Papers by Keyword: AC4C Aluminum Alloy

Abstract: This study investigated on the cooling characteristics of AC4C aluminum alloy and AC7A aluminum alloy used as a casting material for manufacturing automobile tire mold by experiment. The metal mold device by gravity casting method was manufactured. AC4C casting material and AC7A casting material were heated in smelting furnace at about 650°C and 670°C, and then they injected into the metal mold device when the melting process was completely finished, respectively. When the melted casting material was completely injected into the metal mold device, the temperature inside the casting was measured by 9 measurement points. Also, when the temperature inside the casting was measured approximately 500°C during the cooling process, the casting is separated to metal mold device and carried out cooling at normal temperature. The separating time from metal mold device of AC4C casting material and AC7A casting material have been taken 25 minutes and 15 minutes, respectively. The final cooling time of AC4C casting material and AC7A casting material have been taken 400 minutes and 380 minutes, respectively. Accordingly, AC7A casting material is able to improve on productivity than AC4C casting material because production time was decreasing.

Abstract: The static and dynamic properties on the hoist hook of a vessel are necessary since they are affected by the damages of a static and dynamic load. Al-Si-Mg casting alloy (AC4C-T6) is widely used due to its good mechanical properties as well as the light weight and good casting with complex geometries. This study accomplished a static tension test and an impact test. Based on the test results and fracture surface analysis, we found that there are great differences between the fracture strain and yield stress in the different extracted regions of specimen. In tensile test, yield stress were 205 MPa at a low strain rate of 5 mm/min and 220 MPa at a high strain rate of 25mm/min. In Charpy impact test, impact properties of AC4C aluminum alloy were analyzed by impacting loading versus displacement and impacting energy versus displacement. Compared the fracture strains in different strain rates, maximum fracture strain of low strain rate was mainly 10 % higher than that of high strain rate. There were more than 20 % differences in the strain rate. The ductile and brittle behaviors were showed in low strain rate and high strain rate in static tensile test, respectively. The impact energy reached high when they were extracted from a plane region in the mold. But impact energy reached low when they were extracted from a curved and edge region. It is demonstrated that mechanical properties and impact energy of the samples where were extracted from a curved and edge region was lower than that of the samples where were extracted from a plane region.

Abstract: This study was investigated about that behavior of α phase during recrystallization process and the influence of the amount of strain on semi-solid structure of AC4C aluminum alloy which was processed by one way torsion working. AC4C aluminum alloy billets having a diameter of 35mm and a length of 400mm were torsioned by a single side torsion machine. The maximum strain (γmax) of the specimens in this experiment was 0.88. The specimens were etched for the microstructure observation by optical microscope. The casting material (γ＝0) and the torsion material (γ＝0.73) were remained dendrite structure from room temperature to 565°C. The casting materials had grain-shaped structure when they reached to 585°C which is an eutectic temperature in this alloy. However the torsion working material had it when they reached to 577°C from eutectic temperature on down. In semi-solid region, the structure of the torsion working material was finer than that of casting material and became a more grain-shaped structure. The casting material which was heated to the eutectic temperature was changed to dendrite structure again. However the torsion working material was remained grain-shaped structure.