Effect of Melt Intensive Homogenization on Solidification Microstructure of 7075 Aluminium Alloy by Twin-Screw Stirring

Intensive melt shearing achieved using a twin-screw machine was applied to the 7075 aluminum alloy melt to investigate its effects on grain refinement. Alloy melt without and with melt shearing was cast in the standard test procedure mould, and the effects of casting temperature, shearing time and shearing intensity on microstructures were analyzed. The results show that the intensive melt shearing exhibits superior grain refinement and remarkable structure homogeneity. Without shearing, the grain size increases significantly with the increase in pouring temperature, while with intensive melt shearing the grain size is finer at all the pouring temperatures tested with a reduced grain size dependence on the pouring temperature. With the shearing time or shearing intensity increasing, the grain size of the equiaxed primary α (Al) phase decreases on the sample microstructures, and the grain distributions trend to become more fine and non-dendritical.

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Dynamic Recrystallization Microstructure Grain Size Prediction of 7075 Aluminum Alloy Piston Prepared by Isothermal Extrusion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1042.81 ◽

2014 ◽

Vol 1042 ◽

pp. 81-86 ◽

Cited By ~ 1

Author(s):

Yue Wu ◽

Wen Lin Chen ◽

Yan Gao ◽

Rui Zhou

Keyword(s):

Grain Size ◽

Finite Element ◽

Aluminum Alloy ◽

Theoretical Calculation ◽

Grain Refinement ◽

Extrusion Process ◽

7075 Aluminum Alloy ◽

Lateral Extrusion ◽

Element Simulation ◽

Isothermal Extrusion

According to the structure features of the piston, the method of combining application of finite element simulation and theoretical analysis was explored to determine the extrusion process program and the extrusion process parameters. Theoretical calculation shows that a longitudinal extrusion and a lateral extrusion can form piston. The result comparing simulative prediction with theoretical calculation demonstrates that there is a good fit between the two and the theoretical calculation is right. The result of simulative prediction demonstrates that the grain size of piston after extrusion is about 17.8 μm and the refining rate reaches 55%. The grain size on both sides of the piston skirt and piston internal floor place is about 27 μm, so the refining effect is less obvious than other parts. However, the grain refinement in the piston pin holes is more obvious, the grain is refined to 13 μm and the refining rate is about 67.5%.The result comparing simulative prediction with the experimental analysis demonstrates that there is a good fit in grain refinement between the two.

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Effect of Annular Electromagnetic Stirring Process on Solidification Microstructure of 7075 Aluminium Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.652-654.2418 ◽

2013 ◽

Vol 652-654 ◽

pp. 2418-2426 ◽

Cited By ~ 2

Author(s):

Zhi Hua Gao ◽

Jun Xu ◽

Zhi Feng Zhang ◽

Meng Ou Tang

Keyword(s):

Aluminum Alloy ◽

Aluminium Alloy ◽

Grain Refinement ◽

Electromagnetic Stirring ◽

7075 Aluminum Alloy ◽

Pouring Temperature ◽

Conventional Casting ◽

Annular Gap ◽

Solidification Microstructures ◽

Gap Width

7075 aluminum alloy melt conditioned by annular electromagnetic stirring(A-EMS) was cast in the TP1 mould, and the effects of pouring temperature, stirring current, stirring frequency and annular gap width on microstructures were analyzed. The A-EMS process exhibits superior grain refinement and remarkable structure homogeneity compared with conventional casting(N-EMS) and conventional electromagnetic stirring casting(EMS). With the increasing of the pouring temperature, the microstructures of the sample conditioned by A-EMS are inclined to become coarse and non-uniform compared with which have the more serious inclination conditioned by N-EMS. With the stirring current or stirring frequency increasing, the rosette-like or dendritic primary α(Al) phase decreases significantly on the sample microstructures, and the non-dendritic primary α(Al) phase is finer and more spherical. Narrow annular gap is advantageous to obtain uniformly fine spherical solidification microstructures.

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Effect of In Situ TiB2 Particles on the Grain Size and Mechanical Properties of 7075 Aluminum Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1035.102 ◽

2021 ◽

Vol 1035 ◽

pp. 102-107

Author(s):

Shao Ming Ma ◽

Chuan Liu Wang ◽

Yun Lin Fan

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Aluminum Alloy ◽

High Strength ◽

Light Weight ◽

7075 Aluminum Alloy ◽

Directional Drilling ◽

High Strength Aluminum Alloy ◽

Drill Pipes

Light-weight and high-strength aluminum alloy drill pipes are potential and promising to replace traditional steel drill pipes. In this study, the grain size and mechanical properties of aluminum alloy drilling pipe materials reinforced by in-situ TiB2 particles were studied. The results showed when reinforced by in-situ TiB2 particles the grain size of aluminum alloy materials was refined from 155 m to 57 m and ultimate tensile strength was increased from 590 MPa to 720 MPa. Besides, the results also indicated that the friction coefficient was reduced from 0.99 to 0.50 and thus the abrasion resistance of 7075 aluminum alloy was enhanced by 34 %. This study provided theoretical basis for the application of light-weight and high-strength aluminum alloy drill pipes in directional drilling and ultra-deep wells.

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Synergistic Effect of La and TiB2 Particles on Grain Refinement in Aluminum Alloy

Materials ◽

10.3390/ma15020600 ◽

2022 ◽

Vol 15 (2) ◽

pp. 600

Author(s):

Lili Zhang ◽

Yan Song ◽

Linjie Yang ◽

Jiuzhou Zhao ◽

Jie He ◽

...

Keyword(s):

Grain Size ◽

Aluminum Alloy ◽

Synergistic Effect ◽

Grain Refinement ◽

Grain Refining ◽

Average Grain Size ◽

Calculation Results ◽

La Addition ◽

Tib2 Particles ◽

Addition Level

Synergistic effect of TiB2 (in form of Al-5Ti-1B) and La on grain refining results in Al-2Cu alloy was investigated. α-Al grains are significantly refined by Al-5Ti-1B. When trace La is added to the melt, further refinement is exhibited. Average grain size and nucleation undercooling of α-Al reduce first and then almost remain unchanged with La addition. Satisfactory grain refining result achieves when La addition level reaches 600 ppm. When more than 600 ppm La is added to the melt, La-rich particles form and the effect of solute La left in matrix on the microstructure almost no longer changes. Theoretical calculation results demonstrate that solute La segregates to Al melt/TiB2 particles interface along with Ti and Cu prior to α-Al nucleation and the synergistic effect of La and TiB2 particles on grain refinement mainly attributes to the enhancement in the potency of TiB2 particles to heterogeneously nucleate α-Al by trace La addition.

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Effect of two-dimensional ultrasonic rolling on grain size and micro-hardness of 7075 aluminum alloy

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-019-04640-y ◽

2019 ◽

Vol 106 (1-2) ◽

pp. 503-510

Author(s):

Jianxin Zheng ◽

Hongwei Liu ◽

Yuanchao Ren ◽

Lixin Zhu

Keyword(s):

Grain Size ◽

Aluminum Alloy ◽

Two Dimensional ◽

7075 Aluminum Alloy ◽

Micro Hardness

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Research on the Strength Improvement of 7A04 Aluminum Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.488-489.19 ◽

2012 ◽

Vol 488-489 ◽

pp. 19-21

Author(s):

Chao Jue Yi ◽

Peng Cheng Zhai ◽

Li Zhou Dong ◽

Qi Hao Fu

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Tensile Strength ◽

Aluminum Alloy ◽

Grain Refinement ◽

Cryogenic Treatment ◽

The Impact ◽

Strength Improvement

By using cryogenic treatment on 7A04 aluminum alloy tested with micrographic analysis and mechanical properties test, we studied the impact on mechanical properties of 7A04 aluminum alloy The results showed that the strength of 7A04 aluminum alloy could be highly increased and the grain size would be reduced in the process through being treated in 480°C/80min + aging in 120°C/4h + cryogenic treatment + aging at 120°C/16h.7A04 aluminum alloy are more fully recrystallized to grain refinement and the tensile strength of it can be increased to 720Mpa after the treatment.

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Grain Evolution Character of Discal Parts by Roll Forming

Materials Science Forum ◽

10.4028/www.scientific.net/msf.749.328 ◽

2013 ◽

Vol 749 ◽

pp. 328-336

Author(s):

Quan Lin Jin

Keyword(s):

Numerical Simulation ◽

Grain Size ◽

Titanium Alloy ◽

Aluminum Alloy ◽

Dynamic Recrystallization ◽

Strain Rate ◽

Grain Refinement ◽

Grain Growth ◽

Roll Forming ◽

Alloy 6061

A study on grain evolution character of discal parts roll forming was carried out by means of experiment and numerical simulation. The discal part material is aluminum alloy 6061 and titanium alloy TC4. The roll forming temperature is 480-500 and 930-1020 for aluminum alloy 6061 and titanium alloy TC4, respectively. A digital double-sided roll forming machine was used for roll forming experiment of discal parts. The high frequency induction heating was used for disk heating, where the deformation zone is in the state of constant temperature. A numerical simulation of roll forming of the 6061 aluminum alloy disk was carried out. The simulated results include macroscopic deformation and various grain size evolution variables. The dynamic recrystallization, the dynamic and static grain growth were considered in the numerical simulation. The experimental and simulated results showed that there may appear not only the grain refinement due to dynamic recrystallization but also dynamic and static grain growth. It is different that from discal parts integrally forging there are the largest deformation, the highest strain rate and the best recrystallization and grain refinement in the zones contacted with the roll tools. In the zones far from the rollers, the strain rate is very low and average grain size increases until once again contact to the rollers and start new grain refinement.

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Grain Refinement in Constrained Groove Pressing of 7050 Aluminum Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.2823 ◽

2011 ◽

Vol 189-193 ◽

pp. 2823-2826 ◽

Cited By ~ 1

Author(s):

Xiao Lei Dong ◽

Bing Yun ◽

Zhi Hao Ma

Keyword(s):

Experimental Data ◽

Grain Size ◽

Regression Analysis ◽

Aluminum Alloy ◽

Grain Refinement ◽

7050 Aluminum Alloy ◽

Simulation Results ◽

Refinement Effect

Constrained groove pressing is a simple and effective method of grain refinement. Using the experimental data obtained by regression analysis, this paper analyzes the simulation of the four pass constrained groove pressing deformation of 7050 aluminum alloy. The simulation results show that the grain size of the billet is refined significantly after four pass constrained groove pressing deformation and decreases from the original 90 μm to a minimum of 14.0 μm. With the increase of the number of deformation passes, refinement effect becomes weakened gradually, the grain size tends to stabilize and the organization is more uniform.

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Refinement of Primary Silicon Grains in Semi-Solid Al-25%Si Hypereutectic Aluminum Alloy Slurry

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.285.153 ◽

2019 ◽

Vol 285 ◽

pp. 153-160 ◽

Cited By ~ 1

Author(s):

Wei Min Mao ◽

Peng Yu Yan ◽

Z.K. Zheng

Keyword(s):

Grain Size ◽

Aluminum Alloy ◽

Research Work ◽

Good Method ◽

Primary Silicon ◽

Pouring Temperature ◽

Channel Bend ◽

Traditional Process ◽

Semi Solid ◽

Inner Channel

s: The semi-solid slurry of Al-25%Si hypereutectic aluminum alloy was prepared through a copper serpentine pouring channel, the effect of pouring temperature and numbers of channel bend on the slurry microstructure was investigated. The results show that the primary silicon grains in Al-25%Si hypereutectic alloy solidified at a traditional condition are very large and the average silicon grain size is about 65.3μm, however, when the liquid Al-25%Si alloy is poured through a copper serpentine pouring channel, the primary silicon grains are fined obviously. If the channel has three bends and the pouring temperature is 747°C,the average silicon grain size in the slurry is about 33.7μm. If the channel has four bends and the pouring temperature is 747°C, the average silicon grain size in the slurry is about 30.9μm. If the channel has seven bends and the pouring temperature is 747°C, the average silicon grain size in the slurry is about 28.6μm. The analysis shows that the chilling effect of the inner channel wall precipitates primary silicon nuclei, and so the primary silicon grains of Al-25%Si alloy are fined greatly. Meanwhile, the subsequent washing of the alloy melt also promotes the separation of primary silicon grains from the inner wall and the primary silicon grains are further fined. The above research work demonstrates eventually that the copper serpentine pouring channel process is a good method for fining the primary silicon grains in hypereutectic Al-25%Si alloy rather than using chemical fining agent phosphorus as in traditional process.

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