Influence of laser post-processing on pore evolution of Ti–6Al–4V alloy by laser powder bed fusion

Shen, Bingnan; Li, Hui; Liu, Sheng; Zou, Jing; Shen, Shengnan; Wang, Yinghe; Zhang, Tao; Zhang, Dongqi; Chen, Yinghua; Qi, Haiqin

doi:10.1016/j.jallcom.2019.152845

Cited by 41 publications

(23 citation statements)

References 33 publications

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“…To simplify the numerical calculations, several assumptions were proposed as follows: The laser beam is regarded as a continuous Gaussian heat source due to the short pulse separation pass of the laser (pulsed Nd: YAG laser) [ 27 ]. The deformation of mechanical behavior has negligible effect on fluid field [ 27 ]. The laser absorptivity of the material is assumed to be constant [ 27 ].…”

Section: Mathematical Modelingmentioning

confidence: 99%

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In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Zhou

Han

et al. 2021

Materials

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Laser polishing is a widely used technology to improve the surface quality of the products. However, the investigation on the physical mechanism is still lacking. In this paper, the established numerical transient model reveals the rough surface evolution mechanism during laser polishing. Mass transfer driven by Marangoni force, surface tension and gravity appears in the laser-induced molten pool so that the polished surface topography tends to be smoother. The AlSi10Mg samples fabricated by laser-based powder bed fusion were polished at different laser hatching spaces, passes and directions to gain insight into the variation of the surface morphologies, roughness and microhardness in this paper. The experimental results show that after laser polishing, the surface roughness of Ra and Sa of the upper surface can be reduced from 12.5 μm to 3.7 μm and from to 29.3 μm to 8.4 μm, respectively, due to sufficient wetting in the molten pool. The microhardness of the upper surface can be elevated from 112.3 HV to 176.9 HV under the combined influence of the grain refinement, elements distribution change and surface defects elimination. Better surface quality can be gained by decreasing the hatching space, increasing polishing pass or choosing apposite laser direction.

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Section: Mathematical Modelingmentioning

confidence: 99%

“… The deformation of mechanical behavior has negligible effect on fluid field [ 27 ]. The laser absorptivity of the material is assumed to be constant [ 27 ]. The flow field in the molten pool is assumed as an incompressible Newtonian laminar flow [ 27 ].…”

Section: Mathematical Modelingmentioning

confidence: 99%

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Zhou

Han

et al. 2021

Materials

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“…Note that the AM process used a laser beam to manufacture the part in a layer-by-layer style. During AM process, issues including balling and porosity can be formed due to the high-power density [2] and occur in the inner surface of four holes. Next, the sample was cut by using wire-cutting equipment (FH-020C, Suzhou Xingjie CNC Technology Co., Ltd., Suzhou, China).…”

Section: Of 12mentioning

confidence: 99%

“…The most common material discontinuities are voids and pores situated in the bulk of the fused material. Such defects seriously affect the mechanical properties of the workpiece, limiting the development and application of the AM process [2]. Therefore, there is an urgent need for non-destructive quality evaluation technology for the process control of AM.…”

mentioning

confidence: 99%

Detection of Internal Holes in Additive Manufactured Ti-6Al-4V Part Using Laser Ultrasonic Testing

Zhang

et al. 2020

Applied Sciences

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For a non-contact, non-destructive quality evaluation, laser ultrasonic testing (LUT) has received increasing attention in complex manufacturing processes, such as additive manufacturing (AM). This work assessed the LUT method for the inspection of internal hole defects in additive manufactured Ti-6Al-4V part. A Q-switched pulsed laser was utilized to generate ultrasound waves on the top surface of a Ti-6Al-4V alloy part, and a laser Doppler vibrometer (LDV) was utilized to detect the ultrasound waves. Sub-millimeter (0.8 mm diameter) internal hole defect was successfully detected by using the established LUT system in pulse-echo mode. The method achieved a relatively high resolution, suggesting significant application prospects in the non-destructive evaluation of AM part. The relationship between the diameter of the hole defects and the amplitude of the laser-generated Rayleigh waves was studied. X-ray computed tomography (XCT) was conducted to validate the results obtained from the LUT system.

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“…The results showed that the LED has an important influence on the surface morphology of the forming part, with a higher LED possibly producing a balling effect, and a lower LED tending to produce defects, such as porosity and microcracks, subsequently affecting the surface roughness and porosity of the parts. Yakout et al and Shen et al used a LED formula, as follows [12,13]:…”

Section: Introductionmentioning

confidence: 99%

Investigation of Laser Polishing of Four Selective Laser Melting Alloy Samples

Zhang

et al. 2020

Applied Sciences

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Selective laser melting (SLM) is a layer by layer process of melting and solidifying of metal powders. The surface quality of the previous layer directly affects the uniformity of the next layer. If the surface roughness value of the previous layer is large, there is the possibility of not being able to complete the layering process such that the entire process has to be abandoned. At least, it may result in long term durability problem and the inhomogeneity, may even make the processed structure not be able to be predicted. In the present study, the ability of a fiber laser to in-situ polish the rough surfaces of four typical additive-manufactured alloys, namely, Ti6Al4V, AlSi10Mg, 316L and IN718 was demonstrated. The results revealed that the surface roughness of the as-received alloys could be reduced to about 3 μm through the application of the laser-polishing process, and the initial surfaces had roughness values of 8.80–16.64 μm. Meanwhile, for a given energy density, a higher laser power produced a laser-polishing effect that was often more obvious, with the surface roughness decreasing with an increase in the laser power. Further, the polishing strategy will be optimized by simulation in our following study.

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Influence of laser post-processing on pore evolution of Ti–6Al–4V alloy by laser powder bed fusion

Cited by 41 publications

References 33 publications

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Detection of Internal Holes in Additive Manufactured Ti-6Al-4V Part Using Laser Ultrasonic Testing

Investigation of Laser Polishing of Four Selective Laser Melting Alloy Samples

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