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Enhancing fatigue life of as-printed martensitic M789 steel produced by laser powder bed fusion via in-process surface integrity improvement and phase change induced compressive residual stresses KU Leuven

Daniel Ordnung, Thibault Mertens, Mirko Sinico, Guichuan Li, Bey Vrancken, Brecht Van Hooreweder
The fatigue strength of metal components produced by Laser Powder Bed Fusion (LPBF) is often impaired by their limited surface quality, and surface finishing post-processing steps are typically required to improve the fatigue behavior. However, the complex geometries of LPBF parts sometimes inhibit conventional surface finishing. Recently, Incremental Dual Laser PBF (IDLPBF) was introduced as a strategy for in-process quality improvement of ...

In-situ alloying of NiTiNb ternary shape memory alloys via laser powder bed fusion using pre-alloyed NiTi and elemental Nb powders: Microstructure, phase transformation behavior and functional properties KU Leuven

Guichuan Li, Jan Van Humbeeck
Laser powder bed fusion (L-PBF) provides not only the advantage to make geometrically complex structures, but also the potential for in-situ alloying. In this work, (NiTi)100–xNbx (x = 1, 3, 5, 9 at%) ternary shape memory alloys were in-situ synthesized through L-PBF using a mixture of pre-alloyed near-equiatomic NiTi and elemental Nb powders. Low-Nb (1, 3 at%) alloys exhibit coarse columnar grains and high cracking tendency, while high-Nb (5, 9 ...

Processing of hydroxyapatite (HA)–Ti–6Al–4V composite powders via laser powder bed fusion (LPBF): effect of HA particle size and content on the microstructure and mechanical properties KU Leuven

Guichuan Li
This research study examines the influence of hydroxyapatite (HA) powder particle size and content on the processability, microstructure, and mechanical properties of the laser powder bed fusion (LPBF) fabricated Ti–6Al–4V (Ti64)-HA composites. For this purpose, various Ti64-HA composite powders were produced, and the effects of the HA particle size and content on the optical reflectance were investigated. Composite powders and the monolithic ...

Size effect on the microstructure, phase transformation behavior, and mechanical properties of NiTi shape memory alloys fabricated by laser powder bed fusion KU Leuven

Guichuan Li, Kim Vanmeensel, Jan Van Humbeeck
In this work, NiTi samples with different thicknesses (0.15–1.00 mm) were fabricated by laser powder bed fusion (LPBF) under variable scanning speeds (500–1200 mm s–1). The densification behavior, phase transformation behavior, and mechanical properties of the sample with different thicknesses are studied. The results indicate a strong size effect in the LPBF-fabricated NiTi alloy. The decrease of the sample thickness results in (i) the increase ...

Revealing the precipitation behavior of crack-free TiB2/Al-Zn-Mg-Cu composites manufactured by Laser Powder Bed Fusion KU Leuven

Guichuan Li, Seren Senol, Kim Vanmeensel
The microstructural evolution and precipitation behavior in additively manufactured age-hardenable TiB2/Al-Zn-Mg-Cu composites were investigated. As-built, direct-aged, solution-treated, and T6 heat-treated samples were characterized at macro, micro, and nano-scales to provide fundamental insights on the effect of the non-equilibrium L-PBF solidification microstructure and the presence of TiB2 reinforcement particles on the precipitation ...