Twin Roll Research Articles

Effects of twin-roll casting process parameters on the microstructure and sheet metal forming behavior of 7050 aluminum alloy

In the present study, strips of 7050 aluminum alloys were cast using twin roll casting technology (TRC) where roll casting speed, roll gap, cooling water flow rate and initial cooling water temperature were varied. The optimized process parameters and their effects on TRC of 7050 aluminum alloys strips were investigated. The optimized process parameters and properties were obtained to be roll gap of 1.8mm, roll casting speed of 11.4m/min (12r/min), cooling water flow rate of 11.1m3/h and initial cooling water temperature of 20.8°C. The macro morphology, microstructure, hardness and yield stress of the strips were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and Vickers hardness. The homogeneous microstructures and improved mechanical properties were obtained by increasing the roll casting speed and roll gap thickness.

Development of Cube Recrystallization Texture in Strip Cast AA3004 Aluminium Alloy

AA3004 aluminium alloy is most widely used in the beverage industry due to its excellent deep drawing properties and corrosion resistance. During deep drawing of the AA3004 sheets, the ‘earing phenomenon’ has to be minimized for economic advantage. In AA3004 and modified AA3004 alloys (like AA3104), this can be achieved by tailoring the crystallographic texture of the fully recrystallized sheet. Conventionally, AA3004 sheets are produced through direct chill (DC) casting route. In the present study, a twin roll cast AA3004 sheet is used for further processing (cold rolling and annealing). The texture comprised mainly of Cu ({112} 〈111〉), Brass ({110} 〈112〉) and S ({123} 〈634〉) orientations in the as-cast as well as cold rolled condition (Cu, Brass and S components being stronger in the cold rolled condition as compared to as-cast material). After complete recrystallization of 90 % cold rolled sheet, cube texture are deviated from ideal cube ({100} 〈001〉) (5°–10°) along with formation of Goss ({110} 〈001〉) and P{011} 〈122〉 components. This was in contrast to the DC casting route, where strong cube recrystallization texture is obtained.

Microstructure and Mechanical Properties of Severely Deformed Mg-4.5Al-1.0Zn Alloy Processed by Asymmetric Rolling on Ingot and Twin Roll Cast Strip

The twin roll cast Mg-4.5Al-1.0Zn alloy sheets, processed by asymmetric rolling and subsequent annealing were investigated. The asymmetric rolling on Mg-4.5Al-1.0Zn ingot was also studied for comparison in terms of microstructure, texture and mechanical properties of the sheets. The results can be summarized as follows. The rolled sheets show intensively deformed band structures and fine grains due to dynamic recrystallization. After annealing at 375 °C for 1 hr, both the twin roll casted and ingot processed sheets show the fine equiaxed grains with around 9 μm in mean diameter. The twin roll casted magnesium alloy sheet shows superior tensile strength and low elongation compared to the ingot cast one. The results of this work suggest that asymmetric rolling can improve the formability of magnesium alloy and the technique could be extended to enhance the sheet qualities of different alloys in jewelry industry.

Study of the Structural Properties and Segregation of Alloying Elements in Strips from the TRC Line

Twin roll casting (TRC) technology is becoming increasingly popular because of the opportunity to receive aluminum strips which may serve as input for direct cold rolling processes. Furthermore, these strips have a favourable combination of mechanical and electric properties as well as dimensional tolerances. TRC line strips show segregation of alloying elements and structure providing a combination of casting structure and wrought alloy. As part of this study, the structure of the strips from the TRC line has been analyzed as well as the segregation of the alloying elements.

Influence of mechanical factors on solidification structure of thin strips of Fe–6.5wt-%Si alloy by twin roll casting process

Strips (1.6 mm thick) of Fe–6.5wt-%Si alloy were prepared by twin roll casting. The microstructure was found to be mainly columnar and equiaxed grains. The plastic deformation of the strip is inhomogeneous in the thickness direction. The most serious deformation is located at a certain depth from the strip surface. The influence of mechanical factors on the solidification structure of the strip is discussed. As the two solidifying shells contact with each other at the end of solidification, the columnar growth fronts break into fragments, which finally grow into equiaxed grains. At the hot rolling stage, the inhomogeneous deformation of the strip is attributed to the fact that the ductility of the alloy is sensitive to temperature. There is a large temperature gradient in the thickness direction, which can be up to 510°C mm− 1.

双ロールキャスティング中のアルミニウム合金の凝固におよぼすロール材質の影響

双ロールキャスティング中のアルミニウム合金の凝固におよぼすロール材質の影響

縦型タンデム双ロールキャスターによるAl合金クラッド材の作製

縦型タンデム双ロールキャスターによるAl合金クラッド材の作製

高アルミニウム含有Mg合金双ロールキャスト材の熱間鍛造材への応用

高アルミニウム含有Mg合金双ロールキャスト材の熱間鍛造材への応用

異径双ロールキャスターによるすべり軸受材料板の鋳造に関する研究

異径双ロールキャスターによるすべり軸受材料板の鋳造に関する研究

スクレイパーを装着した双ロールキャスターによるクラッド材の作製

スクレイパーを装着した双ロールキャスターによるクラッド材の作製

双ロールキャスターによる400mm幅クラッド材の作製

双ロールキャスターによる400mm幅クラッド材の作製

Fabrication Process of Al-SiCp Strip by Vertical Type High Speed Twin Roll Caster

Fabrication Process of Al-SiC_p Strip by Vertical Type High Speed Twin Roll Caster

P043 半凝固温度範囲が広いAl合金の双ロールキャスティング(メカボケーション学生研究発表セッション)

P043 半凝固温度範囲が広いAl合金の双ロールキャスティング(メカボケーション学生研究発表セッション)

Casting of Clad Strip by a Vertical Type Twin Roll Caster

A sound three-layer clad strip of 4045, 3003, and 4045 was cast by a vertical type tandem twin roll caster. However, a sound three-layer clad strip of 5182, 3003, and 5182 could not be cast. The 5182 overlay strip did not bond to the 3003 base strip. The latent heat of Si and Mg are 1787 kJ/kg and 230 kJ/kg, respectively. The latent heat affected the rise in temperature of the base strip. The 3003 was not heated up to a temperature suitable for bonding with the 5182 overlay strip. A sound two-layer clad strip of 3003 and 5182 could be cast by a twin roll caster equipped with a scraper. The temperature of the 3003 was near the solidus line, and sound bonding occurred.

Effect of microstructure on hot tensile deformation behavior of 7075 alloy sheet fabricated by twin roll casting

7075 aluminum alloy sheet with a thickness of 1mm was successfully fabricated by twin roll casting and subsequent rolling process. The hot tensile deformation behavior of 7075 alloy was evaluated and large elongation over 200% was obtained at 450°C under the high strain rate of 1×10−1s−1. In order to clarify the reason for the large elongation obtained at high strain rate, the effects of microstructure on hot tensile deformation behavior were investigated. The results show that high solidification rate during TRC casting process induced small particles (~1μm) in homogeneous distribution. The relatively high fraction of particles over 1μm in size attributed the homogeneous recrystallized microstructure with fine grains induced by particle simulated nucleation (PSN). This fully recrystallized fine-grained microstructure of TRC alloy sheet contributed to high ductility and formability of 7075 alloy sheet under high strain rate.

High Temperature Deformation of Twin-Roll Cast Al-Mn-Based Alloys after Equal Channel Angular Pressing.

Twin roll cast Al-Mn- and Al-Mn-Zr-based alloys were subjected to four passes of equal channel angular pressing. The resulting grain size of 400 nm contributes to a significant strengthening at room temperature. This microstructure is not fully stable at elevated temperatures and recrystallization and vast grain growth occur at temperatures between 350 and 450 °C. The onset of these microstructure changes depends on chemical and phase composition. Better stability is observed in the Al-Mn-Zr-based alloy. High temperature tensile tests reveal that equal channel angular pressing results in a softening of all studied materials at high temperatures. This can be explained by an active role of grain boundaries in the deformation process. The maximum values of ductility and strain rate sensitivity parameter m found in the Al-Mn-Zr-based alloy are below the bottom limit of superplasticity (155%, m = 0.25). However, some features typical for superplastic behavior were observed—the strain rate dependence of the parameter m, the strengthening with increasing grain size, and the fracture by diffuse necking. Grain boundary sliding is believed to contribute partially to the overall strain in specimens where the grain size remained in the microcrystalline range.

Inverse and centreline segregation formation in twin roll cast AZ31 magnesium alloy

Two microstructure defects formed in the twin roll cast AZ31 strips were investigated: inverse and centreline segregations. A two-dimensional finite element thermal–fluid–stress model was employed to study the thermomechanical response of the AZ31 strip during twin roll casting process. The results showed that the key parameter for centreline segregation is the mushy zone thickness at centreline. For inverse segregation, the interaction between the yy peak stress at the centreline in the mushy zone and the solidified shell on the roll surface is the determinant parameter. The modelling results suggested increasing the setback distance decreases the risk of both defects. Moreover, scaling up the caster reduces the propensity to inverse segregation but appears to have a minor effect for centreline segregation formation.

Fuzzy Controller Optimized by Genetic Algorithm for the Molten Metal Level in the Twin Roll Strip Casting Process

In the twin roll strip casting process, the control for the molten metal level is difficult owing to non-linear and time-varying of the control parameters. In the paper, on the basis of the geometry shape of the molten metal pool and the continuity of metal, the level mathematic model is built. Then a fuzzy control strategy is adopted to control the level. Moreover GA(Genetic algorithm) is used to obtain better fuzzy parameters. Simulations show the fuzzy controller optimized by GA greatly improves the control performance.

Study on the Stiffness Compensation Control Method in Twin Roll Strip Casting Process

In this paper, the stiffness compensation is used in the roll-gap controller to improve the reliability of the control system. Simulation research indicates that this method can enhance the control quality than traditional control strategy.

The impact of melt conditioning on microstructure, texture and ductility of twin roll cast aluminium alloy strips

Twin roll casting (TRC) is recognised as an effective processing route for producing low cost Al sheet. However, the quality of the Al alloys sheets produced by the TRC process is limited by the formation of centre-line segregation which prevents its application in a wide range of engineering sectors. To improve the quality of the TRC strips, a new technology, melt conditioning twin roll casting (MC-TRC) has been developed from the industrial point of view. Enhanced nucleation by melt conditioning favours the advance of an equiaxed solidification front which results in reduced sump depth and a refined, uniform, defect free microstructure. The results obtained show that the differences in microstructure and in the crystallographic texture have a significant impact on ductility (22% improvement) of the MC-TRC sheets compared to TRC sheets.