Effect of laser rescanning on Ti6Al4V microstructure during selective laser melting

2020 ◽  
pp. 095440542097609
Author(s):  
Weipeng Duan ◽  
Meiping Wu ◽  
Jitai Han
Keyword(s):  
Wear Resistance ◽  
Titanium Alloy ◽  
Selective Laser Melting ◽  
Human Body ◽  
High Impact ◽  
Laser Melting ◽  
Heat Treated ◽  
Volume Porosity ◽  
Biomedical Field

TC4, which is one of the most widely used titanium alloy, is frequently used in biomedical field due to its biocompatible. In this work, selective laser melting (SLM) was used to manufacture TC4 parts and the printed parts were heat-treated using laser rescanning technology. The experimental results showed that laser rescanning had a high impact on the quality of SLMed part, and a different performance on wear resistance can be found on the basis. It can be seen that the volume porosity of the sample was 7.6 ± 0.5% without using any further processing technology. The volume porosity of the sample processed using laser rescanning strategy was decreased and the square-framed rescanning strategy had a relative optimal volume porosity (1.5 ± 0.3%) in all these five samples. With the further decreasing of volume porosity, the wear resistance decreased at the same time. As its excellent bio-tribological properties, the square-framed rescanning may be a potential suitable strategy to forming TC4 which used in human body.

scholarly journals The Effect of Building Direction on Microstructure and Microhardness during Selective Laser Melting of Ti6Al4V Titanium Alloy

2021 ◽  
Author(s):  
D. Palmeri ◽  
G. Buffa ◽  
G. Pollara ◽  
L. Fratini
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Titanium Alloy ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Ti6al4v Titanium Alloy ◽  
Mechanical Performances ◽  
Scanning Electron

AbstractDuring the last few years, additive manufacturing has been more and more extensively used in several industries, especially in the aerospace and medical device fields, to produce Ti6Al4V titanium alloy parts. During the Selective Laser Melting (SLM) process, the heterogeneity of finished product is strictly connected to the scan strategies and the building direction. An optimal managing of the latter parameters allows to better control and defines the final mechanical and metallurgical properties of parts. Acting on the building direction it is also possible to optimize the critical support structure. In particular, more support structures are needed for the sample at 0°, while very low support are required for the sample at 90°. To study the effects of build direction on microstructure heterogeneity evolution and mechanical performances of selective laser melted Ti6Al4V parts, two build direction samples (0°, 90°) were manufactured and analyzed using optical metallographic microscope (OM) and scanning electron microscopy (SEM). Isometric microstructure reconstruction and microhardness tests were carried out in order to analyze the specimens. The obtained results indicate that the build direction has to be considered a key geometrical parameter affecting the overall quality of the obtained products.

Assessment of Heat Treatment Effect on AlSi10Mg by Selective Laser Melting through Indentation Testing

2019 ◽  
Vol 813 ◽  
pp. 171-177 ◽  
Author(s):  
Giacomo Maculotti ◽  
Gianfranco Genta ◽  
Massimo Lorusso ◽  
Maurizio Galetto
Keyword(s):  
Selective Laser Melting ◽  
Melt Spinning ◽  
Ad Hoc ◽  
Indentation Test ◽  
Al Alloy ◽  
Laser Melting ◽  
Heat Treated ◽  
Processing Properties ◽  
Am Processes ◽  
Metal Additive

Selective Laser Melting (SLM) is one of the leader metal Additive Manufacturing (AM) processes thanks to its capability of coupling freeform design and environmental and economical sustainability to high mechanical properties. AlSi10Mg is a light weight Al-alloy with interesting processing properties and enhanced strength thanks to the presence of Mg, which, hence, finds application in several industrial fields. Furthermore, SLM allows overcoming those design constraints set by casting and melt spinning; however, SLM AlSi10Mg components require to be heat treated, both to strengthen the material and to engineer the microstructure. In this work, in order to assess the effectiveness of heat treatments on AlSi10Mg by SLM, an ad hoc analysis procedure based on statistical tools is applied in combination with indentation characterisation tests. In particular, to achieve full scale characterisation, traditional Brinell hardness and Instrumented Indentation Test (IIT) in macro and nano-range are considered. In particular, IIT is applied both at the lower end of macro range to provide consistency and statistically investigate relationship with Brinell scale and in the nano-range, enabling local, i.e. grain, and surface properties to be characterised.

Liquation and Crystallization Cracks in Aluminum Alloy AA2024 during Selective Laser Melting

2021 ◽  
Vol 410 ◽  
pp. 203-208
Author(s):  
I.S. Loginova ◽  
N.A. Popov ◽  
A.N. Solonin
Keyword(s):  
Aluminum Alloy ◽  
Selective Laser Melting ◽  
Laser Scanning ◽  
Scanning Speed ◽  
Melting Zone ◽  
Alloying Elements ◽  
Laser Melting ◽  
Laser Scanning Speed ◽  
Positive Effect

In this work we studied the microstructure and microhardness of standard AA2024 alloy and AA2024 alloy with the addition of 1.5% Y after pulsed laser melting (PLM) and selective laser melting (SLM). The SLM process was carried out with a 300 W power and 0.1 m/s laser scanning speed. A dispersed microstructure without the formation of crystallization cracks and low liquation of alloying elements was obtained in Y-modified AA2024 aluminum alloy. Eutectic Al3Y and Al8Cu4Y phases were detected in Y-modified AA2024 aluminum alloy. It is led to a decrease in the formation of crystallization cracks The uniform distribution of alloying elements in the yttrium-modified alloy had a positive effect on the quality of the laser melting zone (LMZ) and microhardness.

Martensite decomposition during post-heat treatments and the aging response of near-α Ti–6Al–2Sn–4Zr–2Mo (Ti-6242) titanium alloy processed by selective laser melting (SLM)

2021 ◽  
pp. 2050018
Author(s):  
Haiyang Fan ◽  
Yahui Liu ◽  
Shoufeng Yang
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Titanium Alloys ◽  
Selective Laser Melting ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Aging Treatment ◽  
Water Quenching ◽  
Laser Melting ◽  
Aging Response

Ti–6Al–2Sn–4Zr–2Mo (Ti-6242), a near-[Formula: see text] titanium alloy explicitly designed for high-temperature applications, consists of a martensitic structure after selective laser melting (SLM). However, martensite is thermally unstable and thus adverse to the long-term service at high temperatures. Hence, understanding martensite decomposition is a high priority for seeking post-heat treatment for SLMed Ti-6242. Besides, compared to the room-temperature titanium alloys like Ti–6Al–4V, aging treatment is indispensable to high-temperature near-[Formula: see text] titanium alloys so that their microstructures and mechanical properties are pre-stabilized before working at elevated temperatures. Therefore, the aging response of the material is another concern of this study. To elaborate the two concerns, SLMed Ti-6242 was first isothermally annealed at 650[Formula: see text]C and then water-quenched to room temperature, followed by standard aging at 595[Formula: see text]C. The microstructure analysis revealed a temperature-dependent martensite decomposition, which proceeded sluggishly at [Formula: see text]C despite a long duration but rapidly transformed into lamellar [Formula: see text] above the martensite transition zone (770[Formula: see text]C). As heating to [Formula: see text]C), it produced a coarse microstructure containing new martensites formed in water quenching. The subsequent mechanical testing indicated that SLM-built Ti-6242 is excellent in terms of both room- and high-temperature tensile properties, with around 1400 MPa (UTS)[Formula: see text]5% elongation and 1150 MPa (UTS)[Formula: see text]10% elongation, respectively. However, the combination of water quenching and aging embrittled the as-built material severely.

Mechanical Behaviour of Gas Nitrided Ti6Al4V Bars Produced by Selective Laser Melting

2016 ◽  
Vol 704 ◽  
pp. 225-234 ◽  
Author(s):  
Peter Franz ◽  
Aamir Mukhtar ◽  
Warwick Downing ◽  
Graeme Smith ◽  
Ben Jackson
Keyword(s):  
Heat Treatment ◽  
Selective Laser Melting ◽  
Nitrided Layer ◽  
Xrd Analysis ◽  
Compound Layer ◽  
Processing Parameters ◽  
Heat Treatments ◽  
Laser Melting ◽  
Gas Nitriding ◽  
Heat Treated

Gas atomized Ti-6Al-4V (Ti64) alloy powder was used to prepare distinct designed geometries with different properties by selective laser melting (SLM). Several heat treatments were investigated to find suitable processing parameters to strengthen (specially to harden) these parts for different applications. The results showed significant differences between tabulated results for heat treated billet Ti64 and SLM produced Ti64 parts, while certain mechanical properties of SLM Ti64 parts could be improved by different heat treatments using different processing parameters. Most heat treatments performed followed the trends of a reduction in tensile strength while improving ductility compared with untreated SLM Ti64 parts.Gas nitriding [GN] (diffusion-based thermo-chemical treatment) has been combined with a selected heat treatment for interstitial hardening. Heat treatment was performed below β-transus temperature using minimum flow of nitrogen gas with a controlled low pressure. The surface of the SLM produced Ti64 parts after gas nitriding showed TiN and Ti2N phases (“compound layer”, XRD analysis) and α (N) – Ti diffusion zones as well as high values of micro-hardness as compared to untreated SLM produced Ti64 parts. The microhardness profiles on cross section of the gas nitrided SLM produced samples gave information about the i) microhardness behaviour of the material, and ii) thickness of the nitrided layer, which was investigated using energy dispersive spectroscopy (EDS) and x-ray elemental analysis. Tensile properties of the gas nitrided Ti64 bars produced by SLM under different conditions were also reported.

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