Hongze Wang

• Doctor of Engineering
• Professor (Tenured-Associate) at Shanghai Jiao Tong University

At present, it is recognized that nanoparticles can improve the printability of many metals in fusion additive manufacturing, obtain finer microstructures and higher mechanical properties. However, it is unclear how nanoparticles affect the printing process and the extent of the effect. Numerical simulation can realize such a quantitative study. He...

Laser powder bed fusion (LPBF) technology has the potential to revolutionize the fabrication of complex metal components in the aerospace, medical, and automotive industries. However, keyhole pores may be induced during the rapid laser-metal interaction (∼10⁻⁵ s) of the LPBF. These inner porosities can potentially affect the mechanical properties o...

The accelerated growth of additive manufacturing (AM) technologies has greatly aided the expansion of the affiliated manufacturing industry, leading to cost savings in labor, materials, and time. However, manufacturing defects still limit the range of potential applications of AM components. Among the various surface treatments existing for AMed pa...

The fracture behaviour of artificial metamaterials often leads to catastrophic failures with limited resistance to crack propagation. In contrast, natural materials such as bones and ceramics possess microstructures that give rise to spatially controllable crack path and toughened material resistance to crack advances. This study presents an approa...

Additive manufacturing (AM) of dissimilar metals enables localized weight reduction, enhanced properties, and distinct performance requirements in components, leveraging the diverse physical properties of materials. However, elemental segregation and defects adversely impact properties. This study used in-situ X-ray imaging to monitor melt flow dur...

Keyhole instability during laser welding and laser powder bed fusion (LPBF) can cause keyhole collapse and pore formation. Using high-speed x-ray imaging, we demonstrate that the flow vortex–induced protrusion on the rear keyhole wall is crucial in initiating keyhole instability. Applying a transverse magnetic field suppresses the keyhole instabili...

Additive manufacturing (AM) processes are pivotal in various manufacturing industries due to their efficiency and ability to produce parts with complex structures and shapes. Metal powders, essential as feedstock for AM, especially in direct energy deposition (DED) and powder bed fusion (PBF) processes, have garnered significant attention from acad...

Ti-modified AlCuMg alloys have demonstrated great potential in improving the printability and mechanical properties of conventional Al alloys processed by laser powder-bed fusion (LPBF). However, an effective material design method, which considers processing parameters and solidification microstructure, is currently absent. Accordingly, the presen...

Blue laser spot welding electrical steel can improve material absorption, stabilise the molten pool and reduce heat input. The influence of process parameters on the welding quality of blue laser spot welding electrical steel is investigated. With the increase of laser power, a ‘single hump’ molten pool was generated. At the power of 1000 W, the me...

The surface quality of parts processed by laser additive manufacturing, especially laser-based directed energy deposition (LDED), makes it difficult to meet actual use requirements. In addition, defects generated during the long-term additive manufacturing process need to be removed in time. Therefore, laser additive and subtractive manufacturing i...

The mechanical responses and structure variations of Ta 80 Co 20 nanoscale metallic glass (MG) film samples upon cryogenic thermal cycling (CTC) treatment were studied. The simultaneous improvements of strength and deformation ability bring about a super-high strength of 4.5 GPa and a large plastic strain of about 80% after CTC treatment. The signi...

In this review, we propose a comprehensive overview of additive manufacturing (AM) technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field, of which many are inspired by nature itself. It describes how new AM technologies (e.g. continuous liquid interface production and multiphoton polym...

The Z-axis lifting height is significant in layer-by-layer fabrication using laser directed energy deposition (L-DED). In this paper, we have deeply examined the porosity and grain morphologies in the double layers of AlSi10Mg by blue laser directed energy deposition (BL-DED). After the deposition of a single track, the depositional head was raised...

Metal powders are essential for additive manufacturing (AM), with their morphology significantly impacting the performance of AM components. Gas atomisation (GA) is a common method for producing metal powders due to its efficiency and cost-effectiveness. However, GAed powders often exhibit defects such as alien powders, satellite powders, and hollo...

Laser powder bed fusion (L-PBF) is an innovative technique used to manufacture complex and customized parts. However, fabricating crack-sensitive Al–Cu–Mg alloy L-PBF parts with controlled defect levels remains challenging, as the effects of processing parameters on defect evolution are not well understood. In this study, we systematically investig...

This study presents next-generation biometric “metainterface𠇍 enabling programmable mechanical, thermal, and active interfacial effects for intelligent materials and systems with highly engineerable interfacial properties.

Large temperature gradient will produce high residual stress during laser powder bed fusion (LPBF). In metal matrix composites (MMCs), the thermal-induced stress distributes complexly. It is indispensable to study the interfacial stress of MMCs during LPBF process. In this study, a multi-phase finite element model was established to reveal the temp...

Numerical simulations using an Eulerian–Eulerian approach are performed to investigate the problem of a dense granular bed driven by a propagating shock wave with special emphasis on the particle-phase behavior. Validation of the granular model based on the kinetic theory of granular flow is performed by comparing the simulation results with experi...

The application of additive manufacturing (AM) technology plays a significant role in various fields, incorporating a wide range of cutting-edge technologies such as aerospace, medical treatment, electronic information, and materials. It is currently widely adopted for medical services, national defense, and industrial manufacturing. In recent year...

Joining Cu-Al with 0.6 mm is important for the high-power density battery in the new energy field. Low laser absorptivity is a challenge in Cu-Al welding with conventional infrared laser at around 1000 nm wavelength, where keyhole welding is necessary. It is difficult to control welding qualities in keyhole welding due to the intense flow and viole...

A hybrid laser composed of infrared and blue laser is applied in fabricating TiB2/AlSi7Mg composites on AlSi7Mg substrate by LPBF. The effect on formability, molten pool morphology, molten pool size and microstructure under infrared, blue and hybrid laser were compared. It was confirmed that hybrid laser can make up for the unbalanced energy distri...

High-reflectivity metals, e.g., copper and aluminum, have been widely applied for various industrial products such as power battery, electrical machinery, et al. However, owing to the low absorption rate of copper and aluminum to the conventional infrared laser (900-1080 nm), the keyhole welding mode is required, which is extremely unstable. A blue...

Additive manufacturing technology has greatly improved the design flexibility and accelerated the optimization verification of structure that cannot be easily and economically produced by traditional subtractive manufacturing processes. However, common defects such as surface roughness and porosity, affect the quality and reliability of the compone...

The dynamic loading behavior of materials plays a vital role in various engineering applications, such as aerospace protective components, armor, marine infrastructures, and automotive crash safety. The advent of additive manufacturing technologies has enabled the design of metamaterials that exhibit exceptional mechanical performance and artificia...

To obtain a better joint quality in butt welding of aluminum, the gap filling process and the quantifi-cation of the gap effects on the molten pool characteristic and the bubble formation were realized by a three-dimensional thermal-mechanistic-fluid coupled model, with the consideration of heat transfer, fluid flow, phase change and recoil pressur...

Gas atomization (GA) is the main method to produce metal powders for additive manufacturing (AM) because of its low cost and high efficiency. However, the liquid breakup behaviors in high-speed gas flow during GA remains unclear, especially the primary breakup in the near field and the secondary breakup in the far field. Great difficulty exists in...

Directed energy deposition (DED) of aluminum with infrared lasers faces many processing issues, e.g., poor formability, pore formation, high reflectivity, all lowering the productivity. In this paper, we developed and applied a 2 kW high-power (450 nm) blue laser directed energy deposition (BL-DED) of a nano-TiB2 decorated AlSi10Mg composite. The s...

A coaxial infrared-blue hybrid laser with low power infrared laser was used to clad high-reflectivity CuCrZr alloy on the AlSi7Mg substrate, and the formability and solidification behaviour in cladding with the high crack sensitivity materials under the infrared, blue and hybrid laser were compared. We demonstrated that the combination of a small p...

The existing mechanical metamaterials are often designed with periodic inter-connected structs with simple cylindrical or uniform hierarchical geometries, which relies on their parent materials to either have a good mechanical performance with low recoverability, or significantly sacrifices their mechanical performances to be highly recoverable. Bi...

There is an increasing demand of protective lightweight components in aerospace industries, and the high flexibility of additive manufacturing (AM) enables the design of complex structures to achieve such goal. In this study, a novel high-energy-absorption spherical hollow structure (SHS) was first engineered with a layer-wise failure mode and crys...

Aluminium alloys are difficult to be manufactured by directed energy deposition (DED) with the widely used infrared laser because of the low absorptivity. A blue laser with a 450 nm wavelength has a significantly higher laser absorptivity in processing aluminium. Here, we developed a 2000 W blue laser directed energy deposition (BL-DED) system for...

Additively manufactured (AMed) structure with superior strength is urgently required in Al alloy engineered products. Here, we reported a laser powder bed fusion (LPBF) AMed Al-Cu-Mg composite with excellent strength obtained by in-situ mixing TiB 2 and post-build heat treatment (PHT). The as-printed samples presented the bimodal structure with a r...

Welding has been widely used in industry for hundreds of years, and pursuing higher weld quality requires a better understanding of the welding process. The x-ray imaging technique is a powerful tool to in situ observe the inner characteristics of the melt pool in the welding process. Here, current progress in in situ x-ray imaging of the welding p...

In-situ pre-decorated different content of TiB2 particle reinforced 2024 Al matrix composites (xTiB2/2024Al composite, x = 0, 1, 2, 4, 6, 8 wt.%) were printed by laser powder bed fusion (LPBF). A quantitative equation was established to quantify heterogeneous nucleating potency by TiB2 nanoparticles on the grain size of the LPBFed samples. Optimize...

The non-castable Al alloy can hardly be printed by additive manufacturing (AM), because of the serious hot cracking problem induced by the wide solidification range. Here, the in-situ mixing salt method in combination with gas atomization, which is suitable for mass AM production, is first proposed to produce the powders of conventional non-castabl...

A coaxial infrared-blue hybrid laser system was adopted in the cladding of high reflectivity pure copper on an AlSi7Mg alloy substrate, and the cladding stability, molten pool size and microstructure of the cladded samples by three types of laser sources (infrared, blue and their hybrid sources) were compared. The infrared-blue hybrid laser was val...

To simultaneously enhancing the strength and ductility of novel heat-resistant Al–Fe–Ni alloy manufactured by selective laser melting (SLM), nano-TiB2 particles are introduced to break the strength-ductility trade-off. In this study, in-situ TiB2 decorated Al–Fe–Ni composite and Al–Fe–Ni base alloy have been successfully fabricated by SLM to invest...

The complex structure with large size (e.g., >500 mm) in aerospace, mould, nuclear power industry, has been urgently required for production with selective laser melting additive manufacturing (AM). Revealing the effect of the component size on the distortion could contribute to better understanding of AM and suggest control strategy for distortion...

Due to the high efficiency and low cost, gas atomization (GA) has been widely applied to produce metal powders. In this paper, the GA process is first modeled by combining the volume of fluid (VOF) model with dynamic adaptive mesh and the discrete phase model (DPM) to simulate the formation of the powders and the evolution of the defects. Simulatio...

Due to its high efficiency, cold metal transfer (CMT) arc additive manufacturing presents considerable potential in the aluminium alloy additive manufacturing industry. However, during CMT arc additive manufacturing, the surrounding air environment promotes the lateral flow of liquid aluminium and the instability of the molten pool, reduces the sur...

Laser manufacturing with high quality and efficiency is urgently required by the industry, while improving the absorption rate in the manufacturing process is the key method to reach the goal. In 2017, a 250W high power blue laser system with the wavelength around 250 nm was developed, which significantly improved the absorption rate in laser proce...

Laser powder deposition (LPD), as one of the most widely used additive manufacturing methods for metals, is an important rapid prototype manufacturing and repairing method for large components. However, great challenges exist in LPD of aluminum alloy due to the high reflectivity to laser, the poor fluidity of the powder, the high porosity in the pr...

Selective laser melting (SLM) of aluminium alloys is of research interest to produce customized or complex-shaped metal components for functional or structural applications. In order to palliate the undesirable residual stress developed in the SLM process, traditional post-annealing heat treatment has been widely used to lower residual stress in se...

Selective laser melting (SLM) technology is promising to fabricate complex-shaped metal components, especially light-weight aluminum (Al) alloy. Facing the grow requirement of thermal stability for applications in aviation and aerospace at high temperatures, the poor thermal stability of Al alloy needs to be improved. Thus, in this study, we develo...

During the additive manufacturing (AM) process, energy is transferred from the energy beam to the processed material. The high-energy input and uneven temperature distribution result in the high-temperature gradient, large thermal stress, and warping deformation. The scanning strategy, one of the representative AM processing parameters, plays an im...

Though selective laser melting (SLM) has a rapidly increasing market these years, the quality of the SLM-fabricated part is extremely dependent on the process parameters. However, the current metallographic examination method to find the parameter window is time-consuming and involves subjective assessments of the experimenters. Here, we proposed a...

In recent years, the motor has been increasingly used to replace the conventional gasoline engine for carbon emission reduction, and the high-performance motor is urgently required. The stator and rotor in a motor are made of hundreds of joined and laminated electrical steels. This paper covers the current research in joining the laminated electric...

A method of laser remelting with an ultra-thin additional element coating on the surface was put forward to improve both the hardenability of mild steel and the hardening efficiency. Both the 100% C and the 50% C-50% Cr (in mass) coatings were used. The additional surface coating increased the fusion efficiency of the laser irradiation because the...

Cold spray processing is a solid-state coating technique and an emerging method for additive manufacturing, in which metal powder particles are bonded through high-velocity impact-induced deformation. However, the severe plastic deformation of powder particles at extremely high strain rates, high strain gradients, and localized elevated temperature...

Featured Application This paper presents a laser ultrasonic testing (LUT) method for the inspection of internal hole defects in a Ti-6Al-4V part produced by additive manufacturing (AM). The LUT system achieved a resolution in sub-millimeter scale, demonstrating its significant potential in the quality evaluation of additive manufactured part. Abst...

It has been a long-standing challenge to obtain nanocrystalline pure aluminum with grain sizes below 10 nm by plastic deformation. Here, we studied the microstructure characteristics of two bonded pure aluminum powder particles after a cold spray process. In the particle–particle bonding region, nanometer-sized grains are revealed, about 30% of whi...

Metal additive manufacturing (AM) techniques, particularly laser powder-bed methods, have shown tremendous advantages for producing high-value, complex, and customized components. However, precisely controlling the microstructure and defects of the products in the AM process has been a long-standing issue. Here, we have developed a coupled thermal-...

The inner characteristics of solidification and crack propagation in laser spot welding of four representative aluminum alloys, A1050, A2024, A5083 and A6061, were firstly observed with the X-ray phase contrast method. Keyhole disappeared within 1 ms after the laser was shut down. The solidification process finished in 2 ms for A1050, 3 ms for A202...

Laser direct joining of metal and plastic plays a significant role in manufacturing of multiple material structures. To improve the strength of the joint, a controllable laser joining system was developed for polyethylene terephthalate (PET) plastic and titanium (Ti) based on the detected multiple signal sources. The main contribution of the articl...

The process of melting the metal and filling the gap in laser butt welding of aluminum was firstly in-situ observed with the X-ray phase contrast method. Because the molten metal dropped down through the gap firstly, keyhole and molten pool were initially observed in the middle of the samples, then grew up towards both the upper surface and the bot...

A 100 kW fiber laser was first used to weld steel. Speeds at the range between 0.3 and 5.0 m/min were tested, and the maximum weld bead depth of 70 mm was achieved by single pass welding. Solidification cracking and porosity occurred when the welding speed was lower than 0.5 m/min, while undercut appeared when the welding speed was higher than 3.0...

In this manuscript, weld pool dynamics in laser welding of various series of aluminum alloys were investigated by the in situ X-ray phase contrast imaging system. The experimental results showed that metal irradiated by laser was evaporated immediately, which generated the keyhole. Then metal surrounding the keyhole was melted gradually with the he...

The inner characteristics of solidification and crack propagation in laser spot welding of four representative aluminum alloys, A1050, A2024, A5083 and A6061, were firstly observed with the X-ray phase contrast method. Keyhole disappeared within 1 ms after the laser was shut down. The solidification process finished in 2 ms for A1050, 3 ms for A202...