Grain Size Control of Wrought Aluminum Alloy for Rheology Forging by Electromagnetic Stirring and Its Mechanical Properties

Author(s):  
S.W. Oh ◽  
C.G. Kang ◽  
Byung Min Kim
Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5278
Author(s):  
Yi Guo ◽  
Yongfei Wang ◽  
Shengdun Zhao

Scroll compressors are popularly applied in air-conditioning systems. The conventional fabrication process causes gas and shrinkage porosity in the scroll. In this paper, the electromagnetic stirring (EMS)-based semisolid multicavity squeeze casting (SMSC) process is proposed for effectively manufacturing wrought aluminum alloy scrolls. Insulation temperature, squeeze pressure, and the treatment of the micromorphology and mechanical properties of the scroll were investigated experimentally. It was found that reducing the insulation temperature can decrease the grain size, increase the shape factor, and improve mechanical properties. The minimum grain size was found as 111 ± 3 μm at the insulation temperature of 595 °C. The maximum tensile strength, yield strength, and hardness were observed as 386 ± 8 MPa, 228 ± 5 MPa, and 117 ± 5 HV, respectively, at the squeeze pressure of 100 MPa. The tensile strength and hardness of the scroll could be improved, and the elongation was reduced by the T6 heat treatment. The optimal process parameters are recommended at an insulation temperature in the range of 595–600 °C and a squeeze pressure of 100 MPa. Under the optimal process parameters, scroll casting was completely filled, and there was no obvious shrinkage defect observed inside. Its microstructure is composed of fine and spherical grains.


2006 ◽  
Vol 116-117 ◽  
pp. 783-786 ◽  
Author(s):  
S.W. Oh ◽  
C.G. Kang ◽  
Byung Min Kim

This paper focuses on fabricated slurry by electromagnetic stirring (EMS) with A6061 and A7075 wrought aluminum alloys. For this EMS process, it is important to find the optimal electromagnetic stirring conditions such as pouring temperature, stirring current and stirring time. After electromagnetic stirring according to each condition, the billets fabricated by EMS were investigated, as was the microstructure and cooling temperature of molten alloy which was directly cooled from liquid state to the semi-solid state during EMS. In use of cooling time and temperature data, it is possible to determine the forming time and stirring time required, respectively.


2009 ◽  
Vol 487 (1-2) ◽  
pp. 163-172 ◽  
Author(s):  
V. Metan ◽  
K. Eigenfeld ◽  
D. Räbiger ◽  
M. Leonhardt ◽  
S. Eckert

Author(s):  
Ernest L. Hall ◽  
Lee E. Rumaner ◽  
Mark G. Benz

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.


Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 492
Author(s):  
Jan Foder ◽  
Jaka Burja ◽  
Grega Klančnik

Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at –40 °C using Charpy V-notch samples.


2021 ◽  
pp. 138770
Author(s):  
Linlin Guan ◽  
Leiming Yu ◽  
Lijuan Wu ◽  
Shuyu Zhang ◽  
Yuting Lin ◽  
...  

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