Qingbo Jia

Soochow University | SUDA

Hollow-strut metal lattice structures are currently attracting extensive attention due to their excellent mechanical performance. Inspired by the node structure of bamboo, this study aimed to investigate the mechanical performance of the gradient hollow-strut octet lattice structure fabricated by laser powder bed fusion (LPBF). The effect of geomet...

This study presented a comprehensive investigation into the microstructures, strengthening mechanisms and deformation behaviours of a novel N-doped Co-28Cr-6Mo (CCMN) alloy fabricated by laser powder bed fusion (LPBF). In addition to the well-known cellular structures, lattice defects including dislocations and stacking faults (SFs), the near-spher...

The introduction of Sc/Zr inoculates to aluminium (Al) alloys for laser powder bed fusion (LPBF) provides numerous benefits, including laser processability improvement, solidification microstructure control and mechanical property enhancement. Though great efforts have been put into tailoring the microstructure and room temperature mechanical prope...

High−temperature wear failure has been a major challenge to die parts. This work provides a comprehensive study on the high−temperature wear performance of a TiC/H13 composite coating prepared by laser metal deposition (LMD). The microstructures of wrought H13 samples, LMD−processed H13 and TiC/H13 samples were systematically investigated. The refi...

The laser absorbents are necessary in the process of laser transmission welding (LTW) transparent thermoplastics. It has been demonstrated that metal absorbents in LTW have great advantages for achieving a high quality joint, though the decomposition of thermoplastics is difficult to control. Metal particle absorbents with different melting point,...

The processability of laser powder bed fusion (LPBF) fabricated Al alloys can be significantly improved by the introduction of grain refinement inoculates. However, tensile testing results showed that the fabricated alloys exhibited unusual deformation characteristics, including discontinuous yielding, Lüders elongation and low work hardening behav...

The widespread application of selective laser melting (SLM) fabricated high performance lightweight Al components is hindered by the available commercial alloys due to their limited mechanical properties and processability. The introduction of Sc/Zr elements to the Al matrix for SLM provides conspicuous benefits, including grain refinement, precipi...

The dynamic metallurgical characteristics of the selective laser melting (SLM) process offer fabricated materials with non-equilibrium microstructures compared to their cast and wrought counterparts. To date, few studies on the precipitation kinetics of SLM processed heat-treatable alloys have been reported, despite the importance of obtaining such...

Quenching experiments having different cooling rates up to 16000 ˚C/s were applied on rolled Ti-6Al-4V sheets. Twins were not observed in the condition with a low cooling rate. With an increased quenching rate to above 10000 ˚C/s, {10-11} twins were formed in the temperature range of 550 - 850 ˚C, and {10-12} twins were activated at an even lower t...

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...

Additive manufacturing, or 3D printing, has brought tremendous opportunities for the design and making of metallic components with high geometrical complexity. However, in order to maximize the performance and functionality of a specific part, the additive manufacturing industry currently still faces fundamental issues of material processability an...

Static coarsening mechanism of selective laser melted (SLMed) Ti–6Al–4V with a lamellar microstructure was established at temperatures from 700 °C to 950 °C. Microstructure evolution revealed that high heat treatment temperature facilitated martensite decomposition and promoted lamellae growth. At each temperature, the growth rate decreased with in...

Selective Laser Melting (SLM) has received tremendous attentions due to its high degree of flexibility for the design and fabrication of geometrically complex parts. However, the majority of the currently applied metals for this advanced technology are still based on the traditional weldable and/or castable alloys, and the resulting mechanical prop...

AlScZr and AlErZr alloys with Sc or Er additions of ~0.6 at.% were prepared by a novel wedge mould casting and laser remelting methodology. Precipitation strengthening and thermal stability were studied using hardness testing and transmission electron microscopy. After ageing, the AlScZr alloy achieved a peak hardness of 113 HV0.5 and possessed pro...

The as-Selective Laser Melted (as-SLMed) Ti-6Al-4V generally has a martensitic microstructure. In the present study, martensite decomposition was investigated in various annealed samples by XRD, SEM and TEM. It has been found that annealing at 700 °C or 800 °C for 2 h was not sufficient to obtain a fully decomposed microstructure. The amount of mar...

To improve the selective laser melting (SLM) productivity, a high laser power and accordingly adjusted parameters are employed to facilitate a high build rate. Three distinct processing strategies with incremental build rate are developed for SLM Ti-6Al-4V. Various types of defects are investigated. Further studies were carried out by heat-treatmen...

The laser metal deposition (LMD) additive manufacturing process was applied to produce TiC/Inconel 625 composite parts. The high-temperature oxidation performance of the LMD-processed parts and the underlying physical/chemical mechanisms were systematically studied. The incorporation of the TiC reinforcement in the Inconel 625 improved the oxidatio...

This work presented a comprehensive study of high-temperature oxidation behaviors and mechanisms of Selective laser melting (SLM) processed Inconel 718 superalloy parts using different methods including isothermal oxidation testing, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The experimental results re...

Selective laser melting (SLM) process was used to prepare the nanocrystalline titanium carbide (TiC)-reinforced Inconel 718 matrix bulk-form nanocomposites in the present study. An in-depth relationship between SLM process, microstructures, properties, and metallurgical mechanisms was established. The insufficient laser energy density (eta) input l...

The bulk-form in situ WC-based cermets were prepared by selective laser melting of W–C–Ni ternary powder system. The in situ formed WC crystals generally had a unique triangular microstructure which was developed via a layer-by-layer growth mechanism by the multilayered stacking of (0001) basal planes of WC. An increase in the applied laser energy...

This paper presented a comprehensive study of densification behavior, microstructural features, microhardness, wear performance and high-temperature oxidation properties of Inconel 718 parts fabricated by selective laser melting (SLM), a typical additive manufacturing process. The relationship of processing conditions, microstructures and material...

Laser metal deposition (LMD) additive manufacturing of TiC particle reinforced Inconel 718 composite parts was performed. The influence of laser energy density (LED) on densification, microstructures and wear behaviour of LMD-processed composites was studied. It showed that using a LED of 280 J mm-3 produced ̃5% porosity in LMD-processed composites...