Multi-scale simulation of the dendrite growth during selective laser melting of rare earth magnesium alloy

2021 ◽  
Vol 30 (1) ◽  
pp. 015005
Author(s):  
Wenli Wang ◽  
Wenqiang Liu ◽  
Xin Yang ◽  
Rongrong Xu ◽  
Qiuyun Dai
Keyword(s):  
Selective Laser Melting ◽  
Interpolation Method ◽  
Primary Dendrite ◽  
Concentration Field ◽  
Dendrite Growth ◽  
Scale Model ◽  
Laser Melting ◽  
Dendrite Morphology ◽  
Multi Scale ◽  
Primary Dendrite Arm Spacing

Abstract The solidification microstructure of the alloy fabricated by the selective-laser-melting (SLM) process can significantly impact its mechanical properties. In this study, a multi-scale model which couples the macroscale model for thermal-fluid and microscale cellular automata (CA) was proposed to simulate the complex solidification evolution and the dendrite growth (from planar to cellular to dendritic growth) during the SLM process. The solid–liquid interface of CA was dispersed with the bilinear interpolation method. On that basis, the curvature was accurately determined, and the calculation result was well verified by employing the Kurz–Giovanola–Trivedi analytical solution. The dendrite morphology, solute distribution, and primary dendrite arm spacing during the solidification of the SLM molten pool were quantitatively analyzed with the proposed model, well consistent with the experiment. The distribution of the undercooling field and the concentration field at the tip of dendrites different orientations were analyzed, and the two competing growth mechanisms of converging and diverging growth were revealed. Moreover, the research also indicates that during the growth of dendrites, the result of dendrite competition is determined by the height of the dendrite tip position in the direction of the thermal gradient, while the distribution of the concentration field (symmetrical or asymmetric) at the tip of the dendrite critically impacted the competing growth form of dendrites.

scholarly journals 316L Stainless Steel Manufactured by Selective Laser Melting and Its Biocompatibility with or without Hydroxyapatite Coating

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 548 ◽  
Author(s):  
Jiapeng Luo ◽  
Xiao Jia ◽  
Ruinan Gu ◽  
Peng Zhou ◽  
Yongjiang Huang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Selective Laser Melting ◽  
316L Stainless Steel ◽  
Primary Dendrite ◽  
Sol Gel ◽  
Scanning Speed ◽  
Steel Matrix ◽  
Laser Melting ◽  
Relative Growth

To fabricate metallic 316L/HA (hydroxyapatite) materials which meet the requirements of an implant’s mechanical properties and bioactivity for its function as human bone replacement, selective laser melting (SLM) has been employed in this study to prepare a 316L stainless steel matrix, which was subsequently covered with a hydroxyapatite (HA) coating using the sol-gel method. High density (98.9%) as-printed parts were prepared using a laser power of 230 W and a scanning speed of 800 mm/s. Austenite and residual acicular ferrite existed in the microstructure of the as-printed 316L stainless steel, and the sub-grain was uniform, whose primary dendrite spacing was around 0.35 μm. The as-printed 316L stainless steel showed the highest Vickers hardness, elastic modulus, and tensile strength at ~ (~ means about; same applies below unless stated otherwise) 247 HV, ~214.2 GPa, and ~730 MPa, respectively. The elongation corresponding to the highest tensile strength was ~38.8%. The 316L/HA structure, measured by the Relative Growth Rate (RGR) value, exhibited no cell cytotoxicity, and presented better biocompatibility than the uncoated as-printed and as-cast 316L samples.

scholarly journals Multi-scale microstructure high-strength titanium alloy lattice structure manufactured via selective laser melting

RSC Advances ◽  
2021 ◽  
Vol 11 (37) ◽  
pp. 22734-22743
Author(s):  
Xin Yang ◽  
Wenjun Ma ◽  
Wenping Gu ◽  
Zhaoyang Zhang ◽  
Ben Wang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Selective Laser Melting ◽  
Lattice Structure ◽  
High Strength ◽  
Ti6al4v Alloy ◽  
Laser Melting ◽  
Multi Scale ◽  
Tensile Performance

The tensile performance of Ti6Al4V alloy lattice structure was investigated.

Phase-Field Simulation of Dendrite Growth of Magnesium Alloy under Non-Isothermal Solidification

2013 ◽  
Vol 848 ◽  
pp. 231-235 ◽  
Author(s):  
Long Zhi Zhao ◽  
Xin Yan Jiang ◽  
Ming Juan Zhao ◽  
Jian Zhang
Keyword(s):  
Magnesium Alloy ◽  
Thermal Diffusion ◽  
Diffusion Layer ◽  
Phase Field ◽  
Primary Dendrite ◽  
Concentration Field ◽  
Dendrite Growth ◽  
Dendritic Morphology ◽  
Anisotropic Strength ◽  
Segregation Phenomenon

The phase-field model was built by coupling with the concentration field and temperature field,The dendrite growth process of Magnesium alloy was simulated under the different anisotropic strength and different undercooling.The results show that with the enlarge of anisotropic strength, dendritic morphology change from seaweed-like to snow-like, trunk grows along the optimal direction,and the secondary dendrite arm grow along the most optimize direction as well; With undercooling increasing, the more coarse primary dendrite arm, the more developed secondary dendrite arm, dendrites around the thermal diffusion layer becomes thinner,and dendrite tip’s thermal diffusion layer is thinner than the dendrite roots,but segregation phenomenon decreases slowly. When Δ=1.0, the grain will directly generate cellular dendrite and it does’t appear segregation phenomenon

scholarly journals The Morphology and Solute Segregation of Dendrite Growth in Ti-4.5% Al Alloy: A Phase-Field Study

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7257
Author(s):  
Yongmei Zhang ◽  
Xiaona Wang ◽  
Shuai Yang ◽  
Weipeng Chen ◽  
Hua Hou
Keyword(s):  
Steady State ◽  
Phase Field ◽  
Primary Dendrite ◽  
Turbine Blades ◽  
Solute Segregation ◽  
Dendrite Growth ◽  
Al Alloys ◽  
Al Alloy ◽  
Dendrite Morphology ◽  
Thermal Disturbance

Ti-Al alloys have excellent high-temperature performance and are often used in the manufacture of high-pressure compressors and low-pressure turbine blades for military aircraft engines. However, solute segregation is easy to occur in the solidification process of Ti-Al alloys, which will affect their properties. In this study, we used the quantitative phase-field model developed by Karma to study the equiaxed dendrite growth of Ti-4.5% Al alloy. The effects of supersaturation, undercooling and thermal disturbance on the dendrite morphology and solute segregation were studied. The results showed that the increase of supersaturation and undercooling will promote the growth of secondary dendrite arms and aggravate the solute segregation. When the undercooling is large, the solute in the root of the primary dendrite arms is seriously enriched, and when the supersaturation is large, the time for the dendrite tips to reach a steady-state will be shortened. The thermal disturbance mainly affects the morphology and distribution of the secondary dendrite arms but has almost no effect on the steady-state of the primary dendrite tips. This is helpful to understand the cause of solute segregation in Ti-Al alloy theoretically.

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