scholarly journals Microstructure and Texture Evolution during Twin-Roll Casting and Annealing of a Mg–6.8Y2.5Zn–0.4Zr Alloy (WZ73)

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 513 ◽  
Author(s):  
Kristina Kittner ◽  
Madlen Ullmann ◽  
Falko Arndt ◽  
Rudolf Kawalla ◽  
Ulrich Prahl
Keyword(s):  
Grain Boundaries ◽  
High Temperatures ◽  
Texture Evolution ◽  
Cast State ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Average Grain Size ◽  
Different Temperatures ◽  
Twin Roll Cast ◽  
Twin Roll

In the present work, the microstructure and texture of a Mg–6.8Y–2.5Zn–0.4Zr sheet manufactured by twin-roll casting were investigated. The twin-roll cast state consisted of two apparent phases: the α-Mg matrix, which was made up of dobulites with an average grain size of approximately 50 µm and the LPSO (long-period stacking ordered) phase, which formed network-like precipitates along the grain boundaries. After twin-roll casting, annealing was carried out under conditions of different temperatures ranging from 450 °C to 525 °C and holding times between 2 h and 24 h. It was found that heat treatment led to the formation of a microstructure in which grains were apparent. Furthermore, it could be observed that high temperatures > 500 °C led to changes in the morphology of the LPSO structures. On one hand, the network-like structure dissolved while, on the other hand, both rodlike and blocky LPSO phases precipitated predominantly at the grain boundaries of the α-Mg matrix. This process was fostered by high temperatures and long holding times.

Twin-Roll Cast Al-Clad Magnesium Alloy

2009 ◽  
Vol 618-619 ◽  
pp. 467-470 ◽  
Author(s):  
A.K. Prasada Rao ◽  
K.H. Kim ◽  
J.H. Bae ◽  
Geun Tae Bae ◽  
Dong Hyuk Shin ◽  
...  
Keyword(s):  
Reaction Zone ◽  
Transverse Section ◽  
Intermetallic Phases ◽  
Alloy Sheet ◽  
Mg Alloy ◽  
Microstructural Investigation ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Twin Roll Cast ◽  
Twin Roll

An attempt has been made to clad Mg alloy with Al by twin-roll casting. This was done by inserting an Al sheet between the roll and the Mg alloy melt during twin-roll casting. Microstructural investigation across the transverse section of the as-cast Al-clad Mg alloy sheet reveals a very good interfacial bonding between Al and the base Mg alloy. Annealing of the Al-clad Mg alloy sheet results in the formation of layers of various intermetallic phases along the Mg/Al interface. Subsequent rolling of the as-annealed sheet significantly improves the formability of the reaction zone, as evidenced by the cracking of the base Mg alloy before the cracking of the reaction zone.

scholarly journals A Novel Approach to Improve the Microstructure and Mechanical Properties of Al–Mg–Si Aluminum Alloys during Twin-Roll Casting

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1713 ◽  
Author(s):  
Yong Li ◽  
Chen He ◽  
Jiadong Li ◽  
Zhaodong Wang ◽  
Di Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Crystallization Front ◽  
Alloying Elements ◽  
Cast Slab ◽  
Energy Dispersion Spectroscopy ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Twin Roll Cast ◽  
Twin Roll

The main purpose of this present study was to investigate the different processing conditions on the microstructure, segregation behavior of alloying elements, and mechanical properties of Al−Mg−Si alloy twin-roll cast slab prepared using a novel twin-roll casting technology. The simulation of temperature field, distribution of alloying elements, tensile properties, hardness, and conductivity were examined by a Leica optical microscope, scanning electron microscopy, energy dispersion spectroscopy, electron probe microanalysis, and tensile tests. The results indicated that when the traditional twin-roll casting method was used to produce aluminum alloy strip, there are obvious centerline segregation defects due to the deep crystallization front depth and symmetrical solidification characteristics. When the forced-cooling technology was applied in the twin-roll casting process, by virtue of the changing of crystallization front depth and crystallization front shape, the segregation defects are obviously suppressed. Suggesting that this method can significantly improve the uniformity of alloying elements in the thickness direction of the twin-roll cast slab, ultimately improve the mechanical properties of AA6022 aluminum alloy.

Influence Research of Al and Zn Addition for Twin Roll Casting Magnesium During Multi-Pass Hot Rolling

2020 ◽  
Vol 12 (5) ◽  
pp. 685-692 ◽  
Author(s):  
Jia Yao ◽  
Min Zha ◽  
Huiyuan Wang ◽  
Wei Lu
Keyword(s):  
Hot Rolling ◽  
Texture Evolution ◽  
Az31 Alloy ◽  
Thickness Reduction ◽  
Twin Roll Casting ◽  
Texture Intensity ◽  
Pinning Effect ◽  
Roll Casting ◽  
Zn Addition ◽  
Twin Roll

This study was aimed at revealing the influence of Al and Zn additions on microstructure, texture evolution and mechanical properties of twin roll casting Mg during multi-pass hot rolling. Firstly, both pure Mg and AZ31 sheets were rolled 9 passes with ∼80% thickness reduction. More effective grain refinement in AZ31 compared to pure Mg after hot rolling, which caused by the pinning effect from fine Mg17Al12 particles present in AZ31 alloy. Meanwhile a strong basal texture gradually formed with increasing thickness reduction in pure Mg. With Al and Zn adding, the texture intensity of AZ31 was much lower than pure Mg in each rolling-pass. The 5th AZ31 sample features a maximum intensity of ∼12.9, which is reduced by 50.6% as compared to the value of ∼26.1 for pure Mg. Compared to pure Mg, the Al and Zn solutes and weakened texture in AZ31 favor the strong work hardening, which promotes a simultaneous high ultimate tensile strength of ∼270 MPa and ductility of ∼22% in the 5th AZ31 sample. The results will be helpful for the TRCed Mg alloys with huge potential for industrial application.

Texture Evolution in Non-Oriented Silicon Steel Processed by Twin-Roll Casting

2012 ◽  
Vol 452-453 ◽  
pp. 7-11 ◽  
Author(s):  
Wei Pei ◽  
Yu Hui Sha ◽  
Fang Zhang ◽  
Liang Zuo
Keyword(s):  
Cold Rolling ◽  
Texture Evolution ◽  
Casting Process ◽  
Rolling Process ◽  
Silicon Steel ◽  
Recrystallization Annealing ◽  
Twin Roll Casting ◽  
Steel Sheets ◽  
Roll Casting ◽  
Twin Roll

In this paper, non-silicon steel sheets were produced by both twin-roll casting method and conventional process. Orientation characteristics and texture evolution of the sheets during casting, cold rolling and recrystallization annealing were investigated for comparison. It was found that the subsurface of twin-roll casting strips are characterized by weak {100} orientation while the central layer by random orientation. Twin-roll casting process can decrease α fiber (//RD) and increase γ fiber (//ND) during cold rolling process. Consequently, the η fiber (//RD) favorable for magnetic properties of non-silicon steels is enhanced and the detrimental {111} component is suppressed after annealing.

scholarly journals New Twin-Roll Cast Al-Li Based Alloys for High-Strength Applications

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 987
Author(s):  
Olexandr Grydin ◽  
Mykhailo Stolbchenko ◽  
Mirko Schaper ◽  
Sára Belejová ◽  
Rostislav Králík ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Light And Electron Microscopy ◽  
High Strength ◽  
Downstream Processing ◽  
Direct Chill ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Fine Grained Structure ◽  
Twin Roll Cast ◽  
Twin Roll

Al-Li based alloys are attractive materials for the aerospace industry. The twin-roll casting of such materials could provide properties not achievable by conventional direct-chill casting and downstream processing methods due to significantly higher solidification rates. An Al-Li-Cu-Mg-Zr alloy was twin-roll cast with the same alloy containing a small addition of Sc. The microstructure of as-cast materials and the influence of Sc on the behavior of the alloy at elevated temperatures were studied by means of light and electron microscopy and by resistivity measurements. A fine-grained structure was formed during twin-roll casting, but several surface and internal defects were found on the strips, which should be suppressed by a further adjustment of the casting conditions. The addition of Sc had a positive effect on grain size uniformity and microstructure stabilization at elevated temperatures, as shown by the precipitation of a fine dispersion of coherent Sc- and Zr-containing precipitates.

scholarly journals Hot Deformation Behavior and Microstructural Evolution of Twin-Roll-Casting Mg Alloy during High-Temperature Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Qingshan Yang ◽  
Jiahong Dai ◽  
Sensen Chai ◽  
Daliang Yu ◽  
Bin Jiang ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Microstructural Evolution ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Mg Alloy ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Average Grain Size ◽  
Twin Roll

The deformation behavior and microstructural evolution of twin-roll-casting AZ31 Mg alloy sheets were investigated via hot compression tests at 0°, 5°, and 10° from the normal direction. Compression strains of 5%, 15%, 25%, and 35% were employed at high temperatures of 450°C and 500°C. The flow stress as well as the difference in the flow stress associated with different sampling directions decreased when the temperature was increased. Furthermore, the volume fraction of dynamically recrystallized grains increased with increasing deformation, whereas the average grain size decreased. The DRX grain size and the volume fraction of dynamically recrystallized grains increased with increasing deformation temperature. During ultrahigh temperature compression, the effect of sampling direction on the compression microstructure is relatively small.

Solidification Microstructure and Mechanical Properties of Hot Rolled and Annealed Mg Sheet Produced through Twin Roll Casting Route

2011 ◽  
Vol 690 ◽  
pp. 331-334 ◽  
Author(s):  
M. Aljarrah ◽  
Elhachmi Essadiqi ◽  
D.H. Kang ◽  
In Ho Jung
Keyword(s):  
Mechanical Properties ◽  
Fuel Efficiency ◽  
Direct Chill ◽  
Alloy Sheet ◽  
Process Conditions ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Average Grain Size ◽  
Az31 Sheet ◽  
Twin Roll

The use of wrought magnesium for automobile structural components is an important component of the mass reduction strategy for automobiles to improve their fuel efficiency. Compared to Direct chill casting, Twin Roll Casting (TRC) allows major reduction of hot rolling steps in the production of Mg sheet due to the thin thickness of the as-cast strip. This TRC route can substantially reduce the time and cost to produce Mg alloy sheet product. In this work, AZ31 magnesium alloy was casted to 5 and 6 mm thick strips under different process conditions. Microstructure of these strips was analyzed using optical microscopy, SEM and EPMA. TRC strip was annealed under two different conditions: 2 hours at 330 and 1 hour at 400°C. It has been found that heat treatment at 400°C for 1 hour reduces centerline segregation significantly. TRC strips were rolled down to 2 mm and annealed at 450°C for 2 minutes. The average grain size was 4-6 µm and mechanical properties were comparable with commercial AZ31 sheet.

scholarly journals Comparison of Precipitates and Texture Evolution in Nb-Bearing Grain-Oriented Silicon Steel Produced by Conventional Processing and Novel Twin-Roll Casting

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1085
Author(s):  
Yang Wang ◽  
Yuanxiang Zhang ◽  
Feng Fang ◽  
Xiang Lu ◽  
Guo Yuan ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Secondary Recrystallization ◽  
Niobium Nitride ◽  
Silicon Steel ◽  
Electron Backscattered Diffraction ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Transmission Electron ◽  
New Type ◽  
Twin Roll

The Nb-bearing grain-oriented silicon steel sheets were produced by conventional route and novel twin-roll casting route, respectively. The microstructure, texture and precipitate evolution were comparatively investigated by using electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). The findings revealed that the precipitation behavior and the texture evolution were totally different between the two processing routes. In the conventional route, a great number of nanoscale niobium nitride particles (NbN), which acted as mainly grain growth inhibitors were precipitated during hot rolling, while in the twin-roll casting route, due to the rapid solidification, the precipitation of NbN were suppressed and a new type Nb-bearing precipitate enriched with sulfur element was observed in the as-cast strip. Besides, the primary recrystallized texture of conventional specimens was characterized by strong γ-fiber with a peak at {111} <110>, together with very few Goss components. While in the case of twin-roll casting specimens, the strongest primary recrystallized texture was {111} <112> texture and the area fraction of Goss component was much higher than that of conventional specimens. After final high temperature annealing, complete secondary recrystallization was obtained in twin-roll casting specimens and the magnetic induction of B8 was 0.1 T higher than that of conventional specimens.

Melt Conditioned Twin Roll Casting (MC-TRC) of Thin Mg-Alloy Strips for Direct Stamping of Mg Components

2013 ◽  
Vol 765 ◽  
pp. 170-174 ◽  
Author(s):  
Sanjeev Das ◽  
Shou Xun Ji ◽  
Omer El Fakir ◽  
Li Liang Wang ◽  
John P. Dear ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Hot Stamping ◽  
Az31 Alloy ◽  
Grain Structure ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Thin Walled ◽  
Twin Roll Cast ◽  
Twin Roll

In this paper we introduce a novel process for the production of thin-walled magnesium components by direct stamping of twin roll cast thin Mg strips. In this process, the melt conditioned twin roll casting (MC-TRC) process is used to produce thin Mg strips (thickness <2 mm) which have a fine equiaxed grain structure and little basal texture and, more importantly, are free from centreline segregation. Such thin Mg strips can be used for thin-walled component production by direct stamping without any rolling. A major advantage of this process is that it circumvents the low formability problem inherently associated with Mg based alloys. In this paper, AZ31 alloy is used to demonstrate this new process. For both TRC and MC-TRC strips, we will analyze the microstructures, assess the mechanical performance at elevated temperatures and conduct hot stamping in the as-cast condition without any prior rolling.

Microstructural Evolution of Al-Mn Based Alloy Fabricated by Vertical-Type High-Speed Twin-Roll Casting

2016 ◽  
Vol 877 ◽  
pp. 51-55 ◽  
Author(s):  
Ram Song ◽  
Yohei Harada ◽  
Shinji Muraishi ◽  
Shinji Kumai
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundaries ◽  
High Speed ◽  
Cooling System ◽  
Central Area ◽  
Eutectic Structure ◽  
Chemical Compositions ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Twin Roll

For decades, twin-roll casting has been applied for manufacturing aluminum alloy sheets. This conventional process contributes to make thin aluminum sheets from the molten metal directly. Recently, vertical-type high-speed twin-roll casting (HSTRC) has been developed with much higher casting speed rather than the horizontal-type. Some modifications such as feeding nozzle and water-cooling system of copper rolls contribute to increase cooling rates. This characteristic leads to many metallurgical advantages like grain refinement, super-saturation of alloying elements and fine distribution of secondary particles. The objective of this study is to investigate the constituent particles in HSTRC aluminum alloy. The commercial Al-Mn alloy strip was successfully fabricated by HSTRC. Clearly different microstructure was found in thickness direction. Many constituent particles observed along the grain boundaries/cell boundaries as well as inside of Al matrix on the surface area, while eutectic structure around globular grain boundaries was observed in mid-central area. The morphology as well as chemical compositions of the constituent particles were investigated.

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