scholarly journals Improving element uniformity and mechanical properties of Al-Mg-Si alloy fabricated by twin roll casting with superheat melt treatment

Author(s):  
Bowen Wei ◽  
Tao Jiang ◽  
Shiju Li ◽  
Youyun Zhang ◽  
Guangming Xu ◽  
...  

Abstract The effect of superheat melt treatment(SMT) on microstructure and properties of Al-Mg-Si alloy fabricated by twin roll casting(TRC) was analyzed using optical microscope, scanning electron microscopy, emission electron probe micro analyzer and transmission electron microscopy. SMT increased the subcooling degree of melt during TRC. The solidification microstructure with high dendrite density and small dendrite spacing was obtained. The second phase was evenly distributed between dendrites and the solute concentration gradient was decreased. Intergranular solute aggregation caused by Reynolds’ dilatancy in TRC slab was effectively suppressed. The homogeneous solute distribution of TRC slab with SMT can be realized by short-time homogenization heat treatment. The size of insoluble particles was greatly reduced. The complete decomposition of non-equilibrium eutectic phase increased the solute concentration in α-Al, which promoted the precipitation of precipitates during aging heat treatment. The tensile strength and yield strength of T6 slab were improved, while the uniform elongation are almost not decreased. The strength and uniform of slab in T4P state were both improved. The obtained results can help further shorten the production cycle of TRC slabs and improve mechanical properties.

2015 ◽  
Vol 620 ◽  
pp. 223-232 ◽  
Author(s):  
Sanjeev Das ◽  
N.S. Barekar ◽  
Omer El Fakir ◽  
Liliang Wang ◽  
A.K. Prasada Rao ◽  
...  

2013 ◽  
Vol 652-654 ◽  
pp. 2397-2403 ◽  
Author(s):  
Chun Fu Li ◽  
Hong Bin Wang ◽  
Fan Lei Meng ◽  
Hong Yang Zhao

In this study, 7050 aluminum alloy strip was produced using the twin-roll casting technique. Microstructures and properties of the cast-rolling 7050 aluminum alloy were investigated by means of optical microscope (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Vickers hardness test. The results indicate that microstructures of cast-rolling 7050 alloy strip are inhomogeneous on the cross section. From the edge to the center, the size of grain decreases gradually and becomes more homogeneous, showing a transition from dendrite grains to equiaxed grains. There are undissolved second phase particles in grains and at grain boundaries. And the dendrite grains and second phase particles can be reduced by solution treatment, and the hardness of the cast-rolling strip can be improved by aging treatment.


2021 ◽  
Vol 1016 ◽  
pp. 957-963
Author(s):  
Marie Moses ◽  
Madlen Ullmann ◽  
Rudolf Kawalla ◽  
Ulrich Prahl

Since 2018, the institute of metal forming has been studying the novel twin-roll casting (TRC) of magnesium wire at the pilot research plant set up specifically for this purpose. Light microscopic and scanning electronic investigations were carried out within this work and show the unique microstructure of twin-roll cast AZ31 magnesium alloy with grain sizes of about 10 μm ± 4 μm in centre and 39 μm ± 26 μm near the surface of the sample. By means of a short heat treatment (460 °C/15 min), segregations can be dissolved and grain size changes in centre to 19 μm ± 12 μm (increase) and near the surface to 12 μm ± 7 μm (decrease). Further, the mechanical properties of the twin-roll cast and heat-treated wire were analysed by tensile testing at room temperature. By heat treatment, the total elongation could be increased by a third whereas the strength decreases slightly. In heat-treated state, no preferred orientation is evident. In addition to the twin-roll cast and the heat-treated condition, the rolled state was analysed. For this purpose, the twin-roll cast wire was hot rolled using an oval-square calibration. After hot rolling, a dynamic recrystallization and grain refinement of the twin-roll cast wire could be achieved. It can be seen, that an increase in strength as well as in total elongation occur after wire rolling. Beside this, a rolling texture is evident.


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1713 ◽  
Author(s):  
Yong Li ◽  
Chen He ◽  
Jiadong Li ◽  
Zhaodong Wang ◽  
Di Wu ◽  
...  

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.


2018 ◽  
Vol 918 ◽  
pp. 48-53 ◽  
Author(s):  
Olexandr Grydin ◽  
Mykhailo Stolbchenko ◽  
Maria Bauer ◽  
Mirko Schaper

The industrial application of high-alloyed Al-Mg-Si alloys for the production of thin strips by means of twin-roll casting is limited due to the structural inhomogeneity and segregation formation. To reach the highest mechanical properties of the finished product, a direct influence on the strip formation conditions during the twin-roll casting can be applied. Analogous to the asymmetric rolling process, additional shear stresses were created in the strip forming zone by using different circumferential velocities and torques of the caster rolls. To provide the asymmetric process conditions, only one caster roll was left driven and the second one was left idling during the casting process. The microstructure and the mechanical properties of the strips in the as-cast state as well as after the homogenization and subsequent age-hardening were analyzed. A comparison of the test results showed a positive influence of the asymmetry conditions on the strips’ properties.


2017 ◽  
Vol 746 ◽  
pp. 184-191 ◽  
Author(s):  
Franz Berge ◽  
Marie Moses ◽  
Rudolf Kawalla ◽  
Madlen Ullmann

Magnesium sheets are used for wide-ranging applications in the automotive sector. In contrast to conventional magnesium processing routes for strips, twin-roll casting (TRC) and hot rolling is a cost-efficient production process for magnesium strips and sheets. As part of previous research strategies, the optimization of the thermomechanical treatment of magnesium alloys has resulted in excellent mechanical properties for the component design. However, the previously determined results at room temperature cannot be correlated with the warm forming behaviour during the component production. This is due to different deformation mechanisms, which are active at various temperatures. For TRC material, there is a lack of knowledge about the influence of heat-treatment and rolling on the final mechanical properties at hot working temperatures. This article depicts the investigations done on the influence of heat-treatment and hot rolling conditions on the mechanical properties of AZ31 strips at tensile deformation temperatures of 20 °C and 300 °C.


2017 ◽  
Vol 46 (3) ◽  
pp. 622-626 ◽  
Author(s):  
Yu Kun ◽  
Xiong Hanqing ◽  
Dai Yilong ◽  
Teng Fei ◽  
Fan Sufeng ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document