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 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.

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.

Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction

2021 ◽  
Vol 13 (14) ◽  
pp. 7889
Author(s):  
Carlos Efrain Contreras Inga ◽  
Gabriel Walton ◽  
Elizabeth Holley
Keyword(s):  
Grain Size ◽  
Grain Shape ◽  
Grain Structure ◽  
Minor Effect ◽  
Unique Contribution ◽  
Structure Generation ◽  
Structure Representation ◽  
The Real ◽  
Study Results ◽  
Block Models

The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies.

Recrystallization and Grain Growth during Alloy 718 Processing

2007 ◽  
Vol 539-543 ◽  
pp. 3094-3099
Author(s):  
Nho Kwang Park ◽  
Jeoung Han Kim ◽  
Jong Taek Yeom
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heat Treatments ◽  
Grain Structure ◽  
Alloy 718 ◽  
Compression Tests ◽  
Δ Phase ◽  
Grain Boundary Characteristics ◽  
The Difference ◽  
Boundary Characteristics

In Alloy 718 ingot cogging process, dynamic and metadynamic recrystallizations, and static grain growth occur, and also the presence of δ phase plays a key role in controlling the grain size. In this study, the evolution of grain structure in VIM/VAR-processed Alloy 718 ingots during post-cogging heat treatments is dealt with. Compression tests were made on VIM/VAR-processed Alloy 718 ingot at temperatures between 900oC ~ 1150oC. Heat treatments were made on the compression-tested specimens, and the variation of grain size was evaluated. Constitutive equations for the grain growth are established to represent the evolution of microstructures. Special attention is paid to the evolution of grain structure under the condition of dynamic and metadynamic recrystallizations, and grain growth. The grain growth rate depends mainly on the presence of δ-phase below the δ-solvus temperature, and on the difference in the grain boundary characteristics above it.

The Influence of Section Thickness on Microstructure of Elektron 21 and QE22 Magnesium Alloys

2012 ◽  
Vol 191 ◽  
pp. 145-150 ◽  
Author(s):  
Michał Stopyra ◽  
Robert Jarosz ◽  
Andrzej Kiełbus
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Magnesium Alloys ◽  
Statistical Methods ◽  
Wall Thickness ◽  
Light Microscope ◽  
Volume Fraction ◽  
Grain Structure ◽  
Section Thickness ◽  
Gating System

The paper presents analysis of section thickness’ influence on microstructure of Elektron 21 and QE22 magnesium alloys in the form of a stepped casting test. Solid solution grain size and volume fraction of eutectic areas were measured using light microscope and sterological methods. The results showed the significant increase of grain size caused by wall thickness and its slight decrease connected with the distance beetwen analysed section and the gating system. This relationship was confirmed using statistical methods. QE22 alloy demonstrated finer grain structure than Elektron 21 alloy as well as lesser susceptibility of grain size to solidification conditions

Modeling of Dual-Phase Grain Structure in Ti-6Al-4V during Isothermal and Non-Isothermal Heat Treatment by Using Cellular Automata

2013 ◽  
Vol 753 ◽  
pp. 353-356
Author(s):  
Alfred Krumphals ◽  
Cecilia Poletti ◽  
Fernando Warchomicka ◽  
Martin Stockinger ◽  
Christof Sommitsch
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Cellular Automata ◽  
Isothermal Holding ◽  
Equilibrium Phase ◽  
Beta Phase ◽  
Grain Structure ◽  
Isothermal Heat Treatment ◽  
Dual Phase ◽  
Two Phase

In the titanium alloy Ti-6Al-4V the dual-phase grain structure, which forms during thermo-mechanical processing, is of high importance due to its effect on the mechanical properties. In general the most significant microstructural parameters are the amount of alpha and beta phase as well as their grain size. For this reason a new cellular automata method (CA) was developed to predict the evolving grain structure during isothermal and non-isothermal heat treatment. The probabilistic CA model is based on the diffusion controlled movement of grain and phase boundaries. During temperature changes an algorithm is adjusting alpha and beta phase fraction to maintain equilibrium phase values. Hence, the CA is capable to calculate grain coarsening as well as grain growth and shrinking in the two-phase area while heating and isothermal holding at forging temperature. The initial microstructure can be imported form virtual created microstructures, real micrographs and EBSD-images. The results are mean grain diameters, grain size distributions and virtually simulated microstructures which can be easily compared with real micrographs. The predicted microstructures are showing a good correlation to data in literature and experimental results.

Macro and Microstructural Effects of the Application of an Induced Axial Magnetic Field During the Deposition of Aluminum Weld Beads

2009 ◽  
Vol 1242 ◽  
Author(s):  
M. A. García ◽  
V. H. López M. ◽  
R. García H. ◽  
F. F. Curiel L. ◽  
R. R. Ambríz R.
Keyword(s):  
Magnetic Field ◽  
Grain Size ◽  
Magnetic Fields ◽  
Weld Metal ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Axial Magnetic Field ◽  
Grain Structure ◽  
Bead Geometry ◽  
External Power Source

ABSTRACTIn this work, aluminum weld beads were deposited on aluminum plates of commercial purity (12.7 mm thick), using an ER-5356 filler wire. The aim of the experiments was to assess the effects that yield the induction of an axial magnetic field (AMF) during the application of the weld beads using the direct current gas metal arc welding process (DC-GMAW). An external power source was use to induce magnetic fields between 0 to 28 mT. The effects of the magnetic fields were assessed in terms of the macrostructural features of the deposits, morphology of the grain structure, grain size and grain size distribution in the weld metal. Macrostructural characteristics of the weld beads revealed that increasing the intensity of the magnetic induction to produce a magnetic field above 14 mT, leads to a significant loss of feeding material and there is a tendency of the deposits to increase their width and reduce penetration. Perturbation of the weld pool induced by the application of the AMF noticeably modified the grain structure in the weld metal. In particular, for the intensities of 5 and 14 mT, columnar growth was essentially non-existent. Grain size distribution plots showed, generally speaking, that the use of magnetic fields is an efficient method to produce homogeneous grain structures within the weld metal. Finite element analysis was used to explain the weld bead geometry with the intensity of the magnetic field.

Improvement of Strength and Ductility by Combining Static Recrystallization and Unique Heat Treatment in Co-20Cr-15W-10Ni Alloy for Stent Application

2021 ◽  
Vol 1016 ◽  
pp. 1503-1509
Author(s):  
Kosuke Ueki ◽  
Soh Yanagihara ◽  
Kyosuke Ueda ◽  
Masaaki Nakai ◽  
Takayoshi Nakano ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Static Recrystallization ◽  
High Strength ◽  
Small Variation ◽  
Grain Structure ◽  
Fine Grain ◽  
High Temperature Short Time ◽  
Average Grain Size ◽  
Strength And Ductility

The Co-20Cr-15W-10Ni (CCWN, mass%) alloy has excellent corrosion resistance and strength-ductility balance and is applied in almost all balloon-expandable stent platforms. To further reduce the invasiveness of stent placement, it is necessary to reduce the diameter of the stent. That is, both high strength and high ductility should be achieved while maintaining a low yield stress. In our previous studies, it was discovered that low-temperature heat-treatment (LTHT) at 873 K improves the elongation of the CCWN alloy. In this study, we focused on the grain refinement by swaging and static recrystallization to improve the strength of the alloy. The as-swaged alloy was recrystallized at 1373–1473 K for 100–300 s, followed by LTHT. A fine grain structure with an average grain size of 3–17 μm was obtained by static recrystallization. The η-phase (M12X-M6X type precipitates, M: metallic elements, X: C and/or N) formed during the recrystallization at 1373–1448 K. The alloys recrystallized at 1448 and 1473 K had a homogeneous structure with a small variation in the grain size. On the other hand, the alloys recrystallized at 1373 and 1423 K had an inhomogeneous structure in which fine and coarse grains were mixed. Both the strength and ductility of the CCWN alloy were improved by combining high-temperature short-time recrystallization and LTHT.

Effect of Thermomechanical Processing on Grain Size, Texture and Mechanical Properties of Pure Magnesium

2020 ◽  
Vol 985 ◽  
pp. 97-108
Author(s):  
Mouhamadou Moustapha Sarr ◽  
Motohiro Yuasa ◽  
Hiroyuki Miyamoto
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Stress ◽  
Thermomechanical Processing ◽  
Pure Magnesium ◽  
Grain Structure ◽  
Misorientation Distribution ◽  
Processed Material ◽  
Texture Characterization

This study aims to investigate the effect of processing routes (A and Bc) and temperature on microstructure, texture and mechanical properties of pure magnesium was studied in this research. An extruded pure magnesium (~99,9 %) was subjected to severe plastic deformation (SPD) by ECAP. Deformation was conducted at 523K and 473K and two different processing routes (A and Bc) were used to control the texture. The microstructure and texture characterization of the pressed materials were carried out. It was found that the microstructure displayed a bimodal grain structure after two passes and then became homogeneous after four passes following both routes A and Bc. The misorientation distribution was examined and the results revealed that the fraction of high angle grain boundaries (HAGB) was higher at temperature 473K. The texture was randomized following route Bc whereas it became strengthened in route A after four passes. According to the Hall-Petch (HP) relationship, the yield stress of polycrystalline metals increases with a decrease in grain size. In this study, a positive slope k was achieved in the strengthened texture while a negative one was obtained in the softened texture. The ductility of ECAP processed material was considerably improved (from 23% to 38%) without sacrificing the yield stress by route Bc at 423K.

Sign in / Sign up

Export Citation Format

Share Document