the treatment of severe aortic stenosis. The state of the art method of laser cutting TAVI frame limits the scope for novel concepts which are made possible by additive manufacturing. However, the surface quality and dimensional accuracy of LPBF parts are lower than that produced by laser cutting. To start the development of new TAVI concepts, the feasibility of manufacturing thin frames by LPBF has been investigated based the SAPIEN 3 frame by Edwards Lifesciences. In this study, simplified frames with strut size from 0.3 mm to 0.5 mm have been successfully manufactured. The effects of strut size, strut angle, laser power and scan speed on the dimensional accuracy and surface quality were systemically studied. In addition, a representative SAPIEN 3 frame was manufactured and assessed with high resolution X-ray scans. Good overall dimensional accuracy and low porosity was obtained for the SAPIEN 3 frame. However, inclined struts were found to have relatively low dimensional accuracy and poor surface quality.

10.21203/rs.3.rs-1271909/v1

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Fabrication and Characterization of AISI 420 Stainless Steel Using Selective Laser Melting

Materials and Manufacturing Processes (2015)

Xiao Zhao Qingsong Wei Bo Song Ying Liu Xi-Wang Luo

Selective laser melting (SLM) offers great possibilities to fabricate metal tools with a complex geometry, but there are limitations regarding some materials. This work focuses on the fabrication of AISI 420 stainless steel using SLM for the application of plastic injection mold. The melt characteristic of the powders was firstly concluded, and then the microstructure, phase composition, and hardness were characterized using scanning electron microscopy, X-ray diffraction, and Rockwell hardness test, respectively. The results showed that cellular microstructure was observed along the direction of the maximum heat flow. The proportion of the phases varies with the change of SLM processing parameters, which directly affects on the hardness of the parts. The relative density over 99% was obtained and the highest hardness presents 50.7 HRC, which meets the requirement of plastic injection molding application.

Selective Laser Melting

Rockwell scale

Metal injection molding

Molding (decorative)

Characterization

Relative density

10.1080/10426914.2015.1026351

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Citations (104)

Rapid fabrication of TiN/AISI 420 stainless steel composite by selective laser melting additive manufacturing

Journal of Materials Processing Technology (2019)

Xiao Zhao Q.S. Wei Nong Gao Enlai Zheng Yusheng Shi

Selective Laser Melting

Relative density

10.1016/j.jmatprotec.2019.01.028

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Citations (66)

Effect of Extrusion Size on Forming Process in Equal Channel Angular Pressing

Applied Mechanics and Materials (2013)

Xiao Zhao Ning Ning Zhao Na Chen

In order to meet the industrial demands for large-sized bulk ultrafine-grained materials, which were prepared by severe plastic deformation, the law curves of equivalent strain, equivalent stress and load of different-sized extrusions had been gotten by the finite element simulation of ECAP. The extrusion size has little effect on the values and distribution law of equivalent strain as well as the values of equivalent stress. With the increase of extrusion size, the distribution uniformity of equivalent stress decreases, and the extrusion load increases. Although the ECAP of the large-sized extrusions improve the requirements of mold and equipment, the chunk of evenly ultrafine-grained materials can be obtained by multiple passes.

Severe Plastic Deformation

10.4028/www.scientific.net/amm.275-277.2171

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Interfacial Characteristics of Austenitic 316l and Martensitic 15-5ph Stainless Steels Joined by Laser Powder Bed Fusion

SSRN Electronic Journal (2022)

Anqi Liang Sandeep Sahu Xiao Zhao Tomáš Polcar Andrew Hamilton

Laser powder bed fusion (LPBF) is an additive manufacturing (AM) technology capable of producing complex geometry components from a range of metals and alloys. The static mechanical strength of LPBF manufactured materials can rival that of the equivalent cast and wrought materials, but are more susceptible to fatigue failures due to stress concentrating roughness and porosity defects. The ability to process and join multiple powder materials within a single LPBF build process is an emerging capability that is now becoming commercially available. This new capability offers the possibility of compositional complexity, in addition to the geometric complexity offered by AM, and can help to eliminate the need for additional processing to join different materials. This study focuses on the combination of 316L austenitic stainless steel (SS) and precipitation hardening 15-5PH martensitic SS by LPBF. The interfacial characteristics and mechanical properties were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and microhardness testing. Good apparent bonding was observed at the interface without any visible cracks or defects. A finer-grain region was observed at a distance of 115 μm below the interface with a grain size of about half of that in the surrounding 15-5PH SS. A narrow compositional transition distance of 7 μm along the building direction (less than the 30 μm LPBF layer thickness) and a wavey-morphology interface with an amplitude of about 66 μm (about twice the LPBF layer thickness) were found. A sharp change of hardness was measured within ± 200 μm from the interface. Regions far from the interface exhibited similar microstructure and hardness as the corresponding single-material components. The results suggest that LPBF joining between 316L SS and 15-5PH SS can achieve each material's distinct microstructure and properties at far-interface regions, with a narrow wavey region (∼115 μm) at the interface that exhibits high densification and a sharp transition in microstructure and properties.

10.2139/ssrn.4257879

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Large-Scale Equipment and Higher Performance Materials for Laser Additive Manufacturing

Yusheng Shi Chunze Yan Qingsong Wei Zhang Lichao Shifeng Wen

The current available selective laser sintering (SLS) and selective laser melting (SLM) equipment has a relatively small effective building volume, which does not offer capability to integrally manufacture a larger dimension component.Therefore, our research team has investigated key SLS processing techniques such as the large powder bed preheating system and multi-laser scanning system, and then successfully developed of a series of large-scale SLS systems with the effective building volumes of 1400×700×500 mm 3 and 1400×1400×500 mm 3 , and SLM system with the effective building volume of 500×250×400 mm 3 .These large scale SLS/SLM systems will not only offer new capability to make large complex prototypes and products, but also provide higher volume production capability to make numerous small parts rapidly and cost-effectively.High performance materials have been developed for the large-scale SLS/SLM systems.Especially, nylon coated composite powders were prepared by a dissolutionprecipitation process, which is able to uniformly disperse the micro/nano-scale filler particles in the nylon matrix, and thus enhance the properties of nylon SLS parts.

Selective laser sintering

Selective Laser Melting

Integrally closed

10.3850/978-981-09-0446-3_022

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Citations (1)

Microstructure and Properties of a Low Carbon Steel after Equal Channel Angular Pressing

J. Wang Cheng Xu Y. Wang Z. Du Z. Zhang

Severe Plastic Deformation (SPD) processing, especially Equal-Channel Angular Pressing (ECAP) of steel and other iron-based alloys, has achieved increasing interest recently because of the potential for obtaining ultrafine grains and improving the properties [1–8]. Shin and co-workers [1–5] have conducted extensive investigations on ECAP processing of a 0.15 wt% C commercial carbon steel, usually at 623 K using route C. A near-equiaxed ultrafine grain structure of ∼0.2 µm resulted from 4 passes of ECAP [1] and this led to a substantial increase of the yield stress (YS) to ∼937 MPa and the ultimate tensile strength (UTS) to ∼943 MPa with reasonable elongations of ∼10 % [2,3]. Investigations by Fukuda et al. [8], conducted at room temperature using route Bc, achieved an essentially equiaxed microstructure with high grain boundary misorientations and an average grain size of ∼0.2 µm with a UTS of ∼800 MPa after ECAP through only three passes. These latter experiments used a carbon steel with a fairly low carbon content of 0.08 % C and there was an extensive region of strain hardening and a reasonably high elongation to failure in tensile testing at room temperature.

Carbon fibers

10.1002/3527602461.ch15g

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Citations (8)

Investigation and development of large-scale equipment and high performance materials for powder bed laser fusion additive manufacturing

Virtual and Physical Prototyping (2014)

Shifeng Wen Chunze Yan Q.S. Wei L.C. Zhang Xiao Zhao

The current available selective laser sintering (SLS) and selective laser melting (SLM) systems have relatively small effective building volumes, which do not offer capability to integrally manufacture a large dimension component. Therefore, our research team in Huazhong University of Science and Technology, China, has broken through some key techniques such as the large powder bed preheating system and multi-laser scanning technique, and then successfully developed a series of large-scale SLS systems with effective building volumes up to 1400×1400×500 mm3, and an SLM system with an effective building volume of 500×250×400 mm3. These large-scale SLS/SLM systems will not only offer new capability to make large complex prototypes and products, but also provide higher volume production capability to make numerous small parts rapidly and cost-effectively. In addition, several high performance materials have been developed for the large-scale SLS/SLM systems.

Selective Laser Melting

Selective laser sintering

Integrally closed

10.1080/17452759.2014.949406

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Citations (24)

Numerical Simulation of Large-Sized Pure Aluminum Rod under Multi-Pass ECAP

Advanced materials research (2013)

Xiao Zhao Ning Ning Zhao Na Chen

In order to obtain the bulk ultra-fine grain materials with excellent performance under the conditions of severe plastic deformation, the law curves of squeeze pressure, stress and strain of the extrusion process on large-sized pure aluminum rods had been gotten by the finite element simulation of 6-pass ECAP. With the increasing of extrusion passes, the maximum extrusion load increases significantly and the distribution uniformity on the values of equivalent stress and strain improves. So the multi-pass equal channel angular pressing can achieve good effect of grain refinement and improves the distribution uniformity of grain-size.

Rod

Severe Plastic Deformation

10.4028/www.scientific.net/amr.652-654.2019

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