Influence of Cooling Rate on Primary Particle and Solute Distribution in High-Speed Twin-Roll Cast Al-Mn Based Alloy Strip

Sasisekharan, Ram; Harada, Yoshio; Kumai, Shinji

doi:10.2320/matertrans.f-m2017843

Cited by 17 publications

(7 citation statements)

References 23 publications

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“…This result showed good agreement with the directly measured cooling rates by using the thermocouples in the previous work. 5) 3.2 Solidification structure of 3003 aluminum alloy strip Figure 3 shows micrographs of the as-cast 3003 aluminum alloy strip. Columnar grains grew from both strip surfaces, and they were gradually replaced by the equiaxed grains along the thickness direction as shown in Fig.…”

Section: Effect Of Cooling Rates On Grain Size In As-cast 3003mentioning

confidence: 99%

“…The HSTRC is characterized by high cooling rates. 5) This feature is expected to lead to not only fine solidification structure including homogeneous distribution of fine secondary particles, but also enhanced solid solubility of solute atoms in the matrix. For dealing with increasing demand for thinner and stronger aluminum alloy sheets, the HSTRC is considered to be applicable to provide an ideal initial microstructure, which is a key to improve the final mechanical properties of AlMn based 3xxx alloy sheets.…”

Section: Introductionmentioning

confidence: 99%

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Solidification Structure and Secondary Particles in Vertical-Type High-Speed Twin-Roll Cast 3003 Aluminum Alloy Strip

Sasisekharan

Kumai

2019

Mater. Trans.

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The effect of cooling rate on microstructure of vertical-type high-speed twin-roll cast 3003 aluminum alloy strip was investigated. The solidification structure was characterized in terms of grain size and kinds, size, morphology and chemical composition of secondary particles. The 3003 aluminum alloy strip consisted of cell structure, dendritic structure, globular grains and eutectic structure along the strip thickness direction. From the relationship between the cooling rates and as-cast grain size, the cooling rate of high-speed twin-roll cast strip surface area was estimated as 3.1 © 10 3 K/s. Significant differences in the formation of secondary particles were found between direct chill (DC)-casting and the high-speed twin-roll casting as a result of the different cooling rates; Al 6 (Mn,Fe) and ¡-Al(Mn,Fe)Si phase were identified in the DC-cast sample, whereas only ¡-Al(Mn,Fe)Si was predominant in the high-speed twin-roll cast strip. The Al 6 (Mn,Fe) particles in DC-cast sample were script-like morphology with high aspect-ratio. In contrast, ¡-Al(Mn,Fe)Si particles in the high-speed twin-roll cast strip was spore-like morphology. Most ¡-Al(Mn,Fe)Si particles in the strip were considered to be formed as one of the eutectic components from the liquid droplets trapped in the inter-dendrite regions. In particular, Fe-rich ¡-Al(Mn,Fe)Si phase was formed at strip central area due to the increase in Fe segregation at the growth front. [

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Section: Effect Of Cooling Rates On Grain Size In As-cast 3003mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solidification Structure and Secondary Particles in Vertical-Type High-Speed Twin-Roll Cast 3003 Aluminum Alloy Strip

Sasisekharan

Kumai

2019

Mater. Trans.

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“…It was well known that dispersoids were the key strengthening phases for AA3xxx alloys at both room and elevated temperature. 3,5,12,21) But in the present study, the volume fraction of dispersoids decreased due to Cr addition (Table 5). However, the room and elevated temperature strength of materials increased as Cr content increased.…”

Section: Electronical Conductivity and Micro-hardnessmentioning

confidence: 44%

Effect of Cr Addition on Microstructure and Mechanical Properties at Elevated Temperature of Al–Mn–Mg–Si Alloys

Qin

Zhang

et al. 2020

Mater. Trans.

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Recently, the remarkable strengthening effect of ¡-Al(Mn, Fe) Si dispersoids at both ambient temperature and elevated temperature were found by several researches. In AA3xxx alloys, a large amount of dispersoids can form by applying suitable heat-treatment. In the present work, the influences of Cr addition on mechanical properties and microstructures of the AlMnMgSi alloys were investigated. The mechanical properties at ambient temperature were evaluated by micro-hardness and yield strength. Yield strength at 300°C and creep resistance at 300°C were used to evaluate materials' mechanical properties at elevated temperature. Moreover, the microstructures in as-cast and heat-treated conditions were quantitatively analyzed by optical and transmission electron microscopes. Results revealed that the addition of Cr increased area percentage of Mn-containing intermetallic particles. It also indicated that solubility of Mn element decreased due to Cr addition. Very little amount of Cr were detected in Mn-containing intermetallic particles and dispersoids. The distribution of dispersoids was not influenced by Cr addition. Number density and volume fraction of dispersoids decreased because of Cr. Electrical conductivity decreased significantly because of 0.30% Cr addition which indicated that a large amount of Cr were still in solid solution condition. Micro-hardness and yield strength at ambient temperature increased with the increasing content of Cr, and the Cr addition increased yield strength at elevated temperature as well. Moreover, creep resistance at 300°C improved dramatically with the increasing content of Cr.

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“…The surface region showed a relatively higher Mn concentration than that of the central region. The cooling rate was significantly higher at the surface than the central region [6]. This might be the main factor of the difference in Mn concentration between them.…”

Section: Mn Solubility Estimation By Electrical Conductivity (Ec) Valuesmentioning

confidence: 86%

“…In contrast, the vertical-type high-speed TRC (HSTRC) has a much higher casting speed compared to the horizontal-type. The strip can be produced at a very high cooling rate (over 10 3 C/s) [5,6]. The high cooling rate is considered to be effective not only for grain refinement but also for increasing the super-saturation of the alloying elements which leads to solid solution hardening and dispersion hardening.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of high-manganese-containing high-speed twin-roll cast Al-Mn-Si alloy strips and their cold-rolled sheets

et al. 2020

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Al-Mn based alloys with high-manganese content are expected to have improved mechanical properties due to solid solution hardening and/or dispersion hardening. However, the increase of Mn solubility of the alloy is difficult by using the conventional DC casting. In order to solve this problem, in the present study, we focused on the twin-roll casting method which is characterized by high cooling rates. Several kinds of high Mn-containing Al-Mn-Si alloy strips were fabricated by using a vertical-type high-speed twin-roll caster equipped with a pair of water-cooled copper rolls. Direct temperature measurement of the liquid melt during the casting was also performed. The alloy strips of various compositions containing up to 4 Mn and 2 Si (wt%) were successfully obtained. By observing the microstructure of the cross section of the strip, we found the characteristic solidified structure. The solidified structure consisted of three layers. Two solidified shells with a columnar dendrite structure grew from the roll surfaces toward the strip center. In the mid-thickness region, the band structure consisting of equiaxed dendrites and globular grains was observed between the solidified shells. Very fine primary particles were observed in the matrix near the strip surface, while, relatively coarse particles with blocky and needle-like shape were observed in the central band of the as-cast strip. The electric conductivity measurement was performed for the as-cast strips. Mn solubility in Al matrix was estimated from the obtained values. The estimated Mn solubility in the Al-2Mn-xSi strips was between 1.5 ~ 1.8wt% Mn. It was over 1.43wt%Mn for the Al-4Mn-xSi strips. We found that the Mn solubility of the as-cast strips was considerably high. The strips were cold-rolled to the sheets and then annealed at various conditions. They were subjected to the tensile tests, and the effects of solid solution hardening and dispersion hardening are discussed.

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Influence of Cooling Rate on Primary Particle and Solute Distribution in High-Speed Twin-Roll Cast Al-Mn Based Alloy Strip

Cited by 17 publications

References 23 publications

Solidification Structure and Secondary Particles in Vertical-Type High-Speed Twin-Roll Cast 3003 Aluminum Alloy Strip

Solidification Structure and Secondary Particles in Vertical-Type High-Speed Twin-Roll Cast 3003 Aluminum Alloy Strip

Effect of Cr Addition on Microstructure and Mechanical Properties at Elevated Temperature of Al–Mn–Mg–Si Alloys

Microstructure and mechanical properties of high-manganese-containing high-speed twin-roll cast Al-Mn-Si alloy strips and their cold-rolled sheets

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