Combination of Scanning Strategies and Optimization Experiments for Laser Beam Powder Bed Fusion of Ti-6Al-4V Titanium Alloys

Abstract

This paper studies the effects of different combinations of scanning strategies between layers on the surface quality, tensile properties, and microstructure of samples in a laser beam powder bed fusion (L-PBF) formation experiment of Ti-6Al-4V titanium alloy. The purpose of this experiment was to improve the comprehensive performance of the piece by selecting the optimal combination of scanning strategies. The results show that the surface roughness of the L-PBF specimen was the lowest under the combination of the CHESS scanning strategy, reaching 14 μm. The surface hardness of the samples was generally higher with the LINE scanning strategy and the angle offset of 90°, reaching 409 HV. The overall density of the samples was higher under the combination of CHESS scanning strategies, reaching 99.88%. Among them, the CHESS&45° sample had the best comprehensive properties, with a density of 99.85%, a tensile strength of up to 1125 MPa, a yield strength of 912 MPa, and an elongation of 8.2%. The fractured form was a ductile fracture, with many dimple structures. Compared with the CHESS scanning strategy, the tensile properties of the CHESS&45° samples were improved by 12.8%. The microstructure of the L-PBF sample was mainly composed of the primary β phase and α’ martensite phase. The upper surface of the CHESS scanning strategy combination sample had a clear melt channel, and the distribution of each phase was uniform. A certain number of columnar β crystals were distributed in the longitudinal section of the sample, which was paralleled to the build direction. The columnar β crystals of CHESS&45° were relatively coarse, which enhanced the tensile properties of the sample.

Influence of Density Gradient on the Compression of Functionally Graded BCC Lattice Structure

“…The particle size of TC4 titanium alloy powder is 15–53 µm (tested by Laser particle size analyzer, Cilas 990 DL; CILAS, Orleans, France), and its morphology and chemical composition are shown in Figure 2 and Table 1 , respectively. According to the preliminary study of the SLM forming process parameters [ 32 , 33 , 34 ], the forming parameters were 230 W laser power, 100 μs exposure time, 50 μm point distance, 100 μm hatch spacing, and 50 μm layer thickness. After the specimens were formed, the fabricated lattice structures were separated from the platform plate of the SLM machine by an EDM (electrical discharge machining) wire-cutting process on a CMNE machine (Beijing, China), and no heat treatment was applied to the sample.…”

Effect of Surface Textures and Fabrication Methods on Shear Bond Strength Between Titanium Framework and Auto-Polymerizing Acrylic Repair Resin

“…The development of CAD and digital fabrication techniques has allowed the production of more accurate and homogeneous Ti prostheses in a shorter time [6,12,24]. Digital fabrication methods could be subtractive or additive techniques.…”

Experimental Research on Variable Parameter Forming Process for Forming Specimen of TC4 Titanium Alloy by Selective Laser Melting

“…Laser power and experimental parameters are shown in Table 2. The experimental data of specimens 1-8# were referred to by Shi W et al [24]. For specimens 9-20#, as seen in the above experimental data, the laser power was selected at 250 W-300 W. Additionally, the specimens were divided into six hierarchies (the hierarchy refers to the number of layers divided and aggregate thickness refers to the thickness of the hierarchy), from the first hierarchy to the sixth hierarchy, and corresponding experiments were conducted on each different hierarchy.…”