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Introduction
Additional affiliations
June 2017 - present
Education
February 2014 - August 2017
September 2009 - December 2013
Publications
Publications (39)
Surface quality represents a critical challenge in additive manufacturing (AM), with surface roughness serving as a key parameter that influences this aspect. In the aerospace industry, the surface roughness of the aviation components is a very important parameter. In this study, a typical Al alloy, AlSi10Mg, was selected to study its surface rough...
Yang Jixin R Wang X Q Hu- [...]
Y J Bi
Laser directed energy deposition (LDED) process has unique advantage in rapid forming of large-sized metal components, gradient material/structural components, or repairing/remanufacturing worn parts. However, the high residual stress and strong anisotropy in mechanical properties of the as-deposit components limit the application of LDED technolog...
Chromium nitride powder is blended with pre-alloyed powder to make an overmatched powder with a high nitrogen concentration in order to manufacture high-nitrogen steel by selective laser melting. By employing a wider range of process parameters, the impact of process parameters on the relative density, nitrogen concentration, microstructure, and me...
In-situ synthesis of ceramics hybrid reinforced Al matrix composites (AMCs) by laser powder bed fusion (L-PBF) induced combustion reaction is a promising strategy to strengthen Al alloys. However, the in-situ formed microstructures are highly sensitive to the stability of mixed multi-powder feedstocks, which is a challenge to fabricate AMCs. This w...
High-nitrogen stainless steels are widely used due to their excellent comprehensive performance. In this study, the effects of process parameters (laser power, scanning speed, and cavity pressure) on the formation of high-nitrogen stainless steels were studied by using conventional selective laser melting and high-pressure selective laser melting (...
Direct aging treatment is an important post-processing procedure, yet little research has been done on how it balances the mechanical properties and the stress removal for selective laser melted (SLMed) AlSi10Mg alloys. Here, we proposed a typical direct aging treatment on SLMed AlSi10Mg alloys, and studied the effects on their microstructure, prop...
This work investigated the influence of microstructure anisotropy on fracture toughness of SLM fabricated and directly aged 15‐5 PH stainless steel. A bi‐modal columnar (within the melt pool) and equiaxed (at the melt pool boundary) microstructure formed on the vertical plane, which resulted in a higher yield strength in the horizontal direction th...
This work investigates the effects of various processing parameters (laser power, scanning speed, hatch distance and beam offset) on the resultant inclined up-facing surface roughness of AlSi10Mg alloys produced by laser powder bed fusion (LPBF). A two-step approach, orthogonal test followed by the Doehlert matrix design (DMD) test is used to effic...
With the upgrade of additive manufacturing (AM) equipment, pure copper and various Cu-based alloys with almost full density have been successfully produced, maintaining their excellent thermal and electrical conductivity and good mechanical properties at high temperatures as well. In this paper, a model with a series of inclined surface structures...
Laser cladding is widely used for feature repair and manufacturing of large structural components. However, due to processing parameters and thus energy densities variation, defects can form in laser clad materials. There is a need to understand the relationship between energy densities and cladding quality. This study therefore investigates the cr...
This study demonstrates a novel design of a three-dimensional structural hood to remove the vapor and spatter generated during the Direct energy deposition (DED) process. The hood is composed of three planes, including an inlet block, an outlet block and a shell, with three splitter structures in each block. Computational fluid dynamics (CFD) simul...
The preparation of aluminum matrix composites (AMCs) by laser additive manufacturing (AM) technology has become an important means of improving performance of aluminum alloys. In this work, a novel in-situ synthesis method of selective laser melting combined combustion synthesis (SLM-CS) was used to prepare dual-phase reinforced AMCs. The feasibili...
A survey of fatigue data for Ti-6Al-4V is presented, a collation of several hundred data points. When tested in fully reversed loading, wrought and additively manufactured (AM) materials show similar behaviours until ~105 cycles, after which the AM specimens show noticeably poorer fatigue strengths than wrought materials. Under high cycle condition...
The hemming process is one of the most commonly used forming processes for aluminium alloys in the automotive industry and requires bending the aluminium alloy sheet to 180° without generating cracks or surface cosmetic defects. However, existing commercial Al-Mg-Si alloys (AA6xxx aluminium alloys) used in the automotive industry could easily fail...
A martensitic stainless steel AISI420 fabricated by selective laser melting (SLM) and post-processed by austenitizing and tempering heat treatment was investigated in this study. The as-fabricated SLMed AISI420 showed a strong mechanical property anisotropy and low ductility in the longitudinal direction. Detailed microstructural characterization r...
Large columnar grains with strong texture in direct laser deposited (DLDed) Ti-6Al-4V (Ti-64) is widely reported to cause issues like strong mechanical property anisotropy and poor tensile strength, which make this material unsuitable for many uses in the aerospace industry. In this study, a microstructure refinement investigation was carried out b...
A series of complex post-build heat treatment procedures are usually inevitable for selective laser melted (SLMed) Al-Si-Mg alloys, aiming to remove significant process-induced residual strains. In this work, we propose a new method to avoid the post-build heat treatment without compromising the mechanical properties in SLMed Al alloy A357. By heat...
The relationship between defects and mechanical properties, especially fatigue properties, of selective laser melted (SLMed) Al-7Si-0.6Mg alloy built with different processing parameters has been investigated. With relatively high densities, although the tensile strength is not affected, ductility and fatigue properties vitally vary with different...
The heat treatment of a component made of an Al-Si-Mg alloy by an SLM process comprises subjecting the component to a stress relieving heat treatment, without sintering loose powder entrapped with or within the component, prior to cutting the component from a build platform on which the component was made by the SLM process. The stress relieved com...
Additive Manufacturing for the Aerospace Industry explores the design, processing, metallurgy and applications of additive manufacturing (AM) within the aerospace industry. The book's editors have assembled an international team of experts who discuss recent developments and the future prospects of additive manufacturing. The work includes a review...
The ageing responses of selective laser melted Al-7Si-0.6Mg alloy with different solid solution treatment times are investigated in this work. Silicon particles with random crystallographic orientations are the dominant precipitates at the direct aged condition. With 1 or 8 h solid solution treatment, the precipitation sequence resembles that of ca...
Defects in Al-7Si-Mg and Al-10Si-Mg alloys produced by selective laser melting are categorised into three types. The first type are large irregular-shaped defects with unmelted powder particles, formed due to a lack of fusion as a result of insufficient volumetric energy density. The second type are small round gas pores below 5 µm in diameter, ass...
Although as one of the most important industrial alloys with a high strength/density ratio and good thermal properties, aluminium alloy A357 has been seldom studied in the selective laser melting (SLM) field. Also, since conventional casting and SLM are two different techniques, it is not known whether SLM procedures and parameters for heat treated...
In this work the tensile behaviour of selective laser melted (SLMed) aluminium alloy A357 in the as-fabricated and heat-treated states is explained using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and transmission electron backscatter diffraction (t-EBSD). The as-built sample...