scholarly journals Research of structural entropy of sheet aluminium alloys depending on annealing temperature

2018 ◽  
Vol 224 ◽  
pp. 03005
Author(s):  
Ekaterina Nosova ◽  
Fedor Grechnikov ◽  
Natalia Lukonina
Keyword(s):  
Grain Size ◽  
Aluminium Alloys ◽  
Annealing Temperature ◽  
Cold Deformation ◽  
Grain Structure ◽  
Sheet Stamping ◽  
Structural Entropy ◽  
Size Uniformity

Sheet blanks’ structure uniformity determines their ability to sheet stamping. Level of entropy may represent the characteristic of structural uniformity. Structural entropy was received from strain curves recalculation for sheet blanks from aluminium alloys Al-2Mg and Al-6Mg are presented in the work. Stain curves were provided for blanks after cold deformation and annealing at temperatures 250, 350 И 450˚C. Estimation of grain size uniformity was made. Effect of annealing temperature on structural entropy and grain structure uniformity was found. It was shown that annealing temperature increasing leads to structural entropy decreasing. Ununiformity of grain size achieves the minimal values after annealing at temperature 350˚C for both alloys, and then ununiformity grows after annealing at temperature 450˚C.

Research of grain size homogeneity effect on sheet stamping ability characteristics of Al2Mg and Al6Mg alloys

2019 ◽  
pp. 47-54
Author(s):  
E. A. Nosova ◽  
A. A. Fadeeva ◽  
M. A. Starodubtseva
Keyword(s):  
Grain Size ◽  
Cold Work ◽  
Structural Features ◽  
Grain Structure ◽  
Recrystallization Annealing ◽  
Spring Back ◽  
Sheet Stamping ◽  
Bending Radius ◽  
Homogeneity Effect ◽  
Quality Of Products

The quality of products made of sheet aluminum alloys strongly depends on the technological features of the sheet stamping process, as well as on the structure of sheet semi-finished products. The grain size and grain structure uniformity are among the key structural features that influence stampability. A method is proposed and the homogeneity of the grain structure is evaluated. Stampability of Al2Mg and Al6Mg aluminium alloys was evaluated based on measurements of the spring back index, minimum bending radius, stamping ratio, and Martens strain index. Cold work (with a strain degree of 20 %) and subsequent recrystallization annealing at temperatures of 250, 350 and 450 °C for 1 h were used to obtain a grain structure of (26,8 Ѓ} 7,4)÷(126 Ѓ} 43) μm (Al6Mg alloy) and (120 Ѓ} 11)÷(264 Ѓ} 130) μm (Al2Mg alloy) in size. As a result of processing, the effect of the initial grain size was revealed: the coarser structure of the Al2Mg alloy led to a larger grain size after strain and annealing. It was found that an increase in the grain size in both alloys leads to an increase in the Martens index and a decrease in the stamping ratio, which indicates higher stampability of the alloys in the drawing operations of sheet stamping. In the Al2Mg alloy, an increase in the grain size leads to a decrease in the spring back index by 1,5–1,7 times, and an increase in the minimum bending radius. In the Al6Mg alloy, an increase in the grain size leads to an increase in the spring back index by 1,1–1,2 times, and a decrease in the minimum bending radius. The Al6Mg minimum bending radius remains higher compared to Al2Mg regardless of the grain size. Grain size inhomogeneity in the Al6Mg alloy causes an increase in the Martens index and minimum bending radius, and a decrease in the stamping ratio. In the Al2Mg alloy, grain size inhomogeneity causes an increase in the Martens index and minimum bending radius, and a decrease in the stamping ratio. For the spring back index, the increase in grain size inhomogeneity causes a high scatter of data. In the Al6Mg alloy, the low annealing temperature led to the preservation of the non-recrystallized structure, which influenced the decrease in stampability.

scholarly journals Experimental Investigation of Dry and Cryogenic Friction Stir Welding of AA7075 Aluminium Alloy

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
A. Praveen Raj Navukkarasan ◽  
K. Shanmuga Sundaram ◽  
C. Chandrasekhara Sastry ◽  
M. A. Muthu Manickam
Keyword(s):  
Grain Size ◽  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Dry Friction ◽  
Weld Zone ◽  
Grain Structure ◽  
Temperature Differential ◽  
Friction Stir ◽  
Aa 7075

An attempt has been made to investigate dry and cryogenic friction stir welding of AA 7075 aluminium alloy, which is predominantly availed in aerospace and defence component industries. These industries avail friction stir welding for joining two nonferrous materials, and minimal deviations and maximum strength are the preliminary and long time goal. A cryogenic friction stir welding setup was developed to conduct the joining of two aluminium alloy pipes. An increase of 0.76–42.93% and 3.79–31.24% in microhardness and tensile strength, respectively, is ascertained in cryogenic friction stir welding in correlation to dry friction stir welding of aluminium alloys. TOPSIS evaluation for the experimental run indicated tool profile stepped type, pipe rotation speed of 1000 rpm, welding speed of 50 mm/min, and axial force of 8 kN as close to unity ideal solution for dry and cryogenic friction stir welding of AA 7075 aluminium alloys. The friction stir-welded component under the cryogenic environment showcased drop in temperature, curtailed surface roughness, and fine grain structure owing to reduction in temperature differential occurring at the weld zone. A curtailment of 50.84% is ascertained in the roughness value for cryogenic friction stir welding in correlation to dry friction stir welding of AA 7075 alloy. A decrement of 21.68% is observed in the grain size in the cryogenic condition with correlation to the dry FSW process, indicating a drop in the coarse structure. With the curtailment of grain size and drop in temperature differential, compressive residual factor and corrosion resistance attenuated by 40.14% and 67.17% in the cryogenic FSW process in correlation to the dry FSW process, respectively.

scholarly journals Influence of hard cold working on microstructure and properties of annealing copper tubes

2002 ◽  
Vol 38 (3-4) ◽  
pp. 163-170 ◽  
Author(s):  
S. Ivanov ◽  
Desimir Markovic
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Mechanical Characteristics ◽  
Annealing Temperature ◽  
Cold Deformation ◽  
Deformation Degree ◽  
Chemical Content ◽  
Lower Annealing Temperature ◽  
Strength And Plasticity ◽  
Strength And Plasticity Characteristics

This work gives results of influence of temperature and deformation degree on changes in the metal grain growth of drawn copper tubes, because this mutual dependence was observed. Copper tubes samples, chemical content of 99,97 % Cu and 0,024 % P, were exposed to recrystallized annealing after drawing. The annealing was carried out at temperatures of 573, 623, 673, 723, 773, 823 and 873 K, for 60 minutes, in laboratory conditions. Investigation results show that after drawing with high cold deformation degree (96 - 99 %), the annealing leads to the changes in the continuous grain growth with increased temperature. The smaller grain size appears at 823 K in comparison with the lower annealing temperature. Annealing has influence on mechanical characteristics of tested samples and during drawing of copper tubes these characteristics are adequately changed: with regard to the annealing at the 773 K, the characteristics of strength and plasticity increase as a result of decreased grain size. The increase of annealing temperature to 873 K leads to the increased grain size and decreased values of strength and plasticity characteristics.

Development of Grain Structure and Texture during Annealing in Asymmetrically Rolled AA5754

2004 ◽  
Vol 467-470 ◽  
pp. 381-386 ◽  
Author(s):  
Hai Ou Jin ◽  
David J. Lloyd
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Annealing Temperature ◽  
Rolling Texture ◽  
Deformation Texture ◽  
Grain Structure ◽  
Asymmetric Rolling ◽  
Fine Grain ◽  
Continuous Recrystallization ◽  
Cold Rolling Texture

AA5754 sheet has been processed by asymmetric rolling and the development of grain structure and texture in subsequent annealing studied at 240-500°C. It has been found that asymmetric rolling facilitates the formation of ultra-fine grain structure (1-2µm grain size) by shear strain promoted continuous recrystallization, which is a process of extended recovery and subgrain/grain growth. The ultra-fine grain structure is not thermally stable, and when the annealing temperature or time increases, the grain size eventually grows to its Zener limit. The deformation texture is similar to the typical f.c.c. cold rolling texture but rotated about the transverse direction. Along with the formation of an ultra-fine grain structure and subsequent grain growth, the deformation texture is retained.

Mathematic Model of Recrystallization of Cu-20Ni-5Sn Alloy

2011 ◽  
Vol 239-242 ◽  
pp. 2252-2256
Author(s):  
Rui Qing Liu ◽  
Li Jun Peng ◽  
Jian Sheng Yang
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Annealing Temperature ◽  
Research Result ◽  
Cold Deformation ◽  
Mathematic Model ◽  
Kinetic Mechanism ◽  
Recrystallization Temperature ◽  
Total Deformation ◽  
Average Grain Size

Research the kinetic mechanism of grain growth of recrystallization of Cu-20Ni-5Sn alloy. The research result shows that the recrystallization temperature declines with the increase of cold-deformation. The recrystallization temperature is at about 500°C ~650°C respectively for 50% and 60% total cold deformation, and is about 470°C ~620°C respectively for 70% and 85% total deformation. The grains grow up with the increase of annealing temperature and holding time. The mathematic model of average grain size can be described as that Cu-20Ni-5Sn alloy annealed at 620°C ~680°C holding 2~10hours.

scholarly journals FRACTAL MODEL OF ESTIMATING QUALITY OF COLD WORKED FUEL CLADDING TUBES

2021 ◽  
pp. 57-63
Author(s):  
V.S. Vakhrusheva ◽  
V.M. Volchuk ◽  
N.V. Hruzin ◽  
I.A. Tiutieriev
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Grain Boundary ◽  
Cold Deformation ◽  
Fractal Dimensions ◽  
Grain Structure ◽  
Iteration Step ◽  
Cold Plastic Deformation ◽  
Fuel Cladding ◽  
Average Grain Size

A possibility was considered concerning estimation of grain anisomery in the structure of fuel cladding tubes of corrosion-resistant 026Cr16Ni15Mo3Nb steel of austenitic class rolled according to two flow charts: regular and intensive technologies using fractal formalism. Role of grain boundary hardening during cold plastic deformation was analyzed by studying the effect of the fractal dimension of grains D and their boundaries Dg on 0.2, w, and 5. The best correlation among those that were considered was observed between relative elongation and fractal dimensions of the grain structure (R2 = 0.90). The smallest correlation was observed with the yield stress (R2 = 0.64). It is because of variation of plastic flow processes towards a decrease in the degree of hardening in the material rolled according to the intensive technology. Cold deformation results in refining of the average grain size from 15.50 to 15.42 µm. In this case, extent of the grain boundary length L increased by 17.62% at an iteration step  commensurate with the average grain size which is indicated by a change in the fractal dimension according to L ~ δ1-D. Degree of the grain structure inhomogeneity was estimated using ratios of self-similarity of regions of fractal dimensions of the structure. The obtained results on the level of mechanical properties of fuel cladding tubes made of austenitic steel indicate advantage of the intensive technology over regular one that was confirmed by results of fractal modeling.

Grain Refinement and Strengthening of Aluminum Alloys: Cold Severe Plastic Deformation Model

2019 ◽  
Author(s):  
Xiao Guang Qiao ◽  
Nong Gao ◽  
Marco Starink
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Grain Refinement ◽  
Aluminium Alloys ◽  
Cold Deformation ◽  
Al Alloys ◽  
Deformation Model ◽  
Angular Pressing ◽  
Dislocation Movement ◽  
Very High

This paper presents a model which quantitatively predicts grain refinement and strength/hardness of Al alloys after very high levels of cold deformation through processes including cold rolling, equal channel angular pressing (ECAP), multiple forging (MF), accumulative rolling bonding (ARB) and embossing. The model deals with materials in which plastic deformation is exclusively due to dislocation movement, which is in good approximation the case for aluminium alloys. In the early stages of deformation, the generated dislocations are stored in grains and contribute to overall strength. With increase in strain, excess dislocations form and/or move to new cell walls/grain boundaries and grains are refined. We examine this model using both our own data as well as the data in the literature. It is shown that grain size and strength/hardness are predicted to a good accuracy.

Recrystallisation Behaviour of Cu-20Ni-5Sn Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1352-1356
Author(s):  
Rui Qing Liu ◽  
Li Jun Peng ◽  
Jian Sheng Yang
Keyword(s):  
Grain Size ◽  
Annealing Temperature ◽  
Research Result ◽  
Cold Deformation ◽  
Kinetic Mechanism ◽  
Holding Time ◽  
Recrystallization Temperature ◽  
Total Deformation ◽  
Hardness Tester ◽  
Average Grain Size

Investigate effects of annealing temperature and holding time on the recrystallization temperature, hardness, microstructure and average grain size of Cu-20Ni-5Sn alloy by hardness tester, microscope and XRD. Research the kinetic mechanism of grain growth of recrystallization of Cu-20Ni-5Sn alloy. The research result shows that the recrystallization temperature declines with the increase of cold-deformation. The recrystallization temperature is at about 500°C ~650°C respectively for 50% and 60% total cold deformation, and is about 470°C ~620°C respectively for 70% and 85% total deformation. The grains grow up with the increase of annealing temperature and holding time.

Structural and Electrical Characterization of Shaped Beam Laser Recrystallized Polysilicon on Amorphous Substrates

1981 ◽  
Vol 4 ◽  
Author(s):  
T. J. Stultz ◽  
J. F. Gibbons
Keyword(s):  
Grain Size ◽  
Electrical Characterization ◽  
Grain Structure ◽  
Electrical Characteristics ◽  
Shaped Beam ◽  
Beam Laser ◽  
Cw Laser ◽  
Amorphous Substrates ◽  
Circular Beam

ABSTRACTStructural and electrical characterization of laser recrystallized LPCVD silicon films on amorphous substrates using a shaped cw laser beam have been performed. In comparing the results to data obtained using a circular beam, it was found that a significant increase in grain size can be achieved and that the surface morphology of the shaped beam recrystallized material was much smoother. It was also found that whereas circular beam recrystallized material has a random grain structure, shaped beam material is highly oriented with a <100> texture. Finally the electrical characteristics of the recrystallized film were very good when measured in directions parallel to the grain boundaries.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

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